Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Date of Graduation

Spring 2018

Document Type


Degree Name

Doctor of Audiology (AuD)


Department of Communication Sciences and Disorders


Ayasakanta Rout

Rory A. DePaolis

Yingjiu Nie


This ongoing study compared premium and mid-level hearing aids from major manufacturers on noise reduction and general electroacoustic characteristics. The findings of this study will contribute to the scarce independent literature evaluating currently available hearing aid technology. Measuring the overall gain reduction in response to a steady state noise can objectively test noise reduction. However, such a method does not specifically test a hearing aid’s ability to reduce speech in specific narrow frequency bands. Hanline & Rout (2008) developed a set of stimuli to evaluate multichannel noise reduction algorithms more precisely. We used these stimuli to test noise reduction abilities of hearing aids. Premium and mid level digital hearing aids from four major manufacturers were obtained and programmed for mild to moderately severe sloping SNHL using the manufacturer’s proprietary fitting formula.

Each hearing aid was programmed for noise reduction ON and OFF with every other feature disabled (or minimized). Hearing aid programming was verified, and each hearing aid was tested twice for reliability. Three different bandwidths of steady-state noise (1/3 oct, 1 oct, 2 oct) were embedded at six different frequencies (0.5, 1, 2, and 4 kHz) resulting in 12 new stimuli. In addition, a 30 second steady state speech shaped noise was included to evaluate the attack time and overall gain reduction of each noise reduction algorithm.

The findings of this study suggest that there is no difference between the noise reduction efficiency of a premium level hearing aid when compared to a mid-level instrument at reducing steady state background noise. The frequency specific data indicated that there was a significant difference in the noise reduction capabilities of a mid-level and premium level hearing instrument when the background noise included both speech and background noise, as simulated by the ICRA stimuli. ICRA stimuli was created by the International Collegium for Rehabilitative Audiology for the purpose of analyzing hearing aids, as it employs spectra shaped speech like noise (Dreschler et al., 2001). There was also a significant interaction between technology level and noise bandwidth as well as a significant main effect of noise bandwidth.



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