Interaural Frequency and Loudness Mismatch in SSD CI Users

Effects of Interaural Frequency and Loudness Mismatch on SSD-CI Performance

Interaural loudness and pitch mismatch in single-sided deaf cochlear implant (SSD-CI) recipients reduces binaural processing cues and contributes to performance outcomes, specifically speech understanding in noise and localization. The study aims to improve binaural cues through speech processor program modifications that reduce interaural mismatches.

Study Overview

• Status: Completed
• Conditions: Outcomes
• Intervention / Treatment: Device: Treatment-modifications to CI speech processor program. Specifically reducing interaural frequency mismatch in experienced SSD-CI recipients.; Device: Treatment-modifications to CI speech processor program to reduced interaural frequency mismatch in newly implanted SSD-CI recipients.; Device: Treatment-modifications to CI speech processor program to reduced interaural loudness mismatch in experienced SSD-CI recipients.

Detailed Description

Effective binaural processing depends on similar loudness growth functions at each ear. The use of interaural level differences (ILDs), perceived as loudness differences, to locate sound is critical given the inability of cochlear implant (CI) recipients to use interaural time differences (ITDs) in binaural processing. In CI recipients with single-sided deafness (SSD), perceived interaural loudness differences may not be valid indicators of interaural level differences because the CI compresses amplitude. Studies suggest better preservation of ILDs may contribute to improved localization and understanding in noise. Since SSD-CI recipients use only one device, an approach to improve their use of ILDs is to match perceived loudness at each ear.

Binaural processing is also affected when signals of equal frequency are not matched in pitch at each ear. In bilateral CI recipients, the investigators found that the greater the pitch mismatch between ears, the poorer the speech understanding in noise. The investigators want to extend this work to SSD-CI recipients. Through CI program modifications, the study aims to decrease the pitch and loudness mismatch between the CI ear and the normal hearing ear to improve binaural listening abilities, specifically speech understanding in noise and sound localization.

• Study Type: Interventional
• Enrollment (Actual): 45
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Missouri
    • St Louis, Missouri, United States, 63110
      • Washington University School of Medicine

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Participants for the proposed study will be adults with single-sided deafness. Participants will have at least 6 months experience with their cochlear implant or will be newly implanted with the cochlear implant.

Inclusion criteria for the experienced CI user group and the newly implant group are as follows:

• 18 years of age and older
• Postlingual onset of SSD
• Pure tone average (PTA) at 500, 1000, and 2000 Hz of less than or equal to 30 dB HL in the contralateral ear, known as the normal hearing ear
• Implanted with or chosen to be implanted with a Nucleus cochlear implant
• Full insertion of electrode array

Exclusion Criteria:

• • Not meeting the inclusion criteria

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Non-Randomized
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Period 1: Study 1; CI speech processor programming in experienced cochlear implant (CI) recipients with single sided deafness. Program changes were made to decrease the interaural frequency mismatch between the CI ear and the contralateral ear.	Device: Treatment-modifications to CI speech processor program. Specifically reducing interaural frequency mismatch in experienced SSD-CI recipients.; We will modify the CI speech processor program to reduce interaural frequency mismatch between the CI ear and the contralateral ear in experienced CI recipients with SSD.
Experimental: Period 2: Study 2; CI speech processor programming in newly implanted cochlear implant (CI) recipients with single sided deafness. Program changes were made to decrease the interaural frequency mismatch between the CI ear and the contralateral ear.	Device: Treatment-modifications to CI speech processor program to reduced interaural frequency mismatch in newly implanted SSD-CI recipients.; We will modify the CI speech processor program to reduce interaural frequency mismatch between the CI ear and the contralateral ear in newly implanted CI recipients with SSD.
Experimental: Period 3: study 3; CI speech processor programming in experienced cochlear implant (CI) recipients with single sided deafness. Program changes were made to decrease the interaural loudness mismatch between the CI ear and the contralateral ear.	Device: Treatment-modifications to CI speech processor program to reduced interaural loudness mismatch in experienced SSD-CI recipients.; We will modify the CI speech processor program to reduce interaural loudness mismatch between the CI ear and the contralateral ear in experienced CI recipients with SSD.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Speech Understanding in Noise, Measured With the R-Space Test Environment. The R-Space Test Environment Simulates Speech Understanding in a Noisy Restaurant.	Participants speech understanding was evaluated in the R-Space test environment with two speech processor programs, an everyday or default program and a modified program. The modified program was created to reduce interaural frequency or loudness mismatch between participants' CI ear and normal hearing ear. The R-Space simulates listening in a noisy restaurant, a real-world listening situation. The score is a signal-to-noise ratio that reflects 50% speech understanding in noise. Participants are surrounded by 8 loudspeakers with restaurant noise from all 8. A sentence is presented from the front loudspeaker. Participants repeat back what they hear. The noise is adjusted adaptively. For a correct response, the noise is increased; it is decreased for an incorrect response. This provides signal-to-noise ratio (SNR) for 50% speech understanding. The average score for participants with normal hearing is -5 dB SNR. A lower number represents better performance than a higher number.	Participants were tested in the R-Space twice with each speech processor program, e.g., everyday or default program and modified program. The testing was carried out within a 2-3 month time period, and after using each program for at least 6 weeks.

Collaborators and Investigators

• Sponsor: Washington University School of Medicine
• Collaborators: Cochlear
• Investigators: Principal Investigator: Jill B Firszt, PhD, Washington University School of Medicine

Study record dates

Study Major Dates

• Study Start (Actual): August 12, 2022
• Primary Completion (Actual): July 30, 2024
• Study Completion (Actual): August 1, 2025

Study Registration Dates

• First Submitted: August 8, 2022
• First Submitted That Met QC Criteria: August 8, 2022
• First Posted (Actual): August 10, 2022

Study Record Updates

• Last Update Posted (Actual): March 23, 2026
• Last Update Submitted That Met QC Criteria: March 9, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Anti-Infective Agents; Anti-Infective Agents, Local; Silver Sulfadiazine
• Other Study ID Numbers: 202206085

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: No