To: "VOCALIST" <vocalist>
Subject: Re: the Physics of Music
Date sent: Tue, 18 Jan 2000 21:43:43 -0500
Send reply to: VOCALIST <vocalist>


-----Original Message-----
From: David Menzies
To: vocalist <vocalist>
Date: Tuesday, January 18, 2000 8:29 PM
Subject: Re: the Physics of Music


>Jenni writes
>"In a class in the physics of music, my professor (who is not too familiar
>>with Western Music being from India) insists that vibrato of all types is
>>made and artificial. >>Does anyone who has more of a science background
than I have any ideas as
>>to how I could make him see the musicians' side of things?


Jenni,

According to Vennard, a study conducted by Mason and Zemlin reveals that
intermitent innervation signals to the crycothyroid muscles (responsible
for pitch) is the cause for vibrato as quantified in electromyographic
analysis.
In other words, the bioelectrical signal from the brain which causes the
cryco-thyroid to stretch the vocal cords for pitch is not one (1) continuous
signal which maintain a rigidly stable cord length. Instead the muscle
behaves like other skeletal muscles and has a "twitch" period which includes
precontraction, contraction and relaxation. It would be logical that there
would be pitch variants during the relaxation phase of the twitch. The
innervation of the crico-thyroid under electromyographic analysis suggests
between six and seven stimuli per second which coincides with the rate of a
normal vibrato.

A wobble on the other hand occurs when muscles of the larynx (both intrinsic
and extrinsic) are put under such stress as to become tired. In such a
state, like a stretched-out arm tired of holding a heavy weight, the
mechanism or parts of it begin to tremble. That tremble is super-imposed by
hyper-activity in several of the muscles of the mechanism. Wobbles, in my
experience, can be reversed, but often require lots of time for muscular
retraining and recoordination. Feel free to pass this information to your
scientifically minded physics teacher.

If he requires the sources for this information, suggest: Vennard. Singing:
The Mechanism and the Technic (Par. 694-720).
Also Powers, Scott. Exercise Physiology: Theory and Application to Fitness
and Performance (Chapter 8).

I'm sure Miller and others deal with the subject.

I hope this helps.

JRL.