Impact of Distance on Acoustic Features of Speech and Its Effect on Speech Perception in Sensorineural Hearing Loss With and Without Hearing Aids

Abstract

The inability to comprehend speech at a distance, even with the use of a hearing aid, is a common complaint seen in individuals with hearing impairment. The study was done to determine the effect of distance on acoustic features and speech understanding in individuals with hearing impairment in both unaided and aided condition. In the first phase, the recorded sentences were played at the intensity compensated for the propagation loss and it was recorded using a Sound Level Meter (SLM) at three distances 1m, 3m, and 5m. The recordings obtained were analyzed to see if any acoustical features changes with the increase in distance using the Harmonic to noise ratio (HNR), Cepstral Peak Prominence, Long-term average spectrum (LTAS), LTAS tilt, LTAS slope and Envelope difference index (EDI). In the second phase, the speech identification scores were measured in twenty-one participants with moderate sensorineural hearing loss in unaided and aided conditions using the same presentation levels as in the first phase. The results showed that HNR was reduced, a slightly increasing trend was seen in CPP, LTAS showed an increase in the energy of high frequency, LTAS tilt showed a slightly decreasing trend, LTAS slope showed a reduction, and the EDI increased with increase in the distance. The speech identification scores were significantly better in aided condition, but there was significant reduction in the speech identification scores with increasing distance in both aided and unaided condition. These results could be attributed to the modification in the acoustic parameters in both spectral and envelope domain with respect to the distance, which would have led to the reduction in the speech identification scores in moderate sensorineural hearing loss.