Research reported in this publication was supported by the National Institute on Deafness and Other Communication Disorders of the National Institutes of Health under award number R01DC014460. Video production and editing was carried out by Robert Ladd and Barbara Rochen Renner of the Health Sciences Library at The University of North Carolina at Chapel Hill, with support from a National Library of Medicine of the National Institutes of Health Administrative Supplement for Informationist Services in NIH-funded Research Projects under award number R01DC011038. Children were recruited through the Research Participant Registries of the IDDRC at The University of North Carolina at Chapel Hill (NIH-NICHD award number U54HD079124). We appreciate Emily Buss' comments on this procedure and a previous version of this article. The authors would also like to thank Steve Lockhart for programming support and members of the Human Auditory Development Laboratory for testing assistance: Jenna Browning, Lauren Charles, Nicole Corbin, Molly Drescher, Hannah Hodson McLean, Heather Porter and Dani Warmund. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

The Institutional Review Board at The University of North Carolina at Chapel Hill approved this research.
1. Personnel and Space Requirements
<ol>
	<li>Perform testing in a sound-isolating room. Configure the room with a table and chairs, as shown in Figure 1.</li>
</ol>
<img alt="Figure 2" src="/files/ftp_upload/54788/54788fig1.jpg" /> 
Figure 1: Test environment. The assistant and the listener are seated at a table inside the sound booth. The child&#39;s parent may elect to sit inside or outside the booth. The observer sits outside the booth, positioned in front of the window for good visibility of the assistant and the child. The computer screen and keyboard controlling the run-time computer are accessible to the observer, allowing him/her to initiate trials and enter responses. <a href="http://cloudfront.jove.com/files/ftp_upload/54788/54788fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<ol start="2">
	<li>Use two experimenters to test toddlers and preschoolers; an &#34;assistant&#34; who sits inside the booth with the child and an &#34;observer&#34; who is in the adjacent control room. 
	NOTE: The role of the assistant inside the booth is to: (1) train the child to perform a simple play-based motor response (e.g., stacking blocks) whenever the target signal is heard; (2) provide reinstruction whenever necessary; (3) socially engage the child throughout the testing session; (4) change the game the child is playing based on the child&#39;s level of interest; and (5)&#160;provide social reinforcement (e.g., clapping or cheering) following trials in which the child performs the targeted motor response. 
	NOTE: The role of the observer seated outside of the booth is to: (1) observe the child and assistant inside the booth through a window; (2) initiate test trials when the child is quiet and in a &#34;ready&#34; position; and (3) indicate whether the child heard the sound in the 1st or 2nd interval following each test trial by clicking on the corresponding response button in the computer software user interface. This decision is based solely on the child&#39;s response. 
	NOTE: The experience level of the experimenters will affect the yield rate and data obtained. In this experiment, all observers and assistants had at least two years of experience testing toddlers and preschoolers in the audiology clinic and/or research laboratory.</li>
	<li>Locate the computer and hardware in the control room. Position the computer monitor so the observer can view the monitor as well as the child and the assistant inside the booth.</li>
	<li>Equip the testing space with a two-way communication system between the observer and the assistant. 
	NOTE: This system allows the two testers to work together to ensure trials are initiated when the child is alert and oriented to the task.</li>
</ol>
2. Hardware and Software Configuration
<ol>
	<li>In this example, custom software controls a real-time processor, which routes the sound to an insert earphone. Alternatively, a soundcard system with precise control of stimulus timing can be used.</li>
	<li>Select a target signal. In this example, the signal is a 500 msec, 1,000 Hz warble tone.</li>
	<li>Present the stimuli through an earphone that is appropriately calibrated to ensure the sound levels presented to the listener are accurate and safe.</li>
	<li>Program the custom software to control the timing of the two observation intervals for each trial. 
	NOTE: In this example, each observation interval is 1,065 msec in duration, and intervals are separated by a 300 msec inter-stimulus interval. Thus, the total duration of each trial is 2,430 msec.</li>
	<li>Collect pilot data to help select appropriate durations for the signal, the observation intervals and inter-stimulus interval. Optimal durations may vary depending on the stimulus and the population and/or age of children being tested.</li>
	<li>Program the software to provide an audio and visual prompt to mark the two intervals. In this example, an audio prompt is a voice recording of a female talker saying &#34;one&#34; and &#34;two.&#34; Both the observer and the assistant hear the audio prompt. The visual prompt appears as a flashing black circle on the monitor screen. Only the observer sees the visual display. 
	NOTE: The observer uses these time-locked auditory and visual interval indicators, in conjunction with observations of the listener&#39;s behavior, to determine which interval contained the target signal.</li>
	<li>Program the software to indicate which interval contains the signal only after the observer has entered a response.</li>
	<li>Program the custom software to execute the three stages of the testing protocol. The purpose and main features of each stage are as follows:
	<ol>
		<li>In Stage 1, present the signal at a fixed and clearly audible level, always in interval 2. Select the training level intensity based on pilot data. After three trials in Stage 1, program the software to prompt the observer to either repeat Stage 1 or initiate Stage 2. 
		NOTE: The purpose of Stage 1, the operant conditioning stage, is to teach the listener to perform a play-based, motor response as soon as he/she hears the signal.</li>
		<li>In Stage 2, program the software to allow the signal to occur in either interval 1 or interval 2, with equal a priori probability. Present the signal at the same audible level used in Stage 1. Program Stage 2 to continue until the observer correctly judges the observation interval containing the signal on 4 out of 5 consecutive trials. 
		NOTE: The purpose of Stage 2, the verification stage, is to ensure the observer can reliably judge the interval containing the signal based solely on the child&#39;s behavior.</li>
		<li>Program Stage 3 to collect experimental data. In this example, the software is program to run an adaptive track procedure in Stage 3. The signal occurs in either interval 1 or interval 2, with equal a priori probability. 
		NOTE: The present example uses a 2-down, 1-up adaptive tracking procedure to estimate the signal level associated with 71% correct detection16. The track continues for 8 reversals, and threshold is based on the last 6 reversals.</li>
		<li>Program the software to also present probe trials in Stage 3. Responses on probe trials reflect consistency of responses to supra-threshold signals across the testing session. During a probe trial, present the signal at the same clearly audible level used in the two training stages (Stage 1 and Stage 2). Randomly present probe trials twice out of every 12 trials. Consider a track invalid if the average probe hit rate is &#60;80%.</li>
	</ol>
	</li>
	<li>For all three stages, program the software to require the observer to initiate a trial by clicking on a response box in the user interface.</li>
	<li>Program the user interface to allow the observer to click on a box to indicate which interval contained the signal. After the response is entered, provide feedback to the observer indicating the interval that contained the signal.</li>
	<li>Program the software to activate two mechanical toys with lights that are located in dark Plexiglas boxes in the testing room.
	<ol>
		<li>Use mechanical toys as reinforcements, in addition to an assistant providing social reinforcement in the test booth.</li>
		<li>Design the program to maintain a consistent delay between the signal and the activation of the toy, regardless of whether the signal occurs in interval 1 or 2. If the signal occurs in interval 1, the mechanical toy is activated immediately following the observer&#39;s response. If the signal occurs in interval 2, the mechanical toy activation is delayed by the interval duration plus the inter-stimulus interval (1,365 msec in this example).</li>
		<li>Activate the mechanical toy only if the observer correctly judges the interval that contained the signal.</li>
	</ol>
	</li>
</ol>
3. Data Collection
<ol>
	<li>Prepare the environment before the child arrives to the laboratory, as detailed in Figure 1.</li>
	<li>Select 4 to 6 games for the test session based on the child&#39;s age, motor control, and interests. Examples include placing pegs into a board, putting blocks into a bucket, completing a puzzle, and placing felt pieces onto a board to make a scene.</li>
	<li>Complete a listening check of the experimental stimuli and the observer-assistant communication system.</li>
	<li>As soon as the child and parent arrive at the laboratory, obtain informed consent for participation in the study.</li>
	<li>Instruct the child and parent to enter the booth. Children typically prefer that a parent sits next to them inside of the booth, and in some cases the child sits on the parent&#39;s lap.</li>
	<li>Using child-friendly language, give the child and parent an overview of the task. Describe the sound(s) that the child will hear and model the targeted motor response.</li>
	<li>Have the experimenter or the assistant place the insert earphone or supra-aural headphones on the child.
	<ol>
		<li>Position the child at eye-level, and allow the child to see and feel the insert earphone or headphone prior to placement.</li>
		<li>Provide the child with a sense of control by allowing him/her to choose where to clip the transducer or by having the child assist the experimenter in placing the headphones.</li>
		<li>If the child is reluctant to wear headphones, place the transducer on the parent or a doll to model the procedure.</li>
		<li>Terminate the testing session if in the unlikely event that the child is unwilling to wear the transducer or becomes distressed.</li>
	</ol>
	</li>
	<li>If the parent prefers to be in the control room during testing, have the observer escort the parent to the control room. Allow the parent to hear and see the child from the control room.</li>
	<li>Have the assistant verify that the booth door(s) are closed.</li>
	<li>Have the assistant place headphones on his/her ears in order to hear the observer in the control room, as well as the audio prompt marking each interval.</li>
	<li>Have the assistant give the child a toy (e.g., a block) and instruct the child to place the object against his/her torso or cheek. This placement of the toy is called the &#34;ready&#34; position; the child uses this position throughout testing.</li>
	<li>Require the observer to initiate a trial only if the child is in the ready position.</li>
	<li>Have the observer initiate the conditioning stage (Stage 1). The goal of this Stage 1 is to condition the child to make a clear, time-locked motor response when he/she hears the target signal.</li>
	<li>To facilitate learning the task, have the assistant and child initially &#34;listen together&#34; using a hand-over-hand technique.
	<ol>
		<li>Have the assistant place his/her hand on the child&#39;s hand. Have the assistant move the child&#39;s hand when the assistant hears the auditory interval marker for the second interval in his/her headset, because the signal is always present in interval 2 during Stage 1.</li>
		<li>Alternatively, have the assistant perform the task in parallel with the child.</li>
		<li>Have the assistant reduce the level of assistance with subsequent trials.</li>
		<li>If the child is slow to respond, encourage the child to respond as soon as he/she hears the target signal or ask the child to &#34;race&#34; the assistant.</li>
	</ol>
	</li>
	<li>Continue presenting trials in Stage 1 until the observer is confident the child&#39;s responses are under stimulus control.
	<ol>
		<li>Have the observer make this decision based on (1) whether the child is able to perform the motor task without assistance, and (2) whether the child is able to make a fast, time-locked response to the signal that the observer can judge.</li>
		<li>Require a minimum of 3 trials in this stage.</li>
	</ol>
	</li>
	<li>Have the observer initiate Stage 2 of testing. 
	NOTE: In this stage, neither the observer nor the assistant know which test interval contains the signal. The observer must accurately judge 4 out of 5 sequential trials to successfully complete this stage. 
	NOTE: The child is considered trained with the successful completion of Stages 1 and 2. If more than one session is needed, suspend the testing session at this point. It is recommended that testing resumes within two weeks. At the second visit, present a few reminder trials (using Stage 1) prior to initiating Stage 3 of testing.</li>
	<li>Initiate Stage 3 to collect experimental data. As in Stage 2, have the observer closely watch the listener and judge which interval contains the signal. In addition to the motor-based play response, have the observer watch for subtle behaviors.</li>
	<li>NOTE: Children often exhibit subtle behaviors to sound, including eye or head movement, changes in facial expression, and quieting of activity17,18. Have the observer use these subtle behaviors to judge which interval contained the signal when the signal level is near a child&#39;s threshold.</li>
	<li>Have the assistant switch the game every 10-15 trials to maximize the child&#39;s interest and reduce the risk of habituation9. Have the assistant provide frequent social reinforcement to the child to engage the child and to shape and maintain the child&#39;s behavior.</li>
	<li>If the child stops responding in a consistent manner, the child may have &#34;forgotten&#34; what the signal sounds like or may have habituated to the play-based task. Employ the following strategies to increase the child&#39;s participation:
	<ol>
		<li>Have the assistant reinstruct the child and model the response for the child. Have the assistant introduce a new game.</li>
		<li>Provide more reinforcement, either by increasing social reinforcement from the assistant or activating the mechanical toys controlled by the custom software.</li>
	</ol>
	</li>
	<li>For 2 and 3 year-olds, terminate testing after the completion of Stage 3. For children who are 4 years or older, run a second adaptive track if desired. Prior to starting a second track, give children a short break (5-10 min) to play.</li>
	<li>At the conclusion of testing, complete a screening tympanogram to evaluate middle ear functioning. Perform the screening at the end of the visit because some children are more receptive to this procedure after spending time in the test environment and becoming familiar with the testers.</li>
	<li>Compensate the participant and schedule a follow-up visit, if needed.</li>
</ol>
4. Data Analysis
<ol>
	<li>Average the signal level at the last 6 reversals of the adaptive track to calculate the detection threshold.</li>
	<li>Compute the standard deviation of the last 6 reversal levels. In order for a threshold to be considered valid, the standard deviation must be below a criterion established based on pilot data. A high standard deviation indicates that the reversal levels were widely spaced, possibly due to inconsistencies in the observer&#39;s judgements or listeners factors such as training effects, fatigue, or off-task behaviors.</li>
	<li>Calculate the hit rate for probe trials by determining the proportion of probe signal trials that were correctly judged by the observer during Stage 3 of testing. In order for a threshold to be considered valid, the probe hit rate must meet the minimum criterion of 0.80. Failure to meet this criterion is because of inconsistent responses to supra-threshold signals, which may indicate fatigue, off-task behavior, or inadequate training for the listener and/or the observer.</li>
</ol>

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The authors declare that they have no competing financial interests.

This paper described a two-interval, forced-choice behavioral procedure for measuring hearing abilities in 2 to 4 year old children. In this procedure, an observer judges whether the signal is presented in interval 1 or interval 2 based solely on the listener&#39;s behavior. Children&#39;s behavior is shaped to be time-locked to the presentation of the signal by training them to perform a play-based response to the sound. Our preliminary results indicate this method is feasible and reliable for testing the hearing sensitivity of 2 to 4 year-olds.
Significance of the Procedure
There are several advantages associated with this method. The first advantage is that it can be used to test children as young as 2.0 years developmental age. Thresholds were successfully measured for 5 out of the 8 2-year-olds. A similar yield rate (~60-70%) has been reported in the literature for the measurement of hearing sensitivity in 2-year-olds using conditioned-play audiometry in the soundfield9,21. As with conditioned-play audiometry7,8, thresholds were successfully measured for all but one of the 3 year-olds, and all 4 year-olds. The second advantage of this method is that it guards against observer response bias. The observer must base his/her judgments solely on the child&#39;s behavior, so prior expectations regarding the child&#39;s sensitivity or behavior do not affect the results. The third advantage of this method is that it may be easier for the observer to judge which interval contains the signal than to make a yes-no decision regarding the presence or absence of a signal. In the present two-interval task, the observer is able to compare the child&#39;s behavior across the two intervals rather than comparing behavior across multiple trials, as is required in the single-interval task. Thus, the memory load on the observer may be smaller for the two-interval relative to the single-interval task. Moreover, looking for time-locked changes in behavior may allow the observer to adapt to changes in the child&#39;s behavior that occur during the testing session.
Limitations
There are a few limitations to consider when applying this method. First, pilot data are required to determine the appropriate parameters &#8211; training criteria, starting level, inter-stimulus interval value, and transducer &#8211; to use for different age groups and stimuli. In particular, adjusting testing parameters may affect the number of 2 year-olds who can successfully do the task and provide useable experimental data. Yield rate for 2 year-olds may be improved by presenting stimuli through the soundfield or headphones rather than an insert earphone. However, precautions must be taken when performing testing in the soundfield to prevent the assistant and parent from hearing the signal (see Leibold et al.22 for specifics.) A longer inter-stimulus interval may be required for younger children than for older children, if younger listeners take longer to complete the play-based response. Also, 2 year-olds may require greater training and may fatigue faster than older children. In order to guard against fatigue, it is recommended to change toys frequently9 and provide frequent breaks in testing. Recall that we tested three of the youngest children over two visits, rather than one. Second, it is not clear how much experience is required for observers and assistants to obtain reliable results using this procedure. In this example, all observers and assistants had at least two years of experience testing toddlers and preschoolers in the audiology clinic using play-based audiometry, as well as at least one additional year of experience in the laboratory testing infants and/or school-aged children. It is recommended to establish protocols for training new observers and to ensure consistent performance for trained observers. Further research is needed to determine the reliability of this method across observers and laboratories.
Future Applications
It may be possible to modify this procedure to test children who are unable to perform conventional motor responses. For example, the conditioned response could be an eye movement, head turn, or a change in activity level14. Previous work has shown that trained observers can reliably use these alternative behaviors to test infants as young as 1 month of age using a single-interval, observer-based method23. Furthermore, the single-interval, observer-based method has been used to measure hearing sensitivity in special populations, including 2 to 12 month-olds with Down Syndrome24 and 26 to 36 month-olds with cochlear implants25. Results from these previous studies support the feasibility of testing children who cannot produce a play-based, motor response with a two-interval paradigm.
Whereas the current study evaluated detection thresholds in quiet, this procedure can also be used to evaluate masked detection or discrimination. In the case of masking noise, previous studies of infants tested with the single-interval, observer-based procedure suggest that the masker be played continuously over the course of an adaptive track in order to avoid responses to masker onsets and/or offsets26. Similarly, to evaluate discrimination abilities, a standard sound is presented repeatedly apart from the signal interval, during which the signal stimulus would be presented27. For all stimulus conditions, the listener would be conditioned to respond when he/she detects a change in the stimulus, whether that change is the addition of a sound (detection) or a change in the sound (discrimination). While the current study used an adaptive procedure to estimate threshold, the same procedures could be used to evaluate percent correct performance at a fixed signal and/or masker level. Another possible modification is that the stimuli can be presented through other transducers, including the soundfield13,22.
In summary, the play-based, two-interval procedure described here provides reliable behavioral data on the hearing abilities of toddlers and preschoolers. Using this method, researchers will be able to study how the auditory system changes during the toddler and preschooler years &#8211; a time period where we know little about auditory behavior.

It is difficult to obtain reliable estimates of behavioral hearing thresholds for toddlers and preschoolers. The operant techniques used to test infants in the clinic and the laboratory do not generally work well with children in this age range because toddlers and preschoolers tend to habituate faster than infants1,2. On the other hand, toddlers and preschoolers often lack the cognitive maturity required to complete standard forced-choice behavioral testing procedures that are used to evaluate children 4 years of age and older3,4. Consequently, there are significant gaps in our understanding of human auditory development between infancy and early school age.
A single-interval, adaptive procedure called Conditioned Play Audiometry5 (CPA) is routinely used in the audiology clinic to assess hearing sensitivity for children with a developmental age falling between about 2.5 and 5 years6. CPA relies on the use of a play-based motor activity (e.g., stacking blocks) to establish a time-locked conditioned response to an auditory signal. A test assistant provides the child with positive social reinforcement, further shaping the response behavior. Results from several studies have shown that the use of CPA yields a conventional clinical audiogram for more than 90% of typically developing 3 year-olds7,8. Substantially lower yield rates have been reported for younger children. For example, Thompson et al.9 reported that a conditioned response to sound could be established using CPA in 68% of 2 year-olds.
Despite the widespread use of CPA in the audiology clinic, it is not well suited for most laboratory-based investigations of auditory behavior. CPA is a single-interval adaptive procedure designed to maximize both efficiency and patient acceptance, but it is susceptible to observer and listener response bias. The observer in the CPA procedure initiates signal presentations, and may thus be influenced by factors such as a priori expectations regarding the child&#39;s hearing sensitivity or their propensity to respond10. The inclusion of &#34;catch&#34; trials &#8211; trials in which no sound is presented - is sometimes used to quantify and accommodate examiner response bias11.
The overall goal of the method described in the present report is to efficiently estimate hearing thresholds in toddlers and preschoolers using a play-based, two-interval, forced-choice behavioral testing procedure. The rationale for using a forced-choice paradigm is that it guards against some forms of response bias10, thus permitting more direct comparisons across different ages and/or stimuli using an efficient adaptive procedure. Conventional two- and three-interval, forced-choice methods require a specific, prescribed response (e.g., pushing one of several buttons) on the part of the listener, to indicate which interval contains the signal. Children as young as 4 to 5 years of age can perform this task12, but the demands of the procedure make these methods unsuitable for younger listeners and for many listeners with developmental delays.
The method described here builds on the work of Browning et al.13, which evaluated the feasibility and efficiency of estimating infant behavioral thresholds using a two-interval, forced-choice adaptation of the observer-based psychophysical procedure14. In this method, the signal is presented during one of two observation intervals. Each interval is indicated to the observer in real time both visually and acoustically, but the observer is not told which interval contains the signal. The infant, on the other hand, is not given any indication of the occurrence of an observation interval apart from the presentation of a signal. After each trial, the observer selects the interval containing the signal based on the infant&#39;s behavior. The results reported by Browning et al.13 demonstrated that this procedure is both feasible and efficient for use with 7 to 9 month-old infants. The method for testing toddlers and preschoolers closely follows procedures for testing infants, with the caveat that children&#39;s responses to sound are shaped using methods common with CPA.
For this article, a simple experiment was designed to measure children&#39;s tone detection in quiet. The signal was a 500 msec, 1,000 Hz warble tone presented through an insert earphone. Note that we have also successfully used this protocol to assess performance in more complex listening tasks, such as speech detection in a noise masker15. In the protocol described below, children are taught to perform a play-based conditioned motor response when a signal is heard. However, any behavioral response can be used, provided it is time-locked to the presentation of the stimulus and can be reliably judged. As demonstrated here, this task is appropriate for testing typically developing children as young as 2 years of age.

<table><tbody><tr><td>RZ6 auditory processor</td><td>Tucker-Davis Technologies (TDT)</td><td></td><td></td></tr><tr><td>ER1 insert earphone</td><td>Etymotic Research</td><td></td><td></td></tr><tr><td>IntellegentVRA mechanical toys and control box</td><td>Intelligent Hearing Systems</td><td></td><td>System modified by company to interface with TDT system</td></tr></tbody></table>

behavioral assessment of hearing in 2 to 4 year-old children: a two-interval, observer-based procedure using conditioned play-based responses

Collecting reliable behavioral data from toddlers and preschoolers is challenging. As a result, there are significant gaps in our understanding of human auditory development for these age groups. This paper describes an observer-based procedure for measuring hearing sensitivity with a two-interval, two-alternative forced-choice paradigm. Young children are trained to perform a play-based, motor response (e.g., putting a block in a bucket) whenever they hear a target signal. An experimenter observes the child&#39;s behavior and makes a judgment about whether the signal was presented during the first or second observation interval; the experimenter is blinded to the true signal interval, so this judgment is based solely on the child&#39;s behavior. These procedures were used to test 2 to 4 year-olds (n = 33) with no known hearing problems. The signal was a 1,000 Hz warble tone presented in quiet, and the signal level was adjusted to estimate a threshold corresponding to 71%-correct detection. A valid threshold was obtained for 82% of children. These results indicate that the two-interval procedure is both feasible and reliable for use with toddlers and preschoolers. The two-interval, observer-based procedure described in this paper is a powerful tool for evaluating hearing in young children because it guards against response bias on the part of the experimenter.

Thirty-three children were recruited from a database of children who are typically-developing, based on parental report. Inclusion criteria included no known history of hearing loss, no more than three episodes of otitis media, and no episodes of otitis media in the month prior to testing. Eight 2 year-olds, eighteen 3 year-olds, and seven 4 year-olds met these inclusion criteria. Of the children recruited, three would not tolerate the insert earphone and testing was not attempted.
Of the remaining 30 children, all but one child (a 2 year-old) successfully completed both training stages (Stage 1 and Stage 2). On average, children required 4.8 trials (SD = 2.4; max = 12) in Stage 1 and 4.1 trials (SD = 0.3; max = 5) in Stage 2. Two 2 year-olds and one 3 year-old were only able to complete training during the first visit; two of these children returned for a second visit and successfully completed Stage 3. All remaining children completed the protocol in a single session. On average, children required 40.0 trials to complete Stage 3 (SD = 7.9; min = 27; max = 57). All 28 children who completed Stage 3 of testing met the probe rate criterion of &#8805;0.80; all probe signal trials were correctly identified in 75% of testing sessions. Only one child&#39;s data were excluded based on excessive variability; in this case, the standard deviation of reversal values exceeded the criterion of 4.4 dB.
Figure 2 shows individual children&#39;s thresholds as a function of age. Thresholds for all children with normal middle ear functioning, based on tympanometry on the day of testing, are shown by the open circles. Six additional children (21%) had abnormal tympanograms, indicating possible middle ear dysfunction (e.g., middle ear fluid). Data shown with filled symbols indicate abnormal middle ear function based on tympanometry: reduced compliance (Type B; square) or excessive negative pressure (Type C; triangle). One additional child would not tolerate the test procedure for screening tympanometry, so his middle ear status is unknown (diamond). Interpret threshold values from children with abnormal middle ear function cautiously because abnormal middle ear status is associated with elevated thresholds19. Thresholds obtained from children are broadly consistent with previous data on this age group. For example, Schneider at al.20 estimated psychometric functions for detecting an octave-wide band of noise at 1,000 Hz in preschoolers. Defining threshold as the level associated with 65% correct, the mean threshold was approximately 21 dB SPL for 3 year-olds and 14 dB SPL for 4 year-olds.
<img alt="Figure 2" src="/files/ftp_upload/54788/54788fig2.jpg" /> 
Figure 2: Warble-tone detection thresholds. Detection thresholds are plotted as a function of child age. Only the first threshold obtained from each listener is shown. Symbol shape reflects the middle ear status of the listener: Type A (circle), Type B (square), Type C (triangle), or could not test (CNT; diamond). Whereas Type A indicates normal middle ear admittance, Type B (flat) and Type C (negative pressure) are typically associated with reduced middle ear function due to fluid, congestion, or ear infection. <a href="http://cloudflare.jove.com/files/ftp_upload/54788/54788fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Thresholds were also measured for a group of young adults with normal hearing sensitivity and middle ear status on the day of testing (n = 8; 20-25 years). Due to procedural modifications between the two age groups, caution is warranted when comparing the child and adult data. The primary protocol difference between the two age groups was that an assistant inside of the booth was not present when testing adults. In contrast to children who were provided reinforcement through social engagement with the assistant, adults were provided only with trial-by-trial feedback through the activation of mechanical toys. Adults completed two consecutive adaptive tracks in a single testing session. However, only the threshold from the first adaptive track run was considered here. The mean adult threshold for the warble stimulus was 2.4 dB SPL (SD = 1.7 dB). In the present study, the group difference in threshold between adults and the 3 year-olds, with normal middle ear function, was 7.2 dB. This observed child-adult difference is smaller than has been reported in some studies20. However, the magnitude of the child-adult difference is likely influenced by both the overall procedure and any procedural modifications implemented between children and adults. Further research is needed to better understand how children&#39;s and adults&#39; sensitivity to the stimulus is affected by modifications to the two-interval, observer-based procedure described in this paper.

Watch this Scientific Journal Video about Behavioral Assessment of Hearing in 2 to 4 Year-old Children: A Two-interval, Observer-based Procedure Using Conditioned Play-based Responses at JoVE.com

Behavioral Assessment of Hearing in 2 to 4 Year-old Children: A Two-interval, Observer-based Procedure Using Conditioned Play-based Responses

This paper describes a procedure for measuring hearing sensitivity in 2 to 4 year-old children. Children are trained to perform play-based responses when they hear a target signal. Thresholds are then estimated in a two-interval, two-alternative forced-choice paradigm, based on observations of the child&#39;s behaviors.

Collecting reliable behavioral data from toddlers and preschoolers is challenging. As a result, there are significant gaps in our understanding of human ...

behavioral-assessment-hearing-2-to-4-year-old-children-two-interval

Research

JoVE Journal

Behavior

29.0K Views.  The University of North Carolina at Chapel Hill. This paper describes a procedure for measuring hearing sensitivity in 2 to 4 year-old children. Children are trained to perform play-based responses when they hear a target signal. Thresholds are then estimated in a two-interval, two-alternative forced-choice paradigm, based on observations of the child's behaviors.

Video: Behavioral Assessment of Hearing in 2 to 4 Year-old Children: A Two-interval, Observer-based Procedure Using Conditioned Play-based Responses

Making Sense of Listening: The IMAP Test Battery

The ability to hear is only the first step towards making sense of the range of information contained in an auditory signal. Of equal importance are the abilities to extract and use the information encoded in the auditory signal. We refer to these as listening skills (or auditory processing AP). Deficits in these skills are associated with delayed language and literacy development, though the nature of the relevant deficits and their causal connection with these delays is hotly debated.
When a child is referred to a health professional with normal hearing and unexplained difficulties in listening, or associated delays in language or literacy development, they should ideally be assessed with a combination of psychoacoustic (AP) tests, suitable for children and for use in a clinic, together with cognitive tests to measure attention, working memory, IQ, and language skills. Such a detailed examination needs to be relatively short and within the technical capability of any suitably qualified professional. Current tests for the presence of AP deficits tend to be poorly constructed and inadequately validated within the normal population. They have little or no reference to the presenting symptoms of the child, and typically include a linguistic component. Poor performance may thus reflect problems with language rather than with AP. To assist in the assessment of children with listening difficulties, pediatric audiologists need a single, standardized child-appropriate test battery based on the use of language-free stimuli.
We present the IMAP test battery which was developed at the MRC Institute of Hearing Research to supplement tests currently used to investigate cases of suspected AP deficits. IMAP assesses a range of relevant auditory and cognitive skills and takes about one hour to complete. It has been standardized in 1500 normally-hearing children from across the UK, aged 6-11 years. Since its development, it has been successfully used in a number of large scale studies both in the UK and the USA. IMAP provides measures for separating out sensory from cognitive contributions to hearing. It further limits confounds due to procedural effects by presenting tests in a child-friendly game-format. Stimulus-generation, management of test protocols and control of test presentation is mediated by the IHR-STAR software platform. This provides a standardized methodology for a range of applications and ensures replicable procedures across testers. IHR-STAR provides a flexible, user-programmable environment that currently has additional applications for hearing screening, mapping cochlear implant electrodes, and academic research or teaching.

A test battery (IMAP) for performing an in-depth assessment of auditory and cognitive abilities contributing to listening skills is described. It is quick to administer, child-friendly and free from linguistic confounds. Stimulus generation and protocol management are controlled via a software platform (IHR-STAR) to ensure replicable procedures.

The ability to hear is only the first step towards making sense of the range of information contained in an auditory signal. Of equal importance are the ...

Medicine

Quantitative Assessment of Cortical Auditory-tactile Processing in Children with Disabilities

Objective and easy measurement of sensory processing is extremely difficult in nonverbal or vulnerable pediatric patients. We developed a new methodology to quantitatively assess children&#39;s cortical processing of light touch, speech sounds and the multisensory processing of the 2 stimuli, without requiring active subject participation or causing children discomfort. To accomplish this we developed a dual channel, time and strength calibrated air puff stimulator that allows both tactile stimulation and sham control. We combined this with the use of event-related potential methodology to allow for high temporal resolution of signals from the primary and secondary somatosensory cortices as well as higher order processing. This methodology also allowed us to measure a multisensory response to auditory-tactile stimulation.

Objective and easy measurement of sensory processing is extremely difficult in nonverbal or vulnerable pediatric patients. We developed a new methodology to quantitatively assess infants and children&#39;s cortical processing of light touch, speech sounds, and the multisensory processing of the 2 stimuli, without requiring active subject participation or causing discomfort in vulnerable patients.

Objective and easy measurement of sensory processing is extremely difficult in nonverbal or vulnerable pediatric patients. We developed a new methodology ...

Infant Auditory Processing and Event-related Brain Oscillations

Rapid auditory processing and acoustic change detection abilities play a critical role in allowing human infants to efficiently process the fine spectral and temporal changes that are characteristic of human language. These abilities lay the foundation for effective language acquisition; allowing infants to hone in on the sounds of their native language. Invasive procedures in animals and scalp-recorded potentials from human adults suggest that simultaneous, rhythmic activity (oscillations) between and within brain regions are fundamental to sensory development; determining the resolution with which incoming stimuli are parsed. At this time, little is known about oscillatory dynamics in human infant development. However, animal neurophysiology and adult EEG data provide the basis for a strong hypothesis that rapid auditory processing in infants is mediated by oscillatory synchrony in discrete frequency bands. In order to investigate this, 128-channel, high-density EEG responses of 4-month old infants to frequency change in tone pairs, presented in two rate conditions (Rapid: 70 msec ISI and Control: 300 msec ISI) were examined. To determine the frequency band and magnitude of activity, auditory evoked response averages were first co-registered with age-appropriate brain templates. Next, the principal components of the response were identified and localized using a two-dipole model of brain activity. Single-trial analysis of oscillatory power showed a robust index of frequency change processing in bursts of Theta band (3 - 8 Hz) activity in both right and left auditory cortices, with left activation more prominent in the Rapid condition. These methods have produced data that are not only some of the first reported evoked oscillations analyses in infants, but are also, importantly, the product of a well-established method of recording and analyzing clean, meticulously collected, infant EEG and ERPs. In this article, we describe our method for infant EEG net application, recording, dynamic brain response analysis, and representative results.

High-density electroencephalography (dEEG) is being used increasingly to study brain development and plasticity in the early years of life. Here we present an application of sophisticated analysis techniques that builds on traditional EEG recording to understand the oscillatory dynamics of rapid auditory processing in the infant brain.

Rapid auditory processing and acoustic change detection abilities play a critical role in allowing human infants to efficiently process the fine spectral ...

Testing Sensory and Multisensory Function in Children with Autism Spectrum Disorder

In addition to impairments in social communication and the presence of restricted interests and repetitive behaviors, deficits in sensory processing are now recognized as a core symptom in autism spectrum disorder (ASD). Our ability to perceive and interact with the external world is rooted in sensory processing. For example, listening to a conversation entails processing the auditory cues coming from the speaker (speech content, prosody, syntax) as well as the associated visual information (facial expressions, gestures). Collectively, the &#8220;integration&#8221; of these multisensory (i.e., combined audiovisual) pieces of information results in better comprehension. Such multisensory integration has been shown to be strongly dependent upon the temporal relationship of the paired stimuli. Thus, stimuli that occur in close temporal proximity are highly likely to result in behavioral and perceptual benefits &#8211; gains believed to be reflective of the perceptual system&#39;s judgment of the likelihood that these two stimuli came from the same source. Changes in this temporal integration are expected to strongly alter perceptual processes, and are likely to diminish the ability to accurately perceive and interact with our world. Here, a battery of tasks designed to characterize various aspects of sensory and multisensory temporal processing in children with ASD is described. In addition to its utility in autism, this battery has great potential for characterizing changes in sensory function in other clinical populations, as well as being used to examine changes in these processes across the lifespan.

We describe how to implement a battery of behavioral tasks to examine the processing and integration of sensory stimuli in children with ASD. The goal is to characterize individual differences in temporal processing of simple auditory and visual stimuli and relate these to higher order perceptual skills like speech perception.

In addition to impairments in social communication and the presence of restricted interests and repetitive behaviors, deficits in sensory processing are ...

Portable Intermodal Preferential Looking (IPL): Investigating Language Comprehension in Typically Developing Toddlers and Young Children with Autism

One of the defining characteristics of autism spectrum disorder (ASD) is difficulty with language and communication.1 Children with ASD's onset of speaking is usually delayed, and many children with ASD consistently produce language less frequently and of lower lexical and grammatical complexity than their typically developing (TD) peers.6,8,12,23 However, children with ASD also exhibit a significant social deficit, and researchers and clinicians continue to debate the extent to which the deficits in social interaction account for or contribute to the deficits in language production.5,14,19,25
Standardized assessments of language in children with ASD usually do include a comprehension component; however, many such comprehension tasks assess just one aspect of language (e.g., vocabulary),5 or include a significant motor component (e.g., pointing, act-out), and/or require children to deliberately choose between a number of alternatives. These last two behaviors are known to also be challenging to children with ASD.7,12,13,16
We present a method which can assess the language comprehension of young typically developing children (9-36 months) and children with autism.2,4,9,11,22 This method, Portable Intermodal Preferential Looking (P-IPL), projects side-by-side video images from a laptop onto a portable screen. The video images are paired first with a 'baseline' (nondirecting) audio, and then presented again paired with a 'test' linguistic audio that matches only one of the video images. Children's eye movements while watching the video are filmed and later coded. Children who understand the linguistic audio will look more quickly to, and longer at, the video that matches the linguistic audio.2,4,11,18,22,26
This paradigm includes a number of components that have recently been miniaturized (projector, camcorder, digitizer) to enable portability and easy setup in children's homes. This is a crucial point for assessing young children with ASD, who are frequently uncomfortable in new (e.g., laboratory) settings. Videos can be created to assess a wide range of specific components of linguistic knowledge, such as Subject-Verb-Object word order, wh-questions, and tense/aspect suffixes on verbs; videos can also assess principles of word learning such as a noun bias, a shape bias, and syntactic bootstrapping.10,14,17,21,24 Videos include characters and speech that are visually and acoustically salient and well tolerated by children with ASD.

Portable Intermodal Preferential Looking IPL: Investigating Language Comprehension in Typically Developing Toddlers and Young Children with Autism

A reliable home-based way to assess the language comprehension of very young typically developing children, as well as those with autism, is described. The method analyzes children's eye gaze while viewing side-by-side images but hearing an audio that matches only one image. Stimuli are designed with young participants in mind.

One  of the defining characteristics of autism spectrum disorder (ASD) is difficulty  with language and communication.1  Children with ASD's onset of ...

An Electrophysiology Protocol to Measure Reward Anticipation and Processing in Children

We present a protocol designed to measure the neural correlates of reward in children. The protocol allows researchers to measure both reward anticipation and processing. Its purpose is to create a reward task that is appropriate for young children with and without autism while controlling reward properties between two conditions: social and nonsocial. The current protocol allows for comparisons of brain activity between social and nonsocial reward conditions while keeping the reward itself identical between conditions. Using this protocol, we found evidence that neurotypical children demonstrate enhanced anticipatory brain activity during the social condition. Furthermore, we found that neurotypical children anticipate social reward more robustly than children with autism diagnoses. As the task uses snacks as a reward, it is most appropriate for young children. However, the protocol may be adapted for use with adolescent or adult populations if snacks are replaced by monetary incentives. The protocol is designed to measure electrophysiological events (event-related potentials), but it may be customized for use with eye-tracking or fMRI.

This protocol is designed to measure reward anticipation and processing in young children with and without autism. Specifically, the protocol is designed to study the neural correlates of reward during social and nonsocial conditions while controlling for reward between conditions.

We present a protocol designed to measure the neural correlates of reward in children. The protocol allows researchers to measure both reward anticipation ...

Systematic Hearing Performance Evaluation Process for Adolescents with Cochlear Implantation at Early Ages

Cochlear implant (CI) provision is the most effective clinical treatment to restore hearing performance in individuals with profound sensorineural hearing loss (SNHL). It has been successful in providing improved speech perception outcomes, especially in quiet environments. However, speech perception performance within complex environments, lexical tone recognition, and music perception have been shown to only improve with newer fine structure coding strategies or related techniques. Therefore, the methods used to assess hearing performance in noisy environments, lexical tone recognition, and music perception are of vital importance. These assessments must reflect the postoperative outcomes and also provide guidance for the programming, rehabilitation, and application of new coding strategies. In this study, hearing performance in simple and complex situations was evaluated before and after upgrading to a fine structure strategy. The participants were a cohort of Mandarin-speaking adolescents, who were experienced CI users. The comprehensive clinical workflow involved assessments of speech in quiet conditions, speech in noisy conditions, lexical tone recognition, and music perception. This battery of tests is explained in detail, from the coding strategy to the test methods, including the test process, environment, device, material, and order. The details that require special attention are discussed, such as the position of the participants, the angle of the loudspeaker, the intensity of the sound, the noise type, the practice test, and the way of answering questions. Each test step, method, and material for speech, lexical tone, and music perception is presented in detail. Finally, the clinical results are discussed.

This paper describes a battery of tests used to clinically assess the hearing performance of adolescent, Mandarin-speaking, experienced cochlear implant users upgraded to a new fine structure coding strategy. The battery of tests include speech in quiet conditions, speech in noisy conditions, lexical tone, and music perception.

Cochlear implant (CI) provision is the most effective clinical treatment to restore hearing performance in individuals with profound sensorineural hearing ...

Toddler and Preschool Child Exam

Source: Heather Collette&#160;and Jaideep Talwalkar; Yale School of Medicine
The key to a successful exam of a toddler or preschool-age child is building rapport and trust between them and the provider. Toddlers, in particular, may be wary of strangers and unwilling to cooperate with the physical exam, which is expected age-appropriate behavior. In order to provide good care and create a comfortable patient experience, clinicians need to tailor their interaction to the child&#39;s developmental stage. Ensuring positive medical encounters for children will increase their likelihood of seeking medical care as they age into adulthood. Clinicians must be creative and flexible as they work with children to achieve their care goals. Suggestions on how to facilitate these interactions will be covered in this video, with less of a focus on specific organ system components, as these are similar to other age groups.
Toddlerhood through preschool age is a time of significant physical and developmental growth. Progression of language, motor, and social skills is a reflection of children&#39;s brain growth and social environment. Normal development follows a typical progression, but exact time points for achieving developmental milestones can vary among children. Achieving a specific milestone a few months later than another child or based on a time point listed on a development chart does not necessarily indicate a problem. Providers must ensure that children meet developmental milestones as expected and, if not, refer them early for special services to promote the best outcome possible.&#160;

Source: Heather Collette&#160;and Jaideep Talwalkar; Yale School of Medicine
The key to a successful exam of a toddler or preschool-age child is building ...

Education

JoVE Science Education

Clinical Skills

Physical Examinations IV

The Costs and Benefits of Natural Pedagogy

Source: Laboratories of Nicholaus Noles, Judith Danovitch, and Asheley Landrum&#8212;University of Louisville
Children have many tools they use over the course of development to learn from adults. Perhaps the earliest tool is imitation, simply copying what they see an adult do or say. However, children actually learn much more effectively than one might expect if they were only imitating. This is because, when it comes to learning and teaching, children and adults have a special relationship. Children treat adults as if they are helpful and knowledgeable teachers, and adults teach children information in a manner that is usually efficient and effective. Through these interactions, children can learn much better than if they were simply using trial-and-error or copying adults exactly. This way of interacting is referred to as natural pedagogy, and it is one of the reasons that young humans are gifted learners.
One of the most impressive aspects of natural pedagogy is that no one teaches adults how to be good teachers, and children treat adults as teachers without having to be trained to do so. However, natural pedagogy also entails costs. Children are curious and intrinsically motivated to explore, so children do some of their best learning when given opportunities to learn and explore on their own. Thus, the result of natural pedagogy is that children learn information taught to them very effectively, but explicit teaching restricts their curious, exploratory behaviors. There is a tradeoff between efficient learning and self-driven exploration.
This video demonstrates the method by which Elizabeth Bonawitz, Patrick Shafto, and colleagues1 showed the effects of natural pedagogy on young learners.

Investigating the Benefits and Limitations of Natural Pedagogy

Source: Laboratories of Nicholaus Noles, Judith Danovitch, and Asheley Landrum&#8212;University of Louisville
Children have many tools they use over the ...

Psychology

Developmental Psychology

Piaget's Conservation Task and the Influence of Task Demands

Source: Laboratories of Judith Danovitch and Nicholaus Noles&#8212;University of Louisville
Jean Piaget was a pioneer in the field of developmental psychology, and his theory of cognitive development is one of the most well-known psychological theories. At the heart of Piaget&#8217;s theory is the idea that children&#8217;s ways of thinking change over the course of childhood. Piaget provided evidence for these changes by comparing how children of different ages responded to questions and problems that he designed.
Piaget believed that at age 5, children lack mental operators or logical rules, which underlie the ability to reason about relationships between sets of properties. This characteristic defined what he called the preoperational stage of cognitive development. One of Piaget&#8217;s classic measures of children&#8217;s ability to use mental operations is his conservation task. In this task, children are shown two identical objects or sets of objects. Children are first shown that the objects are the same on one key property (number, size, volume, etc.). Then, one of the objects is modified so it appears different than the other one (e.g., it is now longer, wider, or taller), but the key property remains the same. Following this transformation, children are asked to judge if the two objects or sets of objects are now the same or different with respect to the original key property.
Piaget reported that children in the preoperational stage (approximately ages 2-7) typically judged the objects to be different after the transformation, even though the key property had not changed. He attributed children&#8217;s incorrect responses to their excessive focus on the change, rather than on the fact that the key property remained the same. However, over the years, researchers have argued that Piaget&#8217;s conservation task is an invalid measure of children&#8217;s reasoning skills. These critics have suggested that children&#8217;s poor performance is due to task demands, such as assumptions about the experimenter&#8217;s goals and expectations when the question about the key property is repeated.
This video demonstrates how to conduct Piaget&#8217;s classic conservation task,1&#8211;2 and how a small modification in the task design can dramatically change children&#8217;s accuracy (based on the methods developed by McGarrigle and Donaldson3).

Piaget&#039;s Conservation Task and the Influence of Task Demands

Source: Laboratories of Judith Danovitch and Nicholaus Noles&#8212;University of Louisville
Jean Piaget was a pioneer in the field of developmental ...