This work was partially supported by a grant from JSPS KAKENHI Grant Number JP17K00209. The author thanks Takayuki Hoshino and Kazuhiro Shigeta for technical assistance.

All methods described here have been approved by the Ethics Committee of Tokyo Denki University. For every participant, informed consent was obtained after the participant received a detailed explanation of the protocol.
1. Setup of the Left-Right Reversed Audition System
<ol>
	<li>Setup of the Reversed Audition System without a Participant 
	<ol>
		<li>Prepare a linear pulse-code-modulation (LPCM) recorder, binaural microphones, and binaural in-ear earphones.</li>
		<li>Connect the left and right lines of the microphones crossly to the LPCM recorder so that left-right reversed analogue sound signals are digitalized. Moreover, connect the left and right lines of the earphones straight through to the recorder so that the reversed digitalized signals are immediately played. 
		NOTE: In the case of employing the binaural earphone-microphones as binaural earphones, do not use the earphone parts in order to reduce the spillover of the sounds that go through the microphone parts.</li>
		<li>Put the bodies of the microphones and the earphones together for each ear with slight isolation by sound proofing materials, and cover the microphones with dedicated windscreens for suppressing the wind noise.</li>
		<li>Insert rechargeable batteries and a large-capacity high-speed memory card into the LPCM recorder and turn it on. Set the recording conditions properly in such a manner that the sound signals are recorded on the memory card as an LPCM format at a sampling rate of 96 kHz with a 24-bit depth.</li>
		<li>Place the body of the system into a pocket-sized bag.</li>
	</ol>
	</li>
	<li>Setup of the Reversed Audition System with a Participant 
	<ol>
		<li>Instruct a participant to insert the earphones of the reversed audition system tightly into the ear canals.</li>
		<li>Disconnect the lines for the left and right microphones and connect the dominant-ear side of the microphone straight through to the recorder.</li>
		<li>Instruct the participant to take off and put on the dominant-ear side of the system repetitively while adjusting the sound volume of the recorder to make the subjective loudness of direct (normal) and indirect (reversed) sounds equal (as close as possible).</li>
		<li>Check the loudness for the non-dominant ear as well, and connect all the lines of the system back again.</li>
		<li>Place the system into the participant&#8217;s pocket, fix the cords on the participant&#8217;s clothes appropriately to prevent them from becoming entangled, and pick up unwanted noises.</li>
	</ol>
	</li>
</ol>
2. Validation of the Left-Right Reversed Audition System
NOTE: Perform the following steps to validate the left-right reversed audition system, irrespective of experiments studying adaptation to left-right reversal.
<ol>
	<li>Validation of the Sound Source Localization of the Reversed Audition System
	<ol>
		<li>Locate a digital angle protractor whose initial direction is defined as 0&#176; at the center of an anechoic room, and assume a virtual circle centered at this point with a radius of 2 m. Along the virtual circle, mark 72 possible sound sources at every 5&#176; from -180&#176; to 175&#176; in a clockwise manner, and set up plane-wave speakers at these points directed towards the center of the circle.</li>
		<li>Set up a video camera near the center of the room to record the display of the digital protractor. 
		NOTE: Since the display of the protractor moves with the protractor&#8217;s body, the field of view of the video should be large enough to cover all the possible areas. Moreover, the video camera should be carefully placed in order to not disturb the participant&#8217;s sitting position and the sound presentation.</li>
		<li>Prepare for two sessions of sound source localization: in the first session, the participant does not put on the reversed audition system. In the second session, the participant puts on the equipment, calibrates it, and checks the system (as explained in step 1.2) as quickly as possible.</li>
		<li>Guide the participants to sit comfortably and blindfolded at the center of the circle facing a 0&#176;&#160;sound source and wait for the experiment to start.</li>
		<li>Conduct two sessions of sound source localization. In both sessions, have the participant use the protractor to indicate the perceived sound direction as precisely as possible without moving the head.</li>
		<li>For each session, start video-recording the angle display of the protractor, and present 1000-Hz sounds at 65-dB sound pressure level (SPL) from any of the sound sources: the sound at one location is randomly switched to the sound at another location every 10 s in such a way that each location is used once. 
		NOTE: Here we use MATLAB with the Psychophysics Toolbox16,17,18. Although this toolbox is commonly used to present sounds, any reliable stimulation software can also be used.</li>
		<li>After each session, stop the video-recording and instruct the participants to take a break for sufficient amount of time.</li>
		<li>Read the trial-by-trial perceptual angles displayed on the protractor from the recorded video, and evaluate the spatial performance of the reversed audition system by comparing the perceptual angles in the normal and the reversed conditions against the physical angles defined by the direction of sound sources.</li>
	</ol>
	</li>
	<li>Validation of the Delay of the Reversed Audition System
	<ol>
		<li>Put the reversed audition system on a desk in a calm room with no participants.</li>
		<li>Disconnect a line to the left microphone, and place a plane-wave speaker and the left earphone as close as possible to the right microphone.</li>
		<li>Start recording direct (normal) sounds from the speaker and indirect (reversed) sounds from the left earphone simultaneously through the right microphone.</li>
		<li>Present 1-ms click sounds from the speaker with a moderate inter-stimulus interval at 65-dB SPL.</li>
		<li>After a sufficient number of trials, stop presenting and recording the sounds.</li>
		<li>In order to confirm the symmetrical configuration of the system, repeat the same steps above using the right earphone and the left microphone.</li>
		<li>Read the recorded sound data using software (e.g., MATLAB) and evaluate the difference between the onset timings of the direct (normal) sounds and indirect (reversed) sounds, which corresponds to a potential delay caused by the time spent passing through the electrical path in the system.</li>
	</ol>
	</li>
</ol>
3. Studying the Adaptation to Left-Right Reversed Audition
<ol>
	<li>Procedure of the Exposure to Reversed Audition
	<ol>
		<li>Remind the participants repeatedly of their right to quit the exposure at any time. 
		NOTE: Stop the exposure as soon as possible if the participant reports sickness or if an observer notices any sign that the participant wants to quit the exposure for any reason.</li>
		<li>Prepare a sufficient number of spare rechargeable batteries and large-capacity high-speed memory cards to allow the participant to replace them at anytime.</li>
		<li>Instruct the participant to wear, calibrate, and check the reversed audition system by themselves during the exposure period, as explained in step 1.2. Perform the same procedure each time the participant wears the system after each interruption.</li>
		<li>Instruct the participant to perform daily-life activities while wearing the system continuously for approximately a month, except while sleeping, bathing, neuroimaging, and other emergency times. In these cases, ask participants to remove the system and immediately insert earplugs into their ears to prevent recovery of adaptation. 
		NOTE: Although it is ideal for the participant to wear the system all day and night, it is strongly recommended that the system not be worn while sleeping and bathing in order to prevent unexpected loud noises and electrical shocks, respectively.</li>
		<li>Replace the batteries and memory cards routinely before battery exhaustion and memory overcapacity, respectively. Remove the system and replace it with earplugs quickly in a silent place without producing any sound.</li>
		<li>When a participant needs to move around outside, drive the participant in a car, accompany the participant on the move, or ask them to use safe means of transportation for acts performed alone. 
		NOTE: Great care should be taken by the researcher in order to not endanger the participant&#8217;s safety during the exposure period, especially when the participant goes outside. Prohibit the participant from performing any dangerous behaviors.</li>
		<li>In order to facilitate adaptation, instruct the participant to experience situations involving high auditory input, such as walking in a shopping mall or a campus, having a conversation with more than two persons, and playing 3D video games, for as long as possible.</li>
		<li>Instruct the participant to keep a diary or provide a subjective report to an observer as frequently as possible about perceptual and behavioral changes, experienced events, and anything that the participant notices.</li>
		<li>After the target exposure period, instruct the participant to take off the reversed audition system. 
		NOTE: It is also important to follow up about the perceptual and behavioral changes in order to examine the recovery process from the adaption to left-right reversed audition.</li>
	</ol>
	</li>
	<li>Neuroimaging During the Exposure to Reversed Audition
	<ol>
		<li>Instruct the participant to train on a task that will be used during the neuroimaging experiments as sufficiently as possible.
		<ol>
			<li>For example, train the participant to perform a selective reaction time task in two conditions, compatible and incompatible15. The compatible condition consists of responding immediately to the right-ear sound with the right index finger and to the left-ear sound with the left index finger. The incompatible condition consists of responding immediately to the right-ear sound with the left index finger and to the left-ear sound with the right index finger.</li>
			<li>Use 1000-Hz sounds at 65-dB SPL for 0.1 s with an inter-stimulus interval of 2.5 &#8211; 3.5 s, which appears pseudorandomly on either ear side.</li>
		</ol>
		</li>
		<li>Before the exposure to reversed audition, conduct a neuroimaging experiment under the trained task.
		<ol>
			<li>For example, record either MEG or EEG responses, as well as the left and right finger responses under the selective reaction time task15. The task consists of two compatible and two incompatible blocks that are alternatively arranged with an inter-block interval of at least 30 s, and with sounds appearing 80 times for each block through the inserted earphones with plastic ear tubes. 
			NOTE: Although a 122-channel MEG system was used in Aoyama and Kuriki15, a multi-channel EEG system is also suitable for this protocol.</li>
			<li>For the MEG/EEG recording, set the sampling rate at 1 kHz and the analog recording passband at 0.03 &#8211; 200 Hz.</li>
		</ol>
		</li>
		<li>During approximately a 1-month exposure to reversed audition, conduct neuroimaging experiments under the trained task every week without the reversed audition system in exactly the same way as in the pre-exposure experiment (step 3.2.2). 
		NOTE: The system is removed immediately before and put on immediately after each experiment.</li>
		<li>One week after the exposure, conduct a neuroimaging experiment under the trained task in exactly the same way as the pre-exposure experiment (step 3.2.2).</li>
		<li>Analyze the collected data before, during, and after the exposure to left-right reversed audition.
		<ol>
			<li>For example, after rejecting the epochs contaminated with eye-related artifacts, removing the offset in the pre-stimulus interval, and setting the low-pass filtering at 40 Hz, average the MEG/EEG data from 100 ms before to 500 ms after the sound onset for the stimulus-response compatible and incompatible conditions15.</li>
			<li>Using an MNE software package19,20, estimate the sources of the brain activity with dynamic statistical parametric maps (dSPMs) overlaid on cortical surface images and quantify the intensities of brain activity with minimum-norm estimates (MNEs) for each time point of the averaged data.</li>
			<li>Calculate the auditory-motor functional connectivity from single-trial zero-mean MEG/EEG data from 90 to 500 ms after the sound onset for each condition 
			NOTE: Here we use&#160;MATLAB with the Multivariate Granger Causality Toolbox21.</li>
			<li>For the behavioral data, calculate the mean reaction times for the stimulus-response compatible and incompatible conditions.</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>

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The author has nothing to disclose.

The proposed protocol aimed to establish a methodology for studying adaptation to left-right reversed audition as an effective tool for uncovering the adaptability of humans to a novel auditory environment. As evidenced by the representative results, the constructed apparatus achieved left-right reversed audition with high spatiotemporal accuracy. Although the previous apparatuses for reversed audition11,12,13,<sup cl...

Adaptability to a novel environment is one of the fundamental functions for humans to live robustly in any situation. One effective tool for uncovering the mechanism of environmental adaptability in humans is an unusual sensory space that is artificially produced by apparatuses. In the majority of the previous studies dealing with this topic, special spectacles with prisms have been used to achieve left-right reversed vision1,2,3,4,5 or up-down reversed vision6,7. Furthermore, exposure to such vision from a few days to more than a month has revealed perceptual and behavioral adaptation1,2,3,4,5,6,7 (e.g., capability to ride a bicycle2,5,7). Moreover, periodic measurements of the brain activity using neuroimaging techniques, such as electroencephalography (EEG)1, magnetoencephalography (MEG)3, and functional magnetic resonance imaging (fMRI)2,4,5,7, have detected changes in the neural activity underlying the adaptation (e.g., bilateral visual activation for unilateral visual stimulation4,5). Although the participant&#39;s appearance becomes strange to some extent and great care is needed for the observer to maintain the participant&#39;s safety, reversed vision with prisms provides precise three-dimensional (3D) visual information without any delay in a wearable manner. Therefore, the methodology for uncovering the mechanism of environmental adaptability is relatively established in the visual domain.
In 1879, Thompson proposed a concept of pseudophone, &#34;an instrument for investigating the laws of binaural audition by means of the illusions it produces in the acoustic perception of space&#34;8. However, in contrast to the visual cases1,2,3,4,5,6,7, few attempts have been made to study the adaptation to unusual auditory spaces, and no noticeable knowledge has been obtained to date. Despite a long history of developing virtual auditory displays9,10, wearable apparatuses for controlling 3D audition have rarely been developed. Hence, only a few reports examined the adaptation to left-right reversed audition. One traditional apparatus consists of a pair of curved trumpets that are crossed and inserted into a participant&#39;s ear canals in a contrariwise manner11,12. In 1928, Young first reported the use of these crossed trumpets and wore them continuously for 3 days at most or a total of 85 h to test adaptation to left-right reversed audition. Willey et al.12 retested the adaptation in three participants wearing the trumpets for 3, 7, and 8 days, respectively. The curved trumpets easily provided left-right reversed audition, but had an issue with the reliability of spatial accuracy, wearability, and strange appearance. A more advanced apparatus for the reversed audition is an electronic system in which left and right lines of head/earphones and microphones are reversely connected13,14. Ohtsubo et al.13 achieved auditory reversal using the first ever binaural headphone-microphones that were connected to a fixed amplifier and evaluated its performance. More recently, Hofman et al.14 cross-linked complete-in-canal hearing aids and tested adaptation in two participants that wore the aids for 49 h in 3 days and 3 weeks, respectively. Although these studies have reported high performance of sound source localization in the front auditory field, the sound source localization in the backfield and a potential delay of electrical devices have never been evaluated. Especially in Hofman et al.&#39;s study, the spatial performance of the hearing aids was guaranteed for the front 60&#176; in the head-fixed condition and for the front 150&#176; in the head-free condition, suggesting unknown omniazimuth performance. Moreover, the exposure period may be too short to detect phenomena related to the adaptation as compared with the longer cases of reversed vision2,4,5. None of these studies have measured brain activity using neuroimaging techniques. Therefore, the uncertainty in spatiotemporal accuracy, the short exposure periods, and the non-utilization of neuroimaging could be reasons for the small number of reports and the limited amount of knowledge on adaptation to left-right reversed audition.
Thanks to the recent advances in wearable acoustic technology, Aoyama and Kuriki15 succeeded in constructing a left-right reversed 3D audition using only wearable devices that recently became available and achieved the omniazimuth system with high spatiotemporal accuracy. Moreover, approximately a 1-month exposure to reversed audition using the apparatus exhibited some representative results for MEG measurements. Based on this report, we describe, in this article, a detailed protocol to set-up, validate and use the system, and to test the adaptation to left-right reversed audition with the help of neuroimaging that is performed periodically without the system. This approach is effective for uncovering the adaptability of humans to a novel environment in the auditory domain.

<table><tbody><tr><td>Linear pulse-code-modulation recorder</td><td>Sony</td><td>PCM-M10</td><td></td></tr><tr><td>Binaural microphones</td><td>Roland</td><td>CS-10EM</td><td></td></tr><tr><td>Binaural in-ear earphones</td><td>Etymotic Research</td><td>ER-4B</td><td></td></tr><tr><td>Digital angle protractor</td><td>Wenzhou Sanhe Measuring Instrument</td><td>5422-200</td><td></td></tr><tr><td>Plane-wave speaker</td><td>Alphagreen</td><td>SS-2101</td><td></td></tr><tr><td>Video camera</td><td>Sony</td><td>HDR-CX560</td><td></td></tr><tr><td>MATLAB</td><td>Mathworks</td><td>R2012a, R2015a</td><td>R2012a for stimulation and R2015a for analysis</td></tr><tr><td>Psychophysics Toolbox</td><td>Free</td><td>Version 3</td><td>http://psychtoolbox.org</td></tr><tr><td>Insert earphones</td><td>Etymotic Research</td><td>ER-2</td><td></td></tr><tr><td>Magnetoencephalography system</td><td>Neuromag</td><td>Neuromag-122 TM</td><td></td></tr><tr><td>Electroencephalography system</td><td>Brain Products</td><td>acti64CHamp</td><td></td></tr><tr><td>MNE</td><td>Free</td><td>MNE Software Version 2.7,&lt;br/&gt; MNE 0.13</td><td>https://martinos.org/mne/stable/index.html</td></tr><tr><td>The Multivariate Granger Causality Toolbox</td><td>Free</td><td>mvgc_v1.0</td><td>http://www.sussex.ac.uk/sackler/mvgc/</td></tr></tbody></table>

a method to study adaptation to left-right reversed audition

An unusual sensory space is one of the effective tools to uncover the mechanism of adaptability of humans to a novel environment. Although most of the previous studies have used special spectacles with prisms to achieve unusual spaces in the visual domain, a methodology for studying the adaptation to unusual auditory spaces has yet to be fully established. This study proposes a new protocol to set-up, validate, and use a left-right reversed stereophonic system using only wearable devices, and to study the adaptation to left-right reversed audition with the help of neuroimaging. Although individual acoustic characteristics are not yet implemented, and slight spillover of unreversed sounds is relatively uncontrollable, the constructed apparatus shows high performance in a 360&#176; sound source localization coupled with hearing characteristics with little delay. Moreover, it looks like a mobile music player and enables a participant to focus on daily life without arousing curiosity or drawing attention of other individuals. Since the effects of adaptation were successfully detected at the perceptual, behavioral, and neural levels, it is concluded that this protocol provides a promising methodology for studying adaptation to left-right reversed audition, and is an effective tool for uncovering the adaptability of humans to a novel environments in the auditory domain.

The representative results shown here are based on Aoyama and Kuriki15. The present protocol achieved left-right reversed audition with high spatiotemporal accuracy. Figure 1 shows the sound source localization in directions over 360&#176; before and immediately after putting on the left-right reversed audition system (Figure 1A), in six participants, as indicated by the cosine similarity. As shown in <str...

Watch this Scientific Journal Video about A Method to Study Adaptation to Left-Right Reversed Audition at JoVE.com

A Method to Study Adaptation to Left-Right Reversed Audition

The present study proposes a protocol to investigate the adaptation to left-right reversed audition achieved only by wearable devices, using neuroimaging, which can be an effective tool for uncovering the adaptability of humans to a novel environment in the auditory domain.

An unusual sensory space is one of the effective tools to uncover the mechanism of adaptability of humans to a novel environment. Although most of the ...

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Research

JoVE Journal

Behavior

6.4K Views.  Keio University. The present study proposes a protocol to investigate the adaptation to left-right reversed audition achieved only by wearable devices, using neuroimaging, which can be an effective tool for uncovering the adaptability of humans to a novel environment in the auditory domain.

Video: A Method to Study Adaptation to Left-Right Reversed Audition

Behavioral Determination of Stimulus Pair Discrimination of Auditory Acoustic and Electrical Stimuli Using a Classical Conditioning and Heart-rate Approach

Acute animal preparations have been used in research prospectively investigating electrode designs and stimulation techniques for integration into neural auditory prostheses, such as auditory brainstem implants1-3 and auditory midbrain implants4,5. While acute experiments can give initial insight to the effectiveness of the implant, testing the chronically implanted and awake animals provides the advantage of examining the psychophysical properties of the sensations induced using implanted devices6,7.
Several techniques such as reward-based operant conditioning6-8, conditioned avoidance9-11, or classical fear conditioning12 have been used to provide behavioral confirmation of detection of a relevant stimulus attribute. Selection of a technique involves balancing aspects including time efficiency (often poor in reward-based approaches), the ability to test a plurality of stimulus attributes simultaneously (limited in conditioned avoidance), and measure reliability of repeated stimuli (a potential constraint when physiological measures are employed).
Here, a classical fear conditioning behavioral method is presented which may be used to simultaneously test both detection of a stimulus, and discrimination between two stimuli. Heart-rate is used as a measure of fear response, which reduces or eliminates the requirement for time-consuming video coding for freeze behaviour or other such measures (although such measures could be included to provide convergent evidence). Animals were conditioned using these techniques in three 2-hour conditioning sessions, each providing 48 stimulus trials. Subsequent 48-trial testing sessions were then used to test for detection of each stimulus in presented pairs, and test discrimination between the member stimuli of each pair. 
This behavioral method is presented in the context of its utilisation in auditory prosthetic research. The implantation of electrocardiogram telemetry devices is shown. Subsequent implantation of brain electrodes into the Cochlear Nucleus, guided by the monitoring of neural responses to acoustic stimuli, and the fixation of the electrode into place for chronic use is likewise shown.

The application of a classical fear conditioning behavioral paradigm for auditory prosthetic research in rats is described. This paradigm provides a mechanism for identifying both detection of, and discrimination between, distinct acoustic and electrical stimuli using heart-rate as an outcome measure.

Acute animal preparations have been used in research prospectively investigating electrode designs and stimulation techniques for integration into neural ...

Neuroscience

A Two-interval Forced-choice Task for Multisensory Comparisons

We provide a procedure for a psychophysics experiment in humans based on a previously described paradigm aimed to characterize the perceptual duration of intervals within the range of milliseconds of visual, acoustic, and audiovisual aperiodic trains of six pulses. In this task, each of the trials consists of two consecutive intramodal intervals where the participants press the upward arrow key to report that the second stimulus lasted longer than the reference, or the downward arrow key to indicate otherwise. The analysis of the behavior results in psychometric functions of the probability of estimating the comparison stimulus to be longer than the reference, as a function of the comparison intervals. In conclusion, we advance a way of implementing standard programming software to create visual, acoustic, and audiovisual stimuli, and to generate a two-interval forced-choice (2IFC) task by delivering stimuli through noise-blocking headphones and a computer&#39;s monitor.

Psychophysics is essential for studying perception phenomena through sensory information. Here we present a protocol to perform a two-interval forced-choice task as implemented in a previous report on human psychophysics where participants estimated the duration of visual, auditory, or audiovisual intervals of aperiodic trains of pulses.

We provide a procedure for a psychophysics experiment in humans based on a previously described paradigm aimed to characterize the perceptual duration of ...

A Low Cost Setup for Behavioral Audiometry in Rodents

In auditory animal research it is crucial to have precise information about basic hearing parameters of the animal subjects that are involved in the experiments. Such parameters may be physiological response characteristics of the auditory pathway, e.g. via brainstem audiometry (BERA). But these methods allow only indirect and uncertain extrapolations about the auditory percept that corresponds to these physiological parameters. To assess the perceptual level of hearing, behavioral methods have to be used. A potential problem with the use of behavioral methods for the description of perception in animal models is the fact that most of these methods involve some kind of learning paradigm before the subjects can be behaviorally tested, e.g. animals may have to learn to press a lever in response to a sound. As these learning paradigms change perception itself 1,2 they consequently will influence any result about perception obtained with these methods and therefore have to be interpreted with caution. Exceptions are paradigms that make use of reflex responses, because here no learning paradigms have to be carried out prior to perceptual testing. One such reflex response is the acoustic startle response (ASR) that can highly reproducibly be elicited with unexpected loud sounds in na&iuml;ve animals. This ASR in turn can be influenced by preceding sounds depending on the perceptibility of this preceding stimulus: Sounds well above hearing threshold will completely inhibit the amplitude of the ASR; sounds close to threshold will only slightly inhibit the ASR. This phenomenon is called pre-pulse inhibition (PPI) 3,4, and the amount of PPI on the ASR gradually depends on the perceptibility of the pre-pulse. PPI of the ASR is therefore well suited to determine behavioral audiograms in na&iuml;ve, non-trained animals, to determine hearing impairments or even to detect possible subjective tinnitus percepts in these animals. In this paper we demonstrate the use of this method in a rodent model (cf. also ref. 5), the Mongolian gerbil (Meriones unguiculatus), which is a well know model species for startle response research within the normal human hearing range (e.g. 6).

A fast and inexpensive method for the behavioral determination of hearing parameters like hearing thresholds, hearing impairments or phantom perceptions (subjective tinnitus) is described. It uses pre-pulse inhibition of the acoustic startle response and can be easily implemented in a personal computer using a programmable AD/DA-converter and a piezo sensor.

In auditory animal research it is crucial to have precise information about basic hearing parameters of the animal subjects that are involved in the ...

A Lightweight, Headphones-based System for Manipulating Auditory Feedback in Songbirds

Experimental manipulations of sensory feedback during complex behavior have provided valuable insights into the computations underlying motor control and sensorimotor plasticity1. Consistent sensory perturbations result in compensatory changes in motor output, reflecting changes in feedforward motor control that reduce the experienced feedback error. By quantifying how different sensory feedback errors affect human behavior, prior studies have explored how visual signals are used to recalibrate arm movements2,3 and auditory feedback is used to modify speech production4-7. The strength of this approach rests on the ability to mimic naturalistic errors in behavior, allowing the experimenter to observe how experienced errors in production are used to recalibrate motor output.
Songbirds provide an excellent animal model for investigating the neural basis of sensorimotor control and plasticity8,9. The songbird brain provides a well-defined circuit in which the areas necessary for song learning are spatially separated from those required for song production, and neural recording and lesion studies have made significant advances in understanding how different brain areas contribute to vocal behavior9-12. However, the lack of a naturalistic error-correction paradigm - in which a known acoustic parameter is perturbed by the experimenter and then corrected by the songbird - has made it difficult to understand the computations underlying vocal learning or how different elements of the neural circuit contribute to the correction of vocal errors13.
The technique described here gives the experimenter precise control over auditory feedback errors in singing birds, allowing the introduction of arbitrary sensory errors that can be used to drive vocal learning. Online sound-processing equipment is used to introduce a known perturbation to the acoustics of song, and a miniaturized headphones apparatus is used to replace a songbird's natural auditory feedback with the perturbed signal in real time. We have used this paradigm to perturb the fundamental frequency (pitch) of auditory feedback in adult songbirds, providing the first demonstration that adult birds maintain vocal performance using error correction14. The present protocol can be used to implement a wide range of sensory feedback perturbations (including but not limited to pitch shifts) to investigate the computational and neurophysiological basis of vocal learning.

We describe the design and assembly of miniaturized headphones suitable for replacing a songbird&#x2019;s natural auditory feedback with a manipulated acoustic signal. Online sound processing hardware is used to manipulate song output, introduce real-time errors in auditory feedback via the headphones, and drive vocal motor learning.

Experimental manipulations of sensory feedback during complex behavior have provided valuable insights into the computations underlying motor control and ...

Sound Source Localization Testing in Single-sided Deafness Following Bone Conduction Intervention

Single-sided deafness (SSD), where there is severe to profound hearing loss in one ear and normal hearing in the other, is a prevalent auditory condition that significantly impacts the quality of life for those affected. The ability to accurately localize sound sources is crucial for various everyday activities, including speech communication and environmental awareness. In recent years, bone conduction intervention has emerged as a promising solution for patients with SSD, offering a non-invasive alternative to traditional air conduction hearing aids. However, the effectiveness of bone conduction devices (BCDs), especially in terms of improving sound localization abilities, remains a topic of considerable interest.
Here, we present a protocol to assess the impact of bone conduction intervention on sound localization ability in patients with SSD. The protocol includes the experimental setup (a sound-treated room and a semicircular array of loudspeakers), stimuli, and data analysis methods. Participants indicate the perceived direction of noise bursts, and their responses are analyzed using root mean square error (RMSE) and bias. The results of sound localization testing before and after bone conduction intervention are reported and compared. Despite no significant differences, most patients (71%) had a localization bias clearly toward the intervention side after bone conduction intervention. The study concludes that bone conduction intervention can promptly enhance certain sound localization skills in patients with SSD, offering evidence to support the efficacy of BCDs as a treatment for SSD.

We present a protocol to evaluate the impact of bone conduction intervention on sound localization ability in patients with single-sided deafness (SSD). This protocol can be applied to assess the efficacy of bone conduction devices in restoring sound localization abilities and improving the overall quality of life for individuals with SSD.

Single-sided deafness (SSD), where there is severe to profound hearing loss in one ear and normal hearing in the other, is a prevalent auditory condition ...

Data Acquisition and Analysis In Brainstem Evoked Response Audiometry In Mice

Brainstem evoked response audiometry (BERA) is of central relevance in the clinical neurophysiology. As other evoked potential (EP) techniques, such as visually evoked potentials (VEPs) or somatosensory evoked potentials (SEPs), the auditory evoked potentials (AEPs) are triggered by the repetitive presentation of identical stimuli, the electroencephalographic (EEG) response of which is subsequently averaged resulting in distinct positive (p) and negative (n) deflections. In humans, both the amplitude and the latency of individual peaks can be used to characterize alterations in synchronization and conduction velocity in the underlying neuronal circuitries. Importantly, AEPs are also applied in basic and preclinical science to identify and characterize the auditory function in pharmacological and genetic animal models. Even more, animal models in combination with pharmacological testing are utilized to investigate for potential benefits in the treatment of sensorineural hearing loss (e.g., age- or noise-induced hearing deficits). Here we provide a detailed and integrative description of how to record auditory brainstem-evoked responses (ABRs) in mice using click and tone-burst application. A specific focus of this protocol is on pre-experimental animal housing, anesthesia, ABR recording, ABR filtering processes, automated wavelet-based amplitude growth function analysis, and latency detection.

Brainstem evoked response audiometry is an important tool in clinical neurophysiology. Nowadays, brainstem evoked response audiometry is also applied in the basic science and preclinical studies involving both pharmacological and genetic animal models. Here we provide a detailed description of how auditory brainstem responses can be successfully recorded and analyzed in mice.

Brainstem evoked response audiometry (BERA) is of central relevance in the clinical neurophysiology. As other evoked potential (EP) techniques, such as ...

Measuring Electrically Evoked Stapedius Reflex for Cochlear Implant Fitting

Electrically Evoked Stapedius Reflex Measurements in Cochlear Implantation and Its Application in the Postoperative Fitting Process

Measuring the electrically evoked stapedius reflex during the fitting of cochlear implants (CIs) provides a reliable estimation of maximum comfort levels, resulting in the programming of the CI with high hearing comfort and good speech understanding. Detection of the stapedius reflex and the required stimulation level on each implant channel is already being performed during surgery, whereby intraoperative stapedius reflexes are observed through the surgical microscope. Intraoperative stapedius reflex detection is both an indicator that the auditory nerve is responding to electrical stimulation up to the brainstem and a test for the ability to perform postoperative stapedius reflex measurements. Postoperative stapedius reflex thresholds can be used to estimate upper stimulation levels in the CI fitting process. In particular, in children or patients unable to provide feedback on loudness perception, this method avoids inadequate stimulation with the CI, which can result in poor hearing performance. In addition, overstimulation can be avoided, which could even lead to refusal to use the device.

The present protocol describes the measurement of the electrically evoked stapedius reflex (eSR) via cochlear implant (CI). Two applications are discussed: intraoperative detection of eSR for verification of the coupling between the cochlear implant and the auditory nerve and postoperative measurement of eSR thresholds (eSRT) for CI fitting.

Measuring the electrically evoked stapedius reflex during the fitting of cochlear implants (CIs) provides a reliable estimation of maximum comfort levels, ...

Medicine

Dichotic Listening

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

It is a well-known fact that the human ability to process incoming stimuli is limited. Nonetheless, the world is complicated, and there are always many things going on at once. Selective attention is the mechanism that allows humans and other animals to control which stimuli get processed and which become ignored. Think of a cocktail party: a person couldn&#8217;t possibly attend to all of the conversations taking place at once. However, everyone has the ability to selectively listen to one conversation, leading all the rest to become unattended to and nothing more than background noise. In order to study how people do this, researchers simulate a more controlled cocktail party environment by playing sounds to participants dichotically, i.e., by playing different sounds simultaneously to each ear. This is called a dichotic listening paradigm.
This experiment demonstrates standard procedures for investigating selective auditory attention with a paradigm called dichotic listening.

Dichotic Listening: Investigating Selective Auditory Attention

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

It is a well-known fact that the human ability to process incoming stimuli is ...

Education

JoVE Science Education

Psychology

Cognitive Psychology

Measuring the Auditory Brainstem Response in Mice

<a href='https://app.jove.com/v/64286/modified-experimental-conditions-for-noise-induced-hearing-loss-mice'>Source: Lee, D., et. al. Modified Experimental Conditions for Noise-Induced Hearing Loss in Mice and Assessment of Hearing Function and Outer Hair Cell Damage. J. Vis. Exp. (2023)</a>This video demonstrates the measurement of auditory brainstem response (ABR) in a mouse. Electrodes are placed on the head, behind the ear, and near the tail of an anesthetized mouse. Acoustic stimuli at various intensities are delivered, and electric signals generated are recorded as waveforms.

Source: Lee, D., et. al. Modified Experimental Conditions for Noise-Induced Hearing Loss in Mice and Assessment of Hearing Function and Outer Hair Cell ...

JoVE Encyclopedia of Experiments

Neuropathology

Neuromuscular Disorders

Recording Auditory Brainstem Responses in a Rat Pup

Source: Chang, A. et al., <a href="https://app.jove.com/v/56678">Auditory Brainstem Response and Outer Hair Cell Whole-cell Patch Clamp Recording in Postnatal Rats.</a> J. Vis. Exp. (2018).
This video demonstrates a method for recording auditory brainstem responses (ABRs) from rat pups. It outlines the steps for electrode placement, sound stimulus application, and signal processing analysis in the brainstem to assess neural responses.

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.
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