Clin Exp Otorhinolaryngol.  2015 Sep;8(3):237-242. 10.3342/ceo.2015.8.3.237.

Benefit From Directional Microphone Hearing Aids: Objective and Subjective Evaluations

• Park HS
• Moon IJ
• Jin SH
• Choi JE
• Cho YS
• Hong SH

• KMID: 2117518
• DOI: http://doi.org/10.3342/ceo.2015.8.3.237

Abstract

OBJECTIVES
The aims of this study were to find and compare the effect of directional (DIR) processing of two different hearing aids via both subjective and objective methods, to determine the association between the results of the subjective and objective evaluations, and to find out individual predictive factors influencing the DIR benefit.
METHODS
Twenty-six hearing aid users fitted unilaterally with each two different experimental hearing aid performed modified Korean Hearing in Noise Test (K-HINT) in three DIR conditions; omnidirectional (OMNI) mode, OMNI plus noise reduction feature, fixed DIR mode. In order to determine benefits from DIR benefit within a hearing aid and compare performance of the DIR processing between hearing aids, a subjective questionnaire was administrated on speech quality (SQ) and discomfort in noise (DN) domain. Correlation analysis of factors influencing DIR benefit was accomplished.
RESULTS
Benefits from switching OMNI mode to DIR mode within both hearing aids in K-HINT were about 2.8 (standard deviation, 3.5) and 2.1 dB SNR (signal to ratio; SD, 2.5), but significant difference in K-HINT results between OMNI and OMNI plus noise reduction algorithm was not shown. The subjective evaluation resulted in the better SQ and DN scores in DIR mode than those in OMNI mode. However, the difference of scores on both SQ and DN between the two hearing aids with DIR mode was not statistically significant. Any individual factors did not significantly affect subjective and objective DIR benefits.
CONCLUSION
DIR benefit was found not only in the objective measurement performed in the laboratory but also in the subjective questionnaires, but the subjective results was failed to have significant correlation with the DIR benefit obtained in the K-HINT. Factors influencing individual variation in perceptual DIR benefit were still hard to explain.

Keyword

Hearing Loss; Hearing Aids; Speech Intelligibility; Signal-To-Noise Ratio

MeSH Terms

Hearing Aids*
Hearing Loss
Hearing*
Noise
Signal-To-Noise Ratio
Speech Intelligibility

Figure

• 

  Fig. 1 Mean hearing thresholds for a test ear in unaided and aided condition, as a function of the given frequencies. The blue circles show unaided responses. The yellow circles and inverted green triangles describe A and B aided response. Error bars indicate ±1 SD about the mean across subjects. HL, hearing loss.

• 

  Fig. 2 Signal to noise ratio (dB SNR) of Korean hearing-in-noise test as a function of each test condition measured in hearing aid A and hearing aid B. The conditions were classified under 4 heads; omnidirectional (OMNI) mode, OMNI mode plus noise reduction (NR), directional (DIR) mode, and benefit from switching OMNI mode to DIR mode. Error bars indicate ±1 SD about the mean across subjects.

• 

  Fig. 3 Mean scores on speech quality and discomfort in noise in condition (A) and (B). The higher scores mean better speech quality and strong discomfort in noise. In condition (A) comparing an omnidirectional (OMNI) mode with a fixed directional (DIR) mode within hearing aid (HA) A, the blue bar indicates the mean scores using OMNI mode whereas the yellow bar appears the mean scores using the DIR mode. In condition (B) which makes a comparison of DIR mode between HA A and B, the score of HA A is expressed in the blue bar while that of HA B is showed as the yellow bar. Error bars indicate±1SD.

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