Re: vibrato (Jont Allen )

Subject: Re: vibrato
From:    Jont Allen  <jba(at)RESEARCH.ATT.COM>
Date:    Fri, 10 Apr 1998 18:39:52 -0400

Laurent Demany wrote: > > Seashore's observation has been verified for very small, and rather rapid, > vibratos: It is impossible to discriminate a just-detectable sinusoidal FM > from a just-detectable sinusoidal AM if the modulation rate exceeds about 5 > Hz. But the discrimination is possible is the modulation rate is about 2 Hz. > See: > > > Laurent Demany Back in the old days, following the first measurements of the pure tone frequency JND by Shower and Biddulph (JASA 1931), Fletcher integrated the JND to recover the place-frequency map. He found the same map as obtained by the integration of the critical ratio data, except the frequency JND data was shifted by about 1/2 octave. He also showed that the frequency JND was equal to 1/20 of the critical band. He concluded that you do the freq. JND based on the high-freqency slope, as amplitude discrimination detection. This is clearly the story above a few kHz, as if you rove the intensity, the freq. JND seriously degrades (Moore). At low frequencies it would be possible to use the phase-locked signal to estimate the pitch. I think the data suggested that this might be the case below a few hundred Hz. I am not sure about these details however. Perhaps someone could fill us in on these. This is described on page 169-175, and page 150-152 of his 1950 book. (You can buy it from ASA for < $50, which is a bargain. Sorry for the small ad.) 1) How do people view this result today? 2) This story seems to be in agreement with the above observation described by Laurent. -- Jont B. Allen, Room E161 AT&T Labs-Research 180 Park AV. Florham Park NJ 07932 973/360-8545voice, x8092fax

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