The Fourcin laryngograph handily provides a voltage output, lx, proportional to the area of the glottal opening. We have investigated the uses of the lx signal in the voice studio as a feedback modality in parallel with the usual kinesthetic, aural, and interpersonal cues by which a singer manages his voice. The lx signal is returned in four ways: (1) The lx waveform, normalized in amplitude and frequency, is displayed on an oscilloscope. The mechanics of phonation are immediately evident in this display. A kinesthetic connection with the visual pattern develops easily as the singer explores the variation of his waveform with pitch or loudness. (2) The power spectrum |Lx′| of the time derivative of lx, is displayed in real time above a keyboard mnemonic. A singer tends to “feel” the waveform lx, including its evident phase relationships, while he “hears” the power spectrum | Lx′|, which is identical to that of the glottal acoustic source. (3) Laryngeal behavior over an extended time is notated as a real time soundscore. Techniques 2 and 3 are applied to the voiced sound as well [see J. Acoust. Soc. Am. Suppl. 1 66, S42 (Fall 1979)]. Feedback modality 4, the laryngeal envelope, surrounds the singer with the amplified sound of his own lx′, which, above a critical loudness level, obliterates normal auditory cues, placing the singer in a new and pedagogically useful relationship with his own voice.
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