2022/10/25 by Herrmann, Jessica, Wollermann, Simone, Jürgens, Tim +1
#Hörsysteme #Lärmschutz #Medicine and health #Schwerhörige #Tages-Schallexpositionspegel #daily noise exposure level #hearing aids #hearing impaired #hearing protection
paper · doi:10.3205/zaud000025
Intentional and unintentional everyday noises, such as traffic noise or music, contribute to people's noise exposure. The average noise exposure of people with normal hearing has been recorded and evaluated in several studies. However, the influence of a hearing aid was not considered. This study examined the influence of a hearing aid on the daily sound exposure level in everyday life. This was done in two steps. First, hearing aid output levels were recorded on an artificial head at frontal 0° sound exposure for different signals and signal levels and different hearing losses. Based on these data, the influence of the signal type, the signal level and the type of hearing loss on the output levels were investigated. Next, typical every-day scenarios were composed from these signals and the corresponding accumulated daily sound exposure levels were determined based on the measured output levels. This data was used not only to investigate how the daily sound exposure level is affected by the hearing aid processing, but also to estimate the effect of an increased daily sound exposure level using the ISO 1999:2013 models. The studies confirm that with increasing hearing loss, a stronger compression ratio is needed to compress the signal into the dynamic range of the hearing impaired user. When the relationship between hearing aid gain and signal type is considered, only small differences were observed. The daily sound exposure level was only increased by the hearing aid when fitted to stronger hearing losses such as N4 and S2 according to DIN EN 60118-15 compared to normal hearing listeners exposed to the same input signals. As soon as the hearing aid was adjusted to milder hearing losses, the daily sound exposure level remained almost the same or was even reduced due to closed fitting with ear moulds. The level of the sound exposure level was significantly influenced by the situation with the highest level and/or the longest duration. When estimating the consequences of the increased daily sound exposure level due to hearing aids according to ISO 1999:2013, strong effects were especially noticeable when the amplification was higher than necessary according to the hearing loss. For this purpose, a worst-case scenario was investigated in which a person with normal hearing would use a hearing aid with an amplification adjusted for a certain hearing loss for 10 years. In comparison, the impact was negligible if the amplification was adjusted according to the hearing loss. This is because the risk of further hearing damage according to ISO 1999:2013 is smaller with increasing pre-existing hearing loss. When fitting hearing aids, care should therefore be taken to ensure that the amplification of a hearing aid is always selected according to the individual hearing loss.