Hearing Study: Sensitivity to Features of Speech Sounds

Study Overview
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Brief Summary
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The purpose of this study is to better understand the sensitivity of listeners to the fast changes in frequency or amplitude of sounds that occur in speech. The investigators are studying ways to manipulate these aspects of sounds in an effort to make speech sounds more clear.

Detailed Description
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The investigators will test listeners with normal hearing or with mild or moderate hearing loss. Tests will first focus on sensitivity to changes in fast changes in amplitude (loudness) or frequency (pitch) in sounds. Then the investigators will test the intelligibility of synthetic vowels and syllables in which these chirps are manipulated. Finally, the investigators will test intelligibility of words in noise while manipulating sounds in an effort to improve clarity.

Official Title
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Auditory Processing of Complex Sounds - Sensitivity to Chirps

Conditions
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Hearing Loss, Sensorineural

Intervention / Treatment
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* Other: Signal processing to improve intelligibility


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Normal hearing, mild or moderate symmetric sensorineural hearing loss. Exclusion Criteria: Asymmetric hearing thresholds (more than 15 decibels (dB) threshold difference between the two ears at any frequency up to 4 kHz). Severe hearing loss (greater than 60 dB hearing thresholds at any frequency up to 4 kHz).

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Normal Hearing<br>Signal processing to improve intelligibility | Other: Signal processing to improve intelligibility<br>* Signal processing will be used to manipulate frequency and amplitude fluctuations in complex sounds.<br>|
| Active Comparator: Mild hearing loss<br>Signal processing to improve intelligibility | Other: Signal processing to improve intelligibility<br>* Signal processing will be used to manipulate frequency and amplitude fluctuations in complex sounds.<br>|
| Active Comparator: Moderate hearing loss<br>Signal processing to improve intelligibility | Other: Signal processing to improve intelligibility<br>* Signal processing will be used to manipulate frequency and amplitude fluctuations in complex sounds.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Discrimination thresholds for formant-freq difference limens | Measures of discrimination thresholds (in units of % of Formant Frequency at the discrimination threshold) for different formant bandwidths and for different alignments of formants and harmonics. | 5 years | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| % of correct synthetic vowels | % correct answers | 5 years | 
| % of correct synthetic syllables | % correct answers | 5 years | 
| % of correct words | % correct answers using SPiN test | 5 years |