Amplification and Assistive Devices (AAD)
Lauren G. Secilmis, BS
University of Nebraska-Lincoln
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.
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.
Sarah Garvey, BS
Graduate Research Assistant
University of Nebraska-Lincoln
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.
Rationale: The majority of hearing losses are higher (worse) in the high frequencies. Due to limited gain, current hearing aid technology prevents effective high frequency audibility. Non-linear frequency compression (NLFC) is a type of frequency lowering that attempts to remedy the limited bandwidth of hearing aids. Given an increase in high frequency information, it is presumed that speech recognition and localization, due to improved audibility of interaural level and phase differences, should improve. However, previous work is inconclusive on the effects of this processing strategy on speech recognition. In addition, only one study examined the influence of NLFC on localization cues and behavioral measures were not obtained. The current work attempts to add additional evidence by examining possible relationships between: (1) NLFC and speech recognition and (2) localization ability.
Methods: Adult participants (mean age: 58) were recruited to determine the effect of Phonak’s form of NLFC, called SoundRecover II, on speech recognition and localization ability. Participants had sensorineural hearing loss ranging from mild to moderately-severe. Participants wore Phonak Audeo M90 receiver-in-canal hearing aids with medium strength receivers and appropriate acoustic coupling based on their degree of hearing loss. Hearing aids were programmed to DSL-A targets using simulated real ear with a Verifit 2 hearing aid analyzer. All other advanced processing settings were disabled in an attempt to isolate the effect of NLFC. In a randomized paradigm, for one visit, participants had NLFC activated and for another visit, NLFC was deactivated. Participants were positioned 0-degree azimuth in a forty-seven speaker array in a room with sound attenuating paneling. Speakers were arranged ten and twenty degrees apart, respectively, for the bottom and top rows which allowed for examination of both vertical and horizontal errors in localization. Sentence recognition was measured using four AzBio sentence lists for each condition (NLFC-on, NLFC-off).
Results: While data collection is ongoing, there was a significant difference between the mean proportion of words correct, with NLFC-on greater than NLFC-off. There was no significant difference in localization ability between the two conditions. Specifically, proportion correct identification of location was statistically equivalent when NLFC was activated and deactivated for both horizontal and vertical locations.
Conclusions: It can be concluded that the addition of NLFC had a positive effect on access to high frequency speech information given the improvement in speech recognition when NLFC was activated. Moreover, benefit may have been limited due to near ceiling performance. While access to interaural level and phase cues may have improved with NLFC, such an improvement, if present, did not improve localization ability. Additional data are being collected, with a goal of 12 participants to present.