Singing power ratio: quantitative evaluation of singing voice quality.

This paper presents a parameter for objectively evaluating singing voice quality. Power spectrum of vowel sound /a/ was analyzed by Fast Fourier Transform. The greatest harmonics peak between 2 and 4 kHz and the greatest harmonics peak between 0 and 2 kHz were identified. Power ratio of these peaks, termed singing power ratio (SPR), was calculated in 37 singers and 20 nonsingers. SPR of sung /a/ in singers was significantly greater than in nonsingers. In singers, SPR of sung /a/ was significantly greater than that of spoken /a/. By digital signal processing, power spectrum of sung /a/ was varied, and the processed sounds were perceptually analyzed. SPR had a significant relationship with perceptual scores of "ringing" quality. SPR provides an important quantitative measurement for evaluating singing voice quality for all voice types, including soprano.