The objective of this study protocol is to determine the efficacy of using aided measures of spectral resolution to set the dynamic range of hearing with hearing-aid amplification. Measures of spectral resolution will be obtained, as will measures of speech recognition.
Adults with hearing loss are more vulnerable to interference from background noise than adults with normal hearing. Despite the fact that the ability to extract speech information imbedded in background noise requires decoding differences in level across frequency (spectral information), few studies have addressed the extent to which spectral information can be provided to listeners with hearing loss. This fundamental gap in our knowledge prevents society from effectively addressing the systemic effects of hearing loss on communication, income, and ability to socialize with others. This work is a new application of established methods of characterizing spectral resolution to that of the most common device for rehabilitation of hearing loss, hearing-aid amplification. Because hearing aids do not require premarket approval, FDA oversight is not applicable to this clinical trial. The experiments will examine the degree to which access to spectral information can be restored to adults with hearing loss and the feasibility of utilizing this information to decrease interference from background noise. Aim 1 will delineate the impact of hearing-aid amplification on spectral decoding. Technology options that must be set by the clinician or hearing-aid manufacturer will be examined, including the frequency-specific gain, compressor speed, and number of compression channels. The proposed experiments will test the hypothesis that restoration of the lost dynamic range of hearing can support the encoding of spectral information. It is also hypothesized that the combination of technology options that best restore access to spectral information will differ across individuals and that these differences across individuals can be partially accounted for by an estimate of outer hair cell function. Aim 2 will determine the extent to which restoring access to spectral information supports speech recognition in background noise, under the guiding hypothesis that improving spectral resolution increases speech understanding. If it can be demonstrated that measures of spectral resolution with the provision of amplification are useful at delineating those who stand to benefit from different technology options, the knowledge gained could then be applied to the clinic to allow for clinicians to more successfully choose among different rehabilitation options.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
209
Hearing Aid
Barkley Memorial Center
Lincoln, Nebraska, United States
Spectral Resolution
Measure of spectral resolution (Q10) obtained from the fast psychophysical tuning curve test. For this study, Q10 was computed as the target frequency divided by the bandwidth of the tuning curve (10 dB above the threshold at the tip of the tuning curve test). Higher numbers on this scale indicate sharper (better) tuning. The lower limit for this scale is 0 and there is no upper limit.
Time frame: Each test was approximately 10 minutes and was completed after each experimental manipulation
Speech Recognition
measure of spatial release from masking (dB) for a masker presented at 70 dB SPL.
Time frame: Each test was approximately 10 minutes and was completed after each experimental manipulation
Working Memory
Measure of working memory (correctly repeated words from the reading span test). The minimum (poorer) and maximum (better) values are 0 and 57, respectively.
Time frame: Each test was approximately 30 minutes and was completed only once per subject.
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