Harmonic Levels and Vowel Roughness In this study the effects of vowel roughness on the level of harmonics in test vowel spectra were investigated. Twenty normal-speaking adult males sustained productions of each of the vowels /u/, /i/, /Λ/, /a/, and /æ/ first normally and then with simulated abnormal vocal roughness, at one intensity. A tape ... Research Article
Research Article  |   December 01, 1979
Harmonic Levels and Vowel Roughness
 
Author Affiliations & Notes
  • Floyd W. Emanuel
    University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
  • Robert L. Whitehead
    National Technical Institute for the Deaf, Rochester, New York
Article Information
Research Articles
Research Article   |   December 01, 1979
Harmonic Levels and Vowel Roughness
Journal of Speech, Language, and Hearing Research, December 1979, Vol. 22, 829-840. doi:10.1044/jshr.2204.829
History: Received September 25, 1978 , Accepted January 15, 1979
 
Journal of Speech, Language, and Hearing Research, December 1979, Vol. 22, 829-840. doi:10.1044/jshr.2204.829
History: Received September 25, 1978; Accepted January 15, 1979

In this study the effects of vowel roughness on the level of harmonics in test vowel spectra were investigated. Twenty normal-speaking adult males sustained productions of each of the vowels /u/, /i/, /Λ/, /a/, and /æ/ first normally and then with simulated abnormal vocal roughness, at one intensity. A tape recording of each production was rated for roughness on an equal-appearing intervals scale by 11 judges and was also analyzed to obtain its 3-Hz bandwidth amplitude-by-frequency acoustic spectrum. The median roughness rating, the level of the first five spectral harmonics, and the fo of each production were obtained. It was found that the level of the first three harmonics for each test vowel diminished with an increase in roughness (as was hypothesized from earlier results), but the higher harmonics of /u/ and /i/ showed some reversals. A moderately large negative correlative relationship was shown between lower-harmonic levels and median vowel roughness. A possible explanation of the higher-harmonic reversals was offered. The results suggest that spectral noise level measurements may provide a more reliable acoustic index of vowel wave aperiodicity and vowel roughness than measurements of harmonic level.

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