If you have ever been a house music fan or a clubbing-freak, you are
already very familiar with the "beats" here discussed, for you have
banged your head a lot at these rates (i.e. 450,500,550 and 600ms).
Check BPM charts online and you'll notice that about 75% of the entries
refer to beats between 380 and 620ms (i.e. roughly between 160 and 100
BPM).
(Before going further, I must acknowledge the fact that for this
and the following blog-entries I relied on information gathered from:
Leon van
Noorden & Dirk Moelants (authors), Resonance in Perception of Musical Pulse, Journal of New Music Research, 28, March 1999, Swets & Zeitlinger Publishers, The Netherlands, pag. 43-66.) Getting to discriminate and memorize these four isotempi is really
hard. I "live" with them since long but I still mistake one for another once in a
while. To make things worse, I was unable to devise any tricks (like
the legatissiomo performance for IOIs from 200 to 350ms or like the
zig-zag test for IOIs around 400-450ms).
If you have a friend who is a professional DJ and if he/she happens to
be able to tell these beat-rates by heart, ask him/her how he/she
managed to acquire this competence – and pass this information to me as well!
A good training exercise for these paces (and others as well) is to add
to your iTunes application an extension called "iTunes-BPM"
and
start guessing IOI values. The application is free and you may download
it here.
As it only displays BPM values and not millisecond-measured IOIs, keep
at hand a conversion-list (i.e. BPM to millisecond). Make it as comprehensive as
possible: that is, convert to milliseconds all BPM values from 30 to
1200, although you'll probably never have to refer to such extreme
values. This way, in time, you will start recognizing IOI values that
fall in between our 50ms purely conventional grid (e.g. an IOI that seem to you
as being close neither to 500ms nor to 550ms, but a middle value).