John F. Sowa wrote:
> Jeff et al.,
> I can believe that one can hear a bar of silence in contrast
> to music. That is comparable to "seeing" a hole in a solid
> bar. But if you remove the surrounding sound or solid, the
> contrast vanishes. Therefore, the contrasting hole or
> silence could not be perceived. (01)
Not sure what you are saying here. If you suggest that silence is a
component of music, then you are right. It cannot, however, replace the
entire performance. It is an architectonic portion that composers or
performers manipulate for an artistic effect. For that matter, sound is
used as a sort of picture frame at the beginning and end of a piece to
delineate when the piece starts and ends.
> > In Wichita, the hall reverberates a quarter tone low.
> I find that hard to believe. There are several ways of
> distorting sound, either electronically or mechanically:
> 1. Shift the phase of the sound wave (i.e. delaying it
> by means of an echo or a short-term storage mechanism).
> 2. Amplifying or damping some frequencies more or less
> than others.
> 3. Creating overtones that are some integral multiple
> or submultiple of the incoming sounds.
> But a shift of a frequency, even a quarter tone, is
> *extremely* difficult to do without very sophisticated
> equipment. I do not believe that any music hall could
> accomplish that transformation by ordinary acoustic means. (02)
It is an example of inadequate design, and is quite easy to achieve.
Consider that the hall consists of an audience chamber and a stage
house. The chamber is quite high with reflective walls. Sound,
especially from high-pitched instruments, ascends into the upper stage
house and into the hall. In a hall 120 feet deep, sounds would only need
to be deflected a couple of feet (at 440Hz) when bouncing off the walls
to hear a doppler shift of a quarter tone.
> For example, suppose the incoming frequency f was X Hertz and
> the outgoing frequency was X-y Hertz. That would imply that
> y vibrations per second were somehow "lost"
> or, even worse, "stored" for future transmission.
> That is an extremely complicated nonlinear transformation.
> You could accomplish it by recording the sound and later
> playing it back with a slower turntable or the equivalent in
> electronics. But I don't believe a typical music hall could do that. (03)
In fact, they do. So does "echo point" in the mountains, where the
sender often hears the reflected sound a bit lower. (04)
-- Jeff Schiffel (06)
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