Encoding Temporal Fine Structure for Cochlear Implants

Hearing Loss Clinical Trial

— TFS4CIs  

Official title:

Encoding Temporal Fine Structure for Cochlear Implants

Clinical Trial Details — Status: Recruiting

Administrative data

• NCT number: NCT04708717
• Other study ID #: R01DC018044
• Status: Recruiting
• Phase: N/A
• Start date: September 1, 2020
• Est. completion date: December 5, 2024

Study information

• Verified date: November 2023
• Source: University of Southern California
• Contact: Ray Goldsworthy, PhD
• Phone: 2132223384
• Email: raymond.goldsworthy[@]med.usc.edu
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

The goal of this study is to improve music and speech perception for cochlear implant users. Presently, most cochlear implants discard the temporal fine structure of sound, which is information that is widely believed to contribute to both music and speech perception. The proposed work examines perceptual and physiological changes that occur once this information is provided to cochlear implant users in a clear and consistent manner.

Description:

The study goal is to improve music and speech perception for cochlear implant users. The relevant health outcome is their quality of life. This proposal focuses on how well cochlear implant users can learn to use temporal fine structure if provided as a clear and consistent cue for music or voice pitch. Historically, cochlear implants have discarded temporal fine structure and have only transmitted timing information of relatively slow envelope fluctuations. Attempts have been made to restore temporal fine structure into cochlear implant stimulation, but it is unclear whether previous attempts were limited by implementation, lack of experience, or inherently by physiology. The proposed approach is unique in that it examines the perceptual and physiological plasticity that occurs when temporal fine structure is restored. Proposed research is organized into two aims, which examine the relative salience of stimulation place and rate for providing a sense of pitch (Aim 1) and the salience of dynamic-rate stimulation compared to conventional methods (Aim 2). Both aims combine perceptual learning, computer-controlled electrode psychophysics, electrophysiology, and computational neural modeling to characterize the plasticity of pitch perception in cochlear implant users.

Aim 1 examines the perceptual and physiological plasticity associated with place and rate of cochlear implant stimulation. Cochlear implant users hear an increasing pitch associated with increasing stimulation rate, but this effect is difficult to measure above 300 Hz. Most studies of psychophysical sensitivity to cochlear implant stimulation rate have not considered perceptual learning. Preliminary results show that the sense of pitch provided by stimulation rate improves with training. The proposed research examines perceptual sensitivity and physiological encoding throughout a crossover training study with training provided for pitch based on place and rate of stimulation. The primary hypothesis tested is that cochlear implant users have a latent ability to hear pitch associated with stimulation rate, but they require training to learn how to use this new information.

Aim 2 is to determine whether dynamic-rate stimulation provides better sensitivity and better physiological encoding of fundamental frequency compared to conventional stimulation methods based on amplitude modulation of constant-rate stimulation. In normal physiology, auditory-nerve activity phase locks to the temporal fine structure of sound. Since cochlear implants typically discard this information, it is unknown how well cochlear implant users can learn to use it if provided. Aim 2 focuses on the comparison between dynamic-rate stimulation in which stimulation rate is dynamically adjusted to convey temporal fine structure compared to conventional methods based on amplitude modulation of constant-rate stimulation. The primary hypothesis is that dynamic-rate stimulation provides better pitch sensitivity and better physiological encoding compared to amplitude modulation of constant-rate stimulation.

Recruitment information / eligibility

• Status: Recruiting
• Enrollment: 24
• Est. completion date: December 5, 2024
• Est. primary completion date: September 1, 2024
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: All
• Age group: 18 Years and older

Eligibility

Inclusion Criteria:

• Cochlear implant users.

Exclusion Criteria:

• Younger than 18 years.

Related Conditions & MeSH terms

• Cochlear Implants
• Hearing Loss

Intervention

Behavioral:
• Stimulation Rate
Psychophysical training listening to stimulation rate as a cue for auditory pitch perception. The intervention is the listening rehabilitative exercises. Exercises are completed daily as 30-minute sessions for 2 weeks.
• Electrode Location
Psychophysical training listening to electrode location as a cue for auditory pitch perception. The intervention is the listening rehabilitative exercises. Exercises are completed daily as 30-minute sessions for 2 weeks.

Locations

Country	Name	City	State
United States	University of Southern California	Los Angeles	California

Sponsors (3)

Lead Sponsor	Collaborator
University of Southern California	Ohio State University, University of Rochester

Country where clinical trial is conducted

United States, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Baseline electrode psychophysics prior to training.	Just-noticeable difference for pitch ranking based on stimulation cues. Pitch discrimination will be measured as provided independently by place and rate of cochlear implant stimulation, as well as in combination. Stimuli will be dual-electrode pulse trains, which probe place-pitch perception with greater resolution than possible with single-electrode stimulation. Two-alternative forced-choice procedures will be used in which participants judge which of two stimuli is higher in pitch. Frequency discrimination will be measured near condition frequencies of 110, 220, 440, 880, and 1760 Hz for each of the 4 stimulation conditions (place, rate, combined). Adaptive procedures will be used to measure 75% discrimination accuracy.	Measure collected prior to training.
Primary	Midpoint electrode psychophysics.	Just-noticeable difference for pitch ranking based on stimulation cues. Pitch discrimination will be measured as provided independently by place and rate of cochlear implant stimulation, as well as in combination. Stimuli will be dual-electrode pulse trains, which probe place-pitch perception with greater resolution than possible with single-electrode stimulation. Two-alternative forced-choice procedures will be used in which participants judge which of two stimuli is higher in pitch. Frequency discrimination will be measured near condition frequencies of 110, 220, 440, 880, and 1760 Hz for each of the 4 stimulation conditions (place, rate, combined). Adaptive procedures will be used to measure 75% discrimination accuracy.	Measure collected at 4-week midpoint during psychophysical training.
Primary	Endpoint electrode psychophysics.	Just-noticeable difference for pitch ranking based on stimulation cues. Pitch discrimination will be measured as provided independently by place and rate of cochlear implant stimulation, as well as in combination. Stimuli will be dual-electrode pulse trains, which probe place-pitch perception with greater resolution than possible with single-electrode stimulation. Two-alternative forced-choice procedures will be used in which participants judge which of two stimuli is higher in pitch. Frequency discrimination will be measured near condition frequencies of 110, 220, 440, 880, and 1760 Hz for each of the 4 stimulation conditions (place, rate, combined). Adaptive procedures will be used to measure 75% discrimination accuracy.	Measure collected at 8-week endpoint following psychophysical training.