RE: [tuning]

could some one explain hoe to work out theese ratio's

im struggling away and not quite sure how to work them out ie octave 2:1

etc

thanks

rob>

>

--------------------------------------------------------------------------------

Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com
[http://www.hotmail.com].

>could some one explain hoe to work out theese ratio's

>im struggling away and not quite sure how to work them out ie octave 2:1

Hi Robert!

You may be asking several different things, so I'll attempt to address them below.

The ratios we're referring to are frequency ratios. For example, the note A is 440 Hz (cycles per
second), and the note A' an octave higher is 880 Hz. The ratio is 880:440 or 2:1. All octaves
have ratio 2:1.

If you know an interval is x equal-tempered semitones, the formula for getting the ratio of the
interval is

ratio = 2^(x/12).

Conversely, if you know an interval has ratio r, and you want to know how many
equal-tempered semitones it is, the formula is

ET semitones = log(r)/log(2)*12

Hope this helps . . .

Robert Greco wrote:
> >could some one explain hoe to work out theese ratio's
>
> >im struggling away and not quite sure how to work them out ie
octave 2:1

Hi Robert,

Our apologies for the disturbing meta-posts on the list. Just try to
ignore them. You will have noticed that despite being a professional
musician and high powered mathematician Paul still has time to help a
newbie with the basics.

Sorry if I'm assuming too little knowledge on your part, but I'm not
sure how _anyone_ could "work out" that an octave was a 1:2 frequency
ratio. Either it is defined as such, or someone measured them aeons
ago and found that they always were close.

Anyhow, these might help.

The introduction only of
http://dkeenan.com/Music/DistributingCommas.htm

This spreadsheet calculator
http://dkeenan.com/Music/CentsToRatios.xls

The background only of
http://dkeenan.com/Music/EqualTemperedMusicalScales.htm

Regards,
-- Dave Keenan