Subjective evaluation of speech intelligibility for normal-hearing persons and for persons with simulated minimal degrees of hearing loss

摘要

The "acoustics" of a classroom is one of the important factors that influence the educational achievement of children. Especially for hearing-impaired children good acoustical conditions are essential. It is well recognized [1] that thesechildren, in a higher degree than normal hearing children, are affected by a poor acoustical environment due to long reverberation times and/or high background noise levels.The aim of this work has been to investigate how subjectively perceived speech intelligibility is influenced by different types of ordinary absorber treatment in a classroom. Especially the relation between subjectively perceived speech intelligibilityand reverberation time respectively RASTI-values have been investigated. A listening test has been carried out in order to classify the different treatments in respect to achieved speech intelligibility. The listening test has been performed by two groups of subjects. One group consist of normal hearing individuals. The other group consist of subjects that listened to the test with special earplugs attached to their ears. The earplugs have been used in order to simulate a minimal degree of hearing loss.With minimal degrees of hearing loss is meant a pure tone threshold between 15 and 30 dB hearing loss. This type of hearing loss is often a secondary effect of a cold or an inflammation and usually of a temporary nature.