[Harp-L] Re: Harp-L Digest, Vol 19, Issue 27

[David Priestley <drmidnight@xxxxxxxxxxxxxx>]

On 15 Mar 2005, at 18:30, harp-l-request@xxxxxxxxxx wrote:
> I'm sure someone will correct me if I'm wrong, but its my 
> understanding that with a Just Intoned
> harp, the barely audible difference tones will sound in tune and 
> pleasing to the ear, but with an
> equal temperament harp the difference tones will sound harsh and not 
> so pleasing.

The math for difference tones is thus: when two pitches sound at the 
same time they create a third sound / pitch , which is called  'the  
difference tone"

the pitch of the difference tone can be worked out thus. Take the lower 
frequency away from the higher and what ever you are left with is the 
pitch of the difference tone at that time. Example: tongue block A=440 
Htz and its octave A = 880 Htz. Subtract 440 from 880 and you get 440, 
in that instance you get a pleasing fat bottom end. This is partly why 
the tongue blockin' urban style has such a fat sound. How ever, a small 
look at the difference tone possibilities, no matter what your 
intonation is , will show that you have more oppertunity for disonance 
than consonance.

Playing acousticaly the ear will most litely miss the diference tones, 
in the same way as it misses the harmonic sequence - but put it down a 
mic and the system can't tell the difference 'twixed the carrier wave 
and other parts of the sonic signature, so they all get loud togeather. 
Try out this sort of stuff with headphones on before you put it to an 
audence if you're worried about it.