Cochlear Implantation in Cases of Single-Sided Deafness

Study Overview
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Brief Summary
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The primary goal of this project is to determine whether subjects with Single-Sided Deafness (SSD) experience an improvement in speech perception, localization, and quality of life with a cochlear implant as compared to an unaided listening condition.

Detailed Description
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Single-sided deafness (SSD) can be defined as moderate-to-profound sensorineural hearing loss with limited speech perception benefit in one ear and normal hearing in the contralateral ear. Though one ear is within the normal hearing limits, SSD may result in reduced speech perception in noise, variable abilities on localization tasks, increased subjective report of hearing handicap, and reduced quality of life. This patient population cannot utilize conventional amplification due to the severity of the hearing loss and poor speech discrimination abilities in the affected ear. Current treatment options include: contralateral routing of the signal (CROS) hearing aids, and bone-conduction devices. A CROS hearing aid is a two-part system that includes a microphone/transmitter on the affected ear and a receiver on the normal hearing ear. The microphone/transmitter sends the acoustic signal from the affected ear to the receiver, which is presented to the normal hearing ear. Bone-conduction devices utilize a percutaneous, implanted titanium abutment to send the acoustic signal from the affected side to the normal hearing ear via vibrations. The goal of both of these technologies is to send the signal from the affected side to the normal hearing side, thereby leaving the patient in a unilateral listening condition. Though CROS hearing aids and bone-conduction devices provide the patient with auditory information from both sides to the better hearing ear, the ability to use binaural cues for speech perception in noise is variable. It is of interest whether cochlear implantation of the affected ear would benefit the SSD population. A cochlear implant is a two-part system, including the internal electrode array and external speech processor. The internal electrode array is surgically implanted into the affected cochlea. The external speech processor receives sounds and transmits this signal to the internal portion. The electrode array presents the acoustic signal via electrical pulses within the cochlea, which is interpreted by the brain as sound. Presumably, cochlear implantation may provide the SSD population improvements in speech perception in the affected ear, which cannot benefit from appropriately fit hearing aids. Cochlear implantation may provide a benefit over current treatment options in the SSD population, as it stimulates the auditory pathway on the affected side, thus allowing for ipsilateral representation of acoustic signals arriving to each ear independently. The primary goal of this project is to determine whether subjects with SSD experience an improvement in speech perception, localization, and quality of life with a cochlear implant as compared to an unaided listening condition. Secondary aims include: 1) a comparison of speech perception, localization, and quality of life outcomes in the study population to a SSD control group with long-term listening experience with a current treatment option (i.e. bone-conduction device), and 2) a within-subject comparison of speech perception and localization abilities with cochlear implantation versus the bone-conduction test device.

Official Title
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Cochlear Implantation in Cases of Single-Sided Deafness

Conditions
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Unilateral Moderate to Profound Hearing Loss, Asymmetric Hearing Loss, Single-Sided Deafness (SSD)

Intervention / Treatment
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* Device: Cochlear Implant
* Other: Control Group


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria (SSD): Unilateral moderate-to-profound sensorineural hearing loss [Unaided residual hearing thresholds measured from 250-8000 Hertz (Hz) (Pure Tone Average (PTA) ≥70 decibel (dB) Hearing Level (HL) in the ear to be implanted] Normal to mild residual hearing thresholds from 250-8000 Hz in the contralateral ear (≤35 dB HL at each frequency, 250-8000 Hz) Greater than or equal to 18 years of age at implantation Duration of moderate-to-profound sensorineural hearing loss less than or equal to 5 years [Either reported by subject or documented in previous audiograms] [Can be less than or equal to 10 years if the subject consistently utilized hearing technology (such as a bone conduction device or conventional hearing aid) within the past 5 years] Previous experience with a current treatment option for SSD, including a conventional hearing aid, bone-conduction device, or CROS/BICROS (Bilateral Contralateral Routing Of the Signal) technology. [At least one month of listening experience with device] [Dissatisfaction with and/or discontinued use of current treatment option due to: insufficient gain, poor sound quality, and/or lack of perceived benefit] Aided word recognition in the ear to be implanted of 60% or less as measured with Consonant-Nucleus-Consonant (CNC) words (50-word list) [When listening with an appropriately fit hearing aid and masking applied to the contralateral ear] [Aided testing will be conducted in a sound-proof booth with the subject seated 1 meter from the sound source, facing 0° azimuth. Recorded materials will be presented at 60 dB Sound Pressure Level (SPL).] [The hearing aid output will be measured using National Acoustic Laboratory-NonLinear (NAL-NL1) targets.] Realistic expectations Willing to obtain recommended meningitis vaccinations per Center for Disease Control (CDC) recommendations No reported cognitive issues [Pass the Mini Mental State Examination (MMSE) screener] Able and willing to comply with study requirements, including travel to investigational site and study-related activities Exclusion Criteria (SSD): Non-native English speaker [Speech perception materials are presented in English] Conductive hearing loss in either ear Compromised auditory nerve, including those with a history of vestibular schwannoma Ossification Inability to participate in follow-up procedures (i.e., unwillingness, geographic location) History of meningitis, autoimmune disease, or any medical condition that contraindicate middle or inner ear surgery or anesthesia Meniere's disease with intractable vertigo Trauma that precludes inner ear surgery Case of sudden sensorineural hearing loss that has not been first evaluated by a physician Pregnancy [Subjects who are pregnant or become pregnant prior to surgery are excluded due to the potential risk of anesthesia to an unborn child.] [Subjects who become pregnant after surgery may continue to participate in study procedures] Tinnitus as the primary purpose for seeking cochlear implantation Subject obtains a severe or catastrophic score on the Tinnitus Handicap Inventory (Newman, Jacobson & Spitzer, 1996). Inclusion Criteria (asymmetric hearing loss): a. Ear to be implanted i. Moderate-to-profound sensorineural hearing loss ii. PTA ≥70 dB HL iii. Aided word recognition of 60% or less as measured with CNC words (50-word list). b. Contralateral ear i. PTA ≥35 and ≤55 dB HL ii. Aided word recognition of 80% or more as measured with CNC words (50-word list). iii. Use of conventional amplification c. Greater than or equal to 18 years of age at implantation d. Duration of moderate-to-profound sensorineural hearing loss in the ear to be implanted is less than or equal to 5 years [Either reported by subject or documented in previous audiograms. Can be up to 10 years if the subject consistently utilized hearing technology in the ear to be implanted (such as a bone conduction device or conventional hearing aid) within the past 5 years] e. Previous experience with a current treatment option for asymmetric hearing loss, including a conventional hearing aid, bone-conduction device, or CROS/BiCROS technology. [At least one month of listening experience with device. Dissatisfaction with and/or discontinued use of current treatment option due to: insufficient gain, poor sound quality, and/or lack of perceived benefit.] f. Realistic expectations g. Willing to obtain recommended meningitis vaccinations per CDC recommendations h. No reported cognitive issues [Pass the Mini Mental State Examination (MMSE) screener] i. Able and willing to comply with study requirements, including travel to investigational site and study-related activities Exclusion Criteria (Asymmetric hearing loss): Non-English speaker [Speech perception materials are presented in English] Medical condition considered a contraindication to undergoing cochlear implantation Conductive hearing loss in either ear Compromised auditory nerve, including those with a history of vestibular schwannoma Ossification Inability to participate in follow-up procedures (i.e., unwillingness, geographic location) History of meningitis, autoimmune disease, or any medical condition that contraindicate middle or inner ear surgery or anesthesia Meniere's disease with intractable vertigo Trauma that precludes inner ear surgery Case of sudden sensorineural hearing loss that has not been first evaluated by a physician Pregnancy [Subjects who are pregnant or become pregnant prior to surgery are excluded due to the potential risk of anesthesia to an unborn child. Subjects who become pregnant after surgery may continue to participate in study procedures] Tinnitus as the primary purpose for seeking cochlear implantation Subject obtains a severe or catastrophic score on the Tinnitus Handicap Inventory (Newman, Jacobson & Spitzer, 1996).

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

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


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Cochlear Implant<br>Cochlear implantation of the affected ear | Device: Cochlear Implant<br>* cochlear implantation used a treatment for single-sided deafness and/or asymmetric hearing loss<br>* Other names: MED-EL SYNCHRONY cochlear implant system;|
| Other: Control Group<br>A control group without the study intervention (cochlear implantation) will complete the test battery. | Other: Control Group<br>* Subjects in the control group will have had listening experience with a bone-conduction device, which is an approved treatment for SSD.<br>* Other names: bone-conduction device;|
| Experimental: Cochlear Implant: Asymmetric hearing loss<br>Cochlear implantation of the poorer hearing ear | Device: Cochlear Implant<br>* cochlear implantation used a treatment for single-sided deafness and/or asymmetric hearing loss<br>* Other names: MED-EL SYNCHRONY cochlear implant system;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Word Recognition in Quiet Over Time | Results on recorded speech perception materials: monosyllabic (Consonant-Nucleus-Consonant) words in quiet during the first year of device use. | Intervals within the first year of device use (e.g., preoperative, and 1-, 3-, 6-, 9-, and 12-months post-activation) | 
| Change in Localization Results (Measured in Root-mean-squared (RMS) Error) Over Time | Subjects were asked to identify the noise source from an 11-speaker array with the cochlear implant on versus off. The intensity level of the stimulus was randomly varied (10 dB around 70 dB SPL) to limit the listener relying on level effects. Responses at each intensity level (i.e., 60, 70, and 80 dB SPL) for a given sound source (speaker) were combined (averaged). Results are reported in root-mean-squared (RMS) error. A lower value indicates better performance. Results are compared during the first year of cochlear implant use. | Intervals within the first year of device use (e.g., preoperative, and 1-, 3-, 6-, 9-, and 12-months post-activation) | 
| Change in Subjective Benefit (Measured With the Speech, Spatial, and Qualities (SSQ) of Hearing Questionnaire) Over Time | Subjects completed subjective questionnaires in order to evaluate the perceived benefits of cochlear implantation. For the Speech, Spatial, and Qualities of hearing questionnaire, participants rank their perceived abilities on a scale of 0-10. Higher values indicate more perceived abilities. Results are reported as the total score at each interval, which is the average of the responses from all questions for the questionnaire. | Intervals within the first year of device use (e.g., preoperative, and 1-, 3-, 6-, 9-, and 12-months post-activation) | 
| Change in Sentence Recognition in Noise Over Time, Measured With the AzBio Sentences With Speech Presented From the Front and Noise Towards the Better Hearing Ear | Results on recorded speech perception materials: sentence recognition in noise with the target (speaker) from the front and the 10-talker masker 90 degrees towards the normal/better hearing ear. Scored as the percent correctly repeated. | Intervals within the first year of device use (e.g., preoperative, and 1-, 3-, 6-, 9-, and 12-months post-activation) | 
| Change in Localization Results (Measured in Variable Error) Over Time | Subjects were asked to identify the noise source from an 11-speaker array with the cochlear implant on versus off. The intensity level of the stimulus was randomly varied (10 dB around 70 dB SPL) to limit the listener relying on level effects. Responses at each intensity level (i.e., 60, 70, and 80 dB SPL) for a given sound source (speaker) were combined (averaged). Results are reported in variable error. A lower value indicates better performance. Results are compared during the first year of cochlear implant use. | Intervals within the first year of device use (e.g., preoperative, and 1-, 3-, 6-, 9-, and 12-months post-activation) | 
| Change in Localization Results (Measured in Constant Error) Over Time | Subjects were asked to identify the noise source from an 11-speaker array with the cochlear implant on versus off. The intensity level of the stimulus was randomly varied (10 dB around 70 dB SPL) to limit the listener relying on level effects. Responses at each intensity level (i.e., 60, 70, and 80 dB SPL) for a given sound source (speaker) were combined (averaged). Results are reported in constant error. A lower value indicates better performance. Results are compared during the first year of cochlear implant use. | Intervals within the first year of device use (e.g., preoperative, and 1-, 3-, 6-, 9-, and 12-months post-activation) | 
| Change in Localization Results (Measured in Adjusted Constant Error) Over Time | Subjects were asked to identify the noise source from an 11-speaker array with the cochlear implant on versus off. The intensity level of the stimulus was randomly varied (10 dB around 70 dB SPL) to limit the listener relying on level effects. Responses at each intensity level (i.e., 60, 70, and 80 dB SPL) for a given sound source (speaker) were combined (averaged). Results are reported in adjusted constant error. A lower value indicates better performance. Results are compared during the first year of cochlear implant use. | Intervals within the first year of device use (e.g., preoperative, and 1-, 3-, 6-, 9-, and 12-months post-activation) | 
| Change in Subjective Benefit (Measured With the Abbreviated Profile of Hearing Aid Benefit (APHAB) Questionnaire) Over Time | Subjects completed subjective questionnaires in order to evaluate the perceived benefits of cochlear implantation. For the Abbreviated Profile of Hearing Aid Benefit, participants rank their perceived difficulty on a scale of 1-99, with lower values indicate less perceived difficulty. The global score is average response across questions for the ease of communication, reverberation, and effectiveness in background noise subscales. | Intervals within the first year of device use (e.g., preoperative, and 1-, 3-, 6-, 9-, and 12-months post-activation) | 
| Change in Subjective Benefit (Measured With the Tinnitus Handicap Inventory (THI) of Hearing Questionnaire) Over Time | Subjects completed subjective questionnaires to order to evaluate the perceived benefits of cochlear implantation. For the Tinnitus Handicap Inventory, participants rank their perceived tinnitus severity on a scale of 0-100, with lower values indicate less tinnitus severity. Responses across all questions are summed to derive the total score. | Intervals within the first year of device use (e.g., preoperative, and 1-, 3-, 6-, 9-, and 12-months post-activation) | 
| Change in Sentence Recognition in Noise Over Time, Measured With AzBio Sentences With Speech Presented From the Front and Noise Towards the Poorer Hearing Ear (Implanted Ear) | Results on recorded speech perception materials: sentence recognition in noise with the target (speaker) from the front and the 10-talker masker 90 degrees towards the poorer hearing ear (implanted ear). Scored as the percent correctly repeated. | Intervals within the first year of device use (e.g., preoperative, and 1-, 3-, 6-, 9-, and 12-months post-activation) | 
| Change in Sentence Recognition in Noise Over Time, Measured With AzBio Sentences With Speech and Noise Presented From the Front | Results on recorded speech perception materials: sentence recognition in noise with the target (speaker) and the 10-talker masker from the front speaker. Scored as the percent correctly repeated. | Intervals within the first year of device use (e.g., preoperative, and 1-, 3-, 6-, 9-, and 12-months post-activation) | 
| Change in Sentence Recognition in Noise Over Time, Measured With Bamford-Kowal-Bamford (BKB) Sentences With Speech and Noise Presented From the Front | Results on recorded speech perception materials: sentence recognition in noise with the target (speaker) and the 4-talker masker from the front speaker. Scored as dB signal-to-noise ratio that the listener gets 50% speech understanding. Lower numbers indicate better performance (range -7.5 to 23.5 dB SNR). | Intervals within the first year of device use (e.g., preoperative, and 1-, 3-, 6-, 9-, and 12-months post-activation) | 
| Change in Sentence Recognition in Noise Over Time, Measured With Bamford-Kowal-Bamford (BKB) Sentences With Speech Presented From the Front and Noise Towards the Better Hearing Ear | Results on recorded speech perception materials: sentence recognition in noise with the target (speaker) from the front and the 4-talker masker 90 degrees towards the normal/better hearing ear. Scored as dB signal-to-noise ratio that the listener gets 50% speech understanding. A lower value indicates better performance (range -7.5 to 23.5 dB SNR). | Intervals within the first year of device use (e.g., preoperative, and 1-, 3-, 6-, 9-, and 12-months post-activation) | 
| Change in Sentence Recognition in Noise Over Time, Measured With Bamford-Kowal-Bamford (BKB) Sentences With Speech Presented From the Front and Noise Towards the Poorer Hearing Ear (Implanted Ear) | Results on recorded speech perception materials: sentence recognition in noise with the target (speaker) from the front and the 4-talker masker 90 degrees towards the poorer hearing ear (implanted ear). Scored as dB signal-to-noise ratio that the listener gets 50% speech understanding. Lower values indicate better performance (range -7.5 to 23.5 dB SNR). | Intervals within the first year of device use (e.g., preoperative, and 1-, 3-, 6-, 9-, and 12-months post-activation) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Aided Word Recognition With a Cochlear Implant Versus a Current Treatment Option (i.e., Hearing Aid) | Results on recorded speech perception materials: aided word recognition. Recorded 50-word CNC words were evaluated preoperatively with a conventional hearing aid. Performance was compared to the CI alone at the 12 month interval. A paired samples t-test compared the performance with the two devices. Percent correct data were converted to rationalized arcsine units (RAU) prior to data analysis to control for potential floor or ceiling effects (e.g., scores <20%). | preoperative interval and 12 month post-activation interval | 
| Localization Abilities With a Cochlear Implant Versus a Current Treatment Option (i.e., Bone-conduction Device) | Subjects were asked to identify the noise source from an 11-speaker array with the cochlear implant on versus with a bone-conduction device. The intensity level of the stimulus was randomly varied (10 dB around 70 dB SPL) to limit the listener relying on level effects. Responses at each intensity level (i.e., 60, 70, and 80 dB SPL) for a given sound source (speaker) were combined (averaged). Results are reported in root-mean-squared (RMS) error. A lower value indicates better performance. | Intervals within the first year of device use (e.g., preoperative, and 1-, 3-, 6-, 9-, and 12-months post-activation) | 
| Subjective Benefit (Measured With the Abbreviated Profile of Hearing Aid Benefit Questionnaire) With Cochlear Implant Versus Preoperative Perceptions With Alternative Treatment Options (e.g., Hearing Aid, Bone-conduction Device) | Subjects completed subjective questionnaires. For the Abbreviated Profile of Hearing Aid Benefit, participants rank their perceived difficulty on a scale of 1-99, with lower values indicate less perceived difficulty. The global score is the average response across questions for the ease of communication, reverberation, and effectiveness in background noise subscales. | preoperative interval, and post-activation intervals (1, 3, 6, 9, and 12 months) | 
| Subjective Benefit (Measured With the Tinnitus Handicap Inventory (THI) Questionnaire) With Cochlear Implant Versus Preoperative Perceptions With Alternative Treatment Options (e.g., Hearing Aid, Bone-conduction Device) | Subjects completed subjective questionnaires. For the Tinnitus Handicap Inventory, participants rank their perceived tinnitus severity on a scale of 0-100, with lower values indicate less tinnitus severity. Responses across all questions are summed to derive the total score. | Intervals within the first year of device use (e.g., preoperative, and 1-, 3-, 6-, 9-, and 12-months post-activation) | 
| Subjective Benefit (Measured With the Speech, Spatial, and Qualities of Hearing (SSQ) Questionnaire) With Cochlear Implant Versus Preoperative Perceptions With Alternative Treatment Options (e.g., Hearing Aid, Bone-conduction Device) | Subjects completed subjective questionnaires. For the Speech, Spatial, and Qualities of hearing questionnaire, participants rank their perceived abilities on a scale of 0-10. Higher values indicate more perceived abilities. Results are reported as the total score at each interval, which is the average of the responses from all questions for the questionnaire. | preoperative interval, and post-activation intervals (1, 3, 6, 9, and 12 months) | 
| Speech Perception Outcomes With a Cochlear Implant Versus a Bone-conduction Device: Sentence Recognition in Noise (AzBio, Speech Front and Noise Front) | Recorded AzBio sentences in a 10-talker masker were evaluated in 2 conditions: 1) bone-conduction device at the preoperative interval and 2) with the cochlear implant (CI) at the 12-month post-activation period. A paired samples t-test compared the performance with the two devices. Percent correct data were converted to rationalized arcsine units (RAU) prior to data analysis. | preoperative interval and 12 month post-activation interval | 
| Speech Perception Outcomes With a Cochlear Implant Versus a Bone-conduction Device: Sentence Recognition in Noise (AzBio, Speech Front and Noise to the Poorer Hearing Ear) | Recorded AzBio sentences in a 10-talker masker were evaluated in 2 conditions: 1) bone-conduction device at the preoperative interval and 2) with the cochlear implant (CI) at the 12-month post-activation period. A paired samples t-test compared the performance with the two devices. Percent correct data were converted to rationalized arcsine units (RAU) prior to data analysis. | preoperative interval and 12 month post-activation interval | 
| Speech Perception Outcomes With a Cochlear Implant Versus a Bone-conduction Device: Sentence Recognition in Noise (AzBio, Speech Front and Noise to the Better Hearing Ear) | Recorded AzBio sentences in a 10-talker masker were evaluated in 2 conditions: 1) bone-conduction device at the preoperative interval and 2) with the cochlear implant (CI) at the 12-month post-activation period. A paired samples t-test compared the performance with the two devices. Percent correct data were converted to rationalized arcsine units (RAU) prior to data analysis. | preoperative interval and 12 month post-activation interval | 
| Speech Perception Outcomes With a Cochlear Implant Versus a Bone-conduction Device: Sentence Recognition in Noise (BKB-Speech In Noise (SIN), Speech Front and Noise Front) | Recorded BKB sentences in a 4-talker masker were evaluated in 2 conditions: 1) bone-conduction device at the preoperative interval and 2) with the cochlear implant (CI) at the 12-month post-activation period. A paired samples t-test compared the performance with the two devices. Results are reported in dB SNR, where a lower value indicates better performance (range -7.5 to 23.5 dB SNR). | preoperative interval and 12 month post-activation interval | 
| Speech Perception Outcomes With a Cochlear Implant Versus a Bone-conduction Device: Sentence Recognition in Noise (BKB-SIN, Speech Front and Noise to the Poorer Hearing Ear) | Recorded BKB sentences in a 4-talker masker were evaluated in 2 conditions: 1) bone-conduction device at the preoperative interval and 2) with the cochlear implant (CI) at the 12-month post-activation period. A paired samples t-test compared the performance with the two devices. Results are reported in dB SNR, where a lower value indicates better performance (range -7.5 to 23.5 dB SNR). | preoperative interval and 12 month post-activation interval | 
| Speech Perception Outcomes With a Cochlear Implant Versus a Bone-conduction Device: Sentence Recognition in Noise (BKB-SIN, Speech Front and Noise to the Better Hearing Ear) | Recorded BKB sentences in a 4-talker masker were evaluated in 2 conditions: 1) bone-conduction device at the preoperative interval and 2) with the cochlear implant (CI) at the 12-month post-activation period. A paired samples t-test compared the performance with the two devices. Results are reported in dB SNR, where a lower value indicates better performance (range -7.5 to 23.5 dB SNR). | preoperative interval and 12 month post-activation interval | 
| Speech Recognition in Noise for a Control Group: AzBio Sentences (0 dB SNR) | The speech perception (cochlear implant recipients with UHL/SSD) to a control group of implantable bone-conduction device recipients (alternative treatment option). Participants in the control group had at least 12 months of listening experience with their implanted bone-conduction device prior to study participation. Sentence recognition was assessed in a 10-talker masker at 0 dB SNR with the target speech presented from the front and the masker (1) presented from the front (SoNo), (2) presented towards the implanted ear (SoNbc), and (3) presented towards the acoustic ear (SoNnh). Performance was scored as the percent of words correctly repeated, with higher values indicating better performance. The task was completed with the participants listening with their bone-conduction device on versus off. | Assessment completed after 12 months of implantable bone-conduction listening experience | 
| Speech Recognition in Noise for a Control Group: BKB-SIN Test | The speech perception outcomes in the study population (cochlear implant recipients with UHL/SSD) to a control group of implantable bone-conduction device recipients (alternative treatment option). Participants in the control group had at least 12 months of listening experience with their implanted bone-conduction device prior to study participation. Sentence recognition was assessed in a 4-talker masker with the target speech presented from the front and the masker (1) presented from the front, (2) presented towards the implanted ear, and (3) presented towards the acoustic ear. Performance was scored as the dB SNR when the participant understood 50% correct, with lower values indicating better performance. Participants completed the task with the device on and off. | Assessment completed after 12 months of implantable bone-conduction listening experience | 
| Localization for a Control Group | Subjects were asked to identify the noise source from an 11-speaker array with the bone-conduction device on versus off. The intensity level of the stimulus was randomly varied (10 dB around 70 dB SPL) to limit the listener relying on level effects. Responses at each intensity level (i.e., 60, 70, and 80 dB SPL) for a given sound source (speaker) were combined (averaged). Results are reported in root-mean-squared (RMS) error. A lower value indicates better performance. Subjects in the control group were implantable bone-conduction device recipients (alternative treatment option) with at least 12 months of listening experience with their implanted bone-conduction device. Participants completed the task with their device on and off. | Assessment completed after 12 months of implantable bone-conduction listening experience | 
| Subjective Benefit for a Control Group: Speech, Spatial, and Qualities of Hearing Scale (SSQ) | Subjects completed subjective questionnaires. For the Speech, Spatial, and Qualities of hearing questionnaire, participants rank their perceived abilities on a scale of 0-10. Higher values indicate more perceived abilities. Results are reported as the average responses across questions for each subscale (Speech Hearing, Spatial Hearing, and Qualities of Hearing). Results are also reported as the total score at each interval, which is the average of the responses from all questions for the questionnaire. Participants in the control group had at least 12 months of listening experience with their implanted bone-conduction device prior to study participation. | Assessment completed after 12 months of implantable bone-conduction listening experience | 
| Subjective Benefit for a Control Group: Abbreviated Profile of Hearing Aid Benefit (APHAB) | Subjects completed subjective questionnaires. For the Abbreviated Profile of Hearing Aid Benefit, participants rank their perceived difficulty on a scale of 1-99, with lower values indicate less perceived difficulty. Results are reported as the average responses for each of the four subscales: ease of communication, reverberation, effectiveness in background noise, and reverberation. The global score is the average response across questions for the ease of communication, reverberation, and effectiveness in background noise subscales. Participants in the control group had at least 12 months of listening experience with their implanted bone-conduction device prior to study participation. | Assessment completed after 12 months of implantable bone-conduction listening experience | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Unilateral hearing loss, Single Sided Deafness, Asymmetric hearing loss