Acoustic Analysis of Emotional Speech Processed by Hearing Aids

A talker’s emotional state is one important type of information carried by the speech signal. Past studies have shown that listeners with hearing loss have difficulties identifying vocal emotion. However, there is little research on how much hearing aids may ameliorate these difficulties. The amplitude compression performed by hearing aids makes words easier to recognize, but little is known about how such processing affects the emotional cues carried in the speech signal. The speech materials used in this study were sentences spoken by a young female actor portraying different vocal emotions. These sentences were processed using different hearing aid simulations: a flat 10 dB gain across frequencies; linear gain according to NAL-NL2 targets; fast amplitude compression, and slow amplitude compression. Acoustic analyses of the hearing aid-processed speech showed that the amplitude envelope was flattened by fast amplitude compression, more so for sentences spoken in Angry and Happy conditions than in other emotion conditions. Hearing aid processing using NAL-NL2 targets also led to an increase in the amount of high-frequency energy, more so for sentences spoken in Neutral and Sad conditions than in other emotion conditions. We conclude that amplitude processing by hearing aids is beneficial for audibility but potentially detrimental for emotion understanding.