[Harp-L] Semitones Cents and what not.

[Aongus Mac Cana]

I don't know why I have become so hung up on this stuff, because it is not
going to contribute one whit to my inadequate playing skills. Maybe it is
because an engineering background gives you a guilt trip whenever you don't
understand how something works.

What is a semitone? Is a musical scale a geometric progression where each
step represents a percentage increase or decrease on the frequency in Hz of
the note you start with? I have been told that the octave of every note is
twice the frequency of the note in question. Consequently if A4 is 440Hz A5
must be 880Hz A6 1760Hz and so on ad infinitum. This becomes very handy when
you are trying to learn a tune, because if you reduce a tune to half speed
on media player it is still in the same key - just an octave lower. Before
computers became all the go, we used to be recommended to use those
dictating machines that could be played back at half speed as musical
teaching aids.

What bothers me is that a semitone cannot therefore be expressed as a simple
frequency difference. The higher you go up on the harmonica or a keyboard
the bigger the frequency difference between one note and the next. Then what
about these Cents that the "experts" throw about with such abandon? As in:
"I tune all reeds a few cents high to allow for the fact that they will go a
bit flat when actually played". Can Cents be expressed in Hz higher or Hz
lower?

As for harmonics - let's not go there. What instrument produces the purest
tones unpolluted by harmonics? Pan pipes? Synthesiser perhaps?

Beannachtai

Aongus Mac Cana