gms | German Medical Science

Multiple studies have shown the adverse effects of wearing hearing aids in normal-hearing adults, including disadvantages for spatial hearing and speech intelligibility. These effects can partly explain limited hearing aid acceptance in users with mild or moderate hearing loss, while their origin is partly unclear. An example is an observed reduction in speech intelligibility of about 1 dB with collocated speech and noise, where listening through a hearing aid does not modify the SNR at the ear [1], [2]. To gain further understanding of this hearing aid disadvantage, we studied speech perception with 9 different hearing devices in 18 normal-hearing adults. Six commercial hearing aids and one research hearing aid (PHL – Portable Hearing Lab) were individually programmed to be as transparent as possible by fitting it close to 0 dB insertion gain. The PHL was also used in the same generic setting, as in one of the previous studies [1]. Further, we included wearable headphones with a transparency mode. Measurements comprised speech reception thresholds using the OLSA sentence test, and subjective listening effort ratings using the ACALES procedure. All measurements were conducted with both the open ear and while wearing the devices, with speech and noise collocated at the front.

The results verify a negative effect of transparent hearing aids on speech intelligibility; however, it was significantly reduced by individually fitting the hearing aids. Further, it could be shown that the negative effect on speech intelligibility increases with an increasing difference to the open-ear behaviour. The results for the subjective listening effort are less conclusive, for reasons that remain to be discussed.