Development of speech in noise and reverberation test with multichannel auralizations.
In recent years, a major step forward in improving hearing diagnostics in Finland has been the development and implementation of a new Finnish sentence-in-noise test. This test has greatly improved the accuracy of hearing diagnostics and quality control of hearing rehabilitation in Finland. However, the test stimuli are presented over headphones or via loudspeakers in a sound booth with little to no reverberation. In contrast, people often report on difficulties specifically in understanding speech in every day reverberant conditions. Advanced spatial sound technologies may provide means to study speech perception in a variety of acoustical conditions and may help to further understand speech perception in noise and in reverberation considering both normally hearing listeners and listeners with various degree of hearing impairments. The aim of this project is to investigate how advanced spatial sound technologies could be used in hearing diagnostics and to develop novel tools with more complex and authentic sound scenes. In hearing diagnostics and rehabilitation, faithful representation of the spectral characteristics of complex sound scenes is of paramount importance.
A recently developed auralization method (Spatial Decomposition Method) with minimal spectral coloration artefacts may be well suited for bringing advanced spatial sound technology into clinically feasible environments. Here, we present preliminary results of our study, where we have used the Finnish sentence-in-noise test with multichannel auralizations of two real spaces (with approx. one and two second reverberation times) in order to compare the speech reception thresholds (SRTs) between anechoic and reverberant conditions. Currently the test has been taken by 29 test subjects, including 13 normal hearing and 16 hearing impaired listeners. The results do not indicate significant differences in SRTs between anechoic and reverberant conditions, but considering the hearing impaired, there seems to be a small improvement in SRT when measured in reverberation time of approx. one second. The tests are on-going and we are currently collecting results of patients with more severe hearing impairments and patients with hearing aids.