Hz. just refers to the periodicity of an event being repeated x amount
of times per second. In this case we are talking about a note (snare hit
for instance) being played on every beat at 357 bpm, or 5.95 bps. We can
say that the frequency of the snare hits is 5.95 Hz. Of course, we can
hear the snare hits; what I was referring to when talking about the
'audio range' was the threshold at which the brain ceases to recognize
events as being distinct from one another, and melds them together. If
we are talking about sound, this is called the audio range (20Hz. - 20
KHz) If we had, say the purest of waveforms, which has no partials, the
sine wave, we would not be able to hear it at a freq. lower than aprox.
20 Hz. We can hear it's effects on an audio signal if it is used to
modulate one, this is a common device used in many different synthesis
methods. The snare hits in question make up a very complex waveform,
consisting of a lot of noise. Many frequencies are represented, and at
various amplitudes as the sound develops. It would make sense (although
it is by no means the only way to look at the waveform) to look at the
period of the waveform as the onset point of the sound (snare hit) to
the onset point of the next hit. In this case the fundamental freq. of
the waveform would be 5.95 Hz. If we were to speed up the freq., past
20Hz the fundamental will creep into audio range, and you will hear a
'new' note. The individual snare hits can be compared to frames in a
film, the pictures cease to be interpreted as discreet events at more
than 20Hz or so, and take on a fluid continuos motion. I agree with you
that 5.95 bps is not that big a deal hence: "I'm sure many a Jazz
drummer does 357 or more on the snare, although I've never counted." . I
hope I have been able to make my point clearer.
Regards,
Christophe
Andrei wrote:
I don't quite follow your logic here. I don't see what the bps (tempo)
has to do with
audible frequencies. 5.95 bps doesn't equal 5Hz. 5.95 beats per second
is not that
big of a deal. That's about the rate of triplet 8th notes at the very
average tempo
of 120 BPM.
C McKeon wrote:
357 bpm/60 = 5.95 bps. This is still way in the sub-audio range. You
would have to effectively almost quadruple the figure in order to get
into the audio range of 20-23 Hz. (Depending on the human), i.e. a drum
sample or repetitive sound would have to have a frequency of 20Hz-23Hz
(Or 1200-1380 bpm) in
order to be heard as a single tone. I'm sure many a Jazz drummer does
357 or more on the snare, although I've never counted.
Regards,
Christophe
P.S. Interestingly enough the figure of 20-23 Hz seems to be the
breakpoint where the brain ceases to differentiate between singular
events and 'chooses' to amalgamate them. This is why movie frames must
be shown at, or faster than this Freq. Experiments with touch have even
been devised where an equal
pressure applied to the skin at less than 23Hz are perceived as being
separate events. While at higher frequencies they are perceived as a
constant pressure, as though there were no movement at all. A snails
perceptual freq. runs at about 4 Hz. No joke.