Auditory and non-auditory factors contributing to the benefit of amplification

Among individuals with hearing impairment there exist large differences in the benefit of amplification with hearing aids in understanding speech in noise. For rehabilitation success, explaining this variability is fundamental. To address the issue, we investigated n=92 elderly individuals with a mild-to-moderate hearing loss who completed a test battery comprising auditory and cognitive tests, a test measuring the capacity of audiovisual integration, and a questionnaire. The speech intelligibility based benefit of amplification was defined as the difference between unaided and aided 80%-SRT measurements (Goettingen sentence test [1], ICRA5-250 noise [2], amplification applied via the master hearing aid [3]). While n=55 participants were already aided with hearing devices before entering the study (hearing aid users, HA-U), the remaining n=37 individuals were completely inexperienced in using hearing aids (hearing aid non-users, HA-NU).

Preliminary results from statistical learning methods suggest that influential factors differ as a function of the amount of balancing HA-U and HA-NU with respect to the degree of hearing loss: The more the groups are matched regarding hearing performance, the more relevant are cognitive measures as well as audiovisual integration. Beyond controlling for the degree of hearing loss, however, further possible confounder variables should be taken into account, such as self-reported hearing problems, subjective listening effort, and the influence of hearing problems on quality of life. Therefore, we apply propensity score matching [4], a well-known matching method in fields such as epidemiology and medicine, making both hearing aid users and non-users more comparable.

References:

[1] Kollmeier, B., and Wesselkamp, M. (1997). Development and evaluation of a German sentence test for objective and subjective speech intelligibility assessment. The Journal of the Acoustical Society of America 102, 2412-2421.

[2] Wagener, K. C., Brand T., and Kollmeier B. (2006). The role of silent intervals for sentence intelligibility in fluctuating noise in hearing-impaired listeners. International Journal of Audiology 45(1), 26-33.

[3] Grimm, G., Herzke, T., Berg, D., and Hohmann, V. (2006). The master hearing aid: a PC based platform for algorithm development and evaluation. Acta acustica united with Acustica 92, 618-628.

[4] Rosenbaum, P. R., and Rubin, D. B. (1983). The central role of the propensity score in observational studies for causal effects. Biometrika 70, 41–55.