Abstract:
Individuals with hearing impairment have a major complaint of understanding speech from a distance, even after using a hearing aid. To determine the cause of the problem, a study was conducted to see if any spectral features changes over distance, affecting understanding speech from a distance. The study was carried out in three phases. In the first phase, the intensity required for the person to understand speech from three different distances was identified. In the second phase, the recorded speech in the first phase across three distances was acoustically analysed to see if any spectral features changes with the increase in distance using Long Term Average Spectrum (LTAS), Cepstral Peak Prominence (CPP), and Harmonic to Noise ratio (HNR) measures. In the third phase, the Speech identification scores (SIS) were identified in both unaided and aided conditions across three distances using the average intensity level obtained in the first phase. The results showed that the average intensity level was increased with an increase in distance. The acoustic analysis of LTAS revealed that with an increase in distance, the energy in the higher harmonics was increased, but CPP was similar, and HNR was reduced with an increase in distance. In the third phase, the Speech identification scores were similar at 1m and 3m, but it was reduced at 5m, as seen in both the unaided and aided condition and the scores in the aided condition improved compared to the unaided condition. However, the speech identification scores were less at 5m compared to 1m and 3m. The CPP was similar, and HNR reduced across distance, indicating the addition of noise with increased distance. The study concluded that as distance increases, the SNR decreases, which can be the factor affecting understanding speech from a distance.
