Spectrographic and perceptual features of vocal tension/harshness in hearing-impaired adults

Twenty hearing-impaired adult males exhibiting a range of severity of vocal tension/harshness sustained the vowels /a/ and /u/, at a constant intensity level and read the first two sentences of the Rainbow Passage. Recordings of the vowels and sentences were rated for degree of severity of vocal tension/harshness on a 5-point, equal-appearing-interval scale by three speech pathologists. Each vowel production was analyzed to produce a narrow-hand (10 Hz) frequency-by-amplitude acoustic spectrum in which the levels of inharmonic energy, i.e., noise components, were measured in dB SPL over the frequency range 100--3000 Hz. Significant correlations were obtained between: mean ratings of vocal tension for sentences and for vowels; mean ratings of vocal tension for vowels and average spectral noise levels for vowels; and mean ratings of vocal tension for sentences and average spectral noise levels for vowels.