Seminar at Speech, Music and Hearing:
Observations on the EGG spectrum slope under various phonatory conditions
Angela Libeaux, RWTH Aachen
Opponent: Nils Efraimsson
AbstractElectroglottography (EGG) measures instantaneous vocal-fold contact area and is thus sensitive to the speed of contacting and opening. It is easy to acquire, and, lacking the superimposed vocal tract resonances, its spectral envelope is much simpler than that of the airborne signal. Although the signal is not acoustic, one might expect that some of the variation in the spectral tilt of the airborne signal be present also in the EGG. Wideband spectra of EGG signals from sustained phonation were examined under various conditions, including changes of electrode position, vowel, subglottal pressure and SPL. Recordings were made of subjects producing /pV/ utterances with simultaneous acquisition of EGG and intraoral pressure. The EGG spectrum effects of vowel changes were small. The EGG spectrum envelope was found to be quite linear in dB/octave, from harmonics 2 to 10, and often much higher. EGG spectrum slope change with SPL was generally greater in soft phonation than in loud phonation. Additionally, recordings from an existing database, of 8 trained male singers with audio and EGG, were analysed for EGG spectrum variation with SPL. The singers performed crescendo tasks on sustained tones, with a typical SPL variation of up to 20 dB from soft to loud. Fitting straight lines to wideband EGG spectra yielded slopes of -14 to ‑9 dB/octave. The slope variation was small but in most cases positively correlated with overall SPL in the range 75-95 dB at 0.3 m. Also, there was in some cases a pronounced ripple in the EGG spectrum, due to double peaks in the time derivative of the closing EGG waveform.
15:15 - 17:00
Friday September 10, 2010
The seminar is held in Fantum.
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