Amplification and Assistive Devices (AAD)
Joslyn A. Parsons, MS (she/her/hers)
Clinical Extern
University of Nebraska-Lincoln; VA Puget Sound Healthcare System
Federal Way, Washington
Financial Disclosures: I do not have any relevant financial relationships with anything to disclose.
Non-Financial Disclosures: I do not have any relevant non-financial relationships with anything to disclose.
Marc Brennan, PhD (he/him/his)
Assistant Professor
University of Nebraska-Lincoln
University of Nebraska-Lincoln, Nebraska
Financial Disclosures: I do not have any relevant financial relationships with anything to disclose.
Non-Financial Disclosures: I do not have any relevant non-financial relationships with anything to disclose.
Emma Wilken, AuD (she/her/hers)
Audiologist
ENT Physicians of Kearney
Kearney, Nebraska
Financial Disclosures: I do not have any relevant financial relationships with anything to disclose.
Non-Financial Disclosures: I do not have any relevant non-financial relationships with anything to disclose.
Sensorineural hearing loss negatively impacts localization abilities, and prior work has documented a poorer ability for users to perceive the interaural level difference. However, prior work sometimes used hearing aid settings that would rarely be used clinically. To determine how localization might be affected by amplification, this study examined the effects of compression attack and release times and prescriptive procedure on the ability of adults with sensorineural hearing loss to perceive the interaural level difference (ILD). Results showed that unaided conditions yielded better perception of ILDs than when using compression amplification, which is consistent with previous work.
Summary:
Rationale: Localization suffers with sensorineural hearing loss, partially due to reduced access to the interaural level difference (ILD) cue. While hearing aids use wide-dynamic-range compression (WDRC) to restore audibility of speech sounds and decrease the negative effects of loudness in individuals with hearing loss, previous studies have observed WDRC to negatively impact the perception of ILDs. This effect possibly contributes to poorer localization with amplification. However, previous work used the same compression ratio for all hearing aid channels without considering individual differences in hearing loss. As such, this study focused on the effects of compression speed and prescriptive procedure on the perception of ILDs.
Methods: 29 adult participants with sensorineural hearing loss were recruited to determine the effects of prescriptive procedure and compression speed on the perception of ILDs. Output levels for a hearing aid simulator were set to the Desired Sensation Level (DSL) acquired and congenital prescriptions (DSLA and DSLC, respectively) targets using participants’ thresholds. Participants were asked to indicate which 4000 Hz stimuli were coming most from the right in a 3-interval 3-alternative-forced choice paradigm under headphones.
Results: We hypothesized that 1) ILD thresholds would be better in unaided conditions, and when aided, using faster compression speeds, and 2) linear amplification based off DSLC would provide better access to ILDs and therefore better localization performance due to higher audibility provided by DSLC. The contributions of compression, compression speed, and prescriptive procedure to ILD perception were assessed using a series of linear mixed effects models. It was observed that ILD thresholds were significantly better unaided than aided. It was further observed that ILD thresholds were better with DSLA than DSLC. While compression amplification, including compression speed, did not impact ILD thresholds when using DSLA, ILD thresholds were significantly poorer with fast compression when using DSLC.
Conclusions: This work extended prior work by using compression ratios set to two different prescriptive procedures. Consistent with prior work, WDRC degraded ILD thresholds. However, the extent of degradation to ILD thresholds depended on the prescriptive procedure. These results suggest that poorer perception of ILD cues with amplification could contribute to the previously observed poor localization ability of hearing aid users. Implications for clinical practice will be discussed.