Methods of Measuring Speech Formant Bandwidths
Hugh K. Dunn · The Journal of the Acoustical Society of America · 1961
Accurate measurements of the human vocal tract damping, or the associated formant bandwidths, are not easy. Several different methods have been used by experimenters, with rather widely divergent results. Some of these methods are examined for sources of error, and the conclusions are checked by applying the same methods to the electrical vocal tract. This analog of the human tract can be held constant during a test, can be adjusted in damping, and can be measured accurately by single frequencies. More exact measurement of the real tract would seem to require an artificial source, applied in the pharyngeal cavity, having a lower fundamental and a more accurately known spectrum than the vocal cord tone. A few measurements are reported, obtained by means of an artificial larynx at 30 pulses/sec, applied to the outside of the throat wall. Analysis is made from a tape loop, by means of a narrow band wave analyzer. The results are not wholly satisfactory because the spectrum inside the tract is not accurately known.