[Harp-L] Re: Ghost Notes and Equal Temperament

[Jonathan Ross <jross38@xxxxxxxxxxx>]

> used to describe them, as all have their uses--people like Jimmy
> Reed, John Lee Williamson and others didn't seem to have any problem
> getting "fat", "deep" or "sweet" sounds playing adjacent intervals.
> But that is more a style debate, and has little to do with the
> generation of difference tones and how they work.
>
> Point well taken, but i don't think those old masters played ET harps.

Good point.  I'll use Richard Hunter as an example then.  Or better  
yet, this is a great reason not to play 12TET diatonic harmonicas.

> But, since you have a more sophisticated knowledge of this stuff  
> than i do, can you tell me A) if the measurable dissonance of the  
> difference tones is LESS for notes played on non adjacent holes on  
> ET harps (as compared to notes played on adjacent holes), and B) if  
> the  degree of dissonance has any relationship to how far apart the  
> non adjacent notes are from each other?  i suspect that that the  
> larger the interval, the less dissonant the difference tones would  
> be.  but i don't really know, so i'm asking.

The degree of dissonance is controlled not by how far apart the notes  
are on the harmonica but rather by what the relationship between the  
two notes is.  Major thirds in 12TET are more dissonant than fifths.   
But, they do not become significantly less dissonant if it's a major  
third or a major tenth--(ie, a 1-2 blow interval and a 1-5 blow  
split).  The physical distance of the notes on the harmonica is  
unimportant--it is the tonal distance between each note that  
determines the difference note pitch.

12TET favors certain intervals over others, so the difference tones  
created by fifths and fourths will be less harsh than those created  
by thirds and sixths, for instance.  In 12TET, playing 1 and 3 blow  
together will have fewer beats than playing 3 and 4 blow (and the  
difference tones will reflect this), but that is not because these  
are splits and adjacent notes, but more because fifths beat more  
slowly in 12TET than fourths.  And both of these will have fewer  
beats and less dissonant difference tones than when you play 2 and 4  
blow (a minor sixth).

> Some of what you have already told me is consistent with my  
> uneducated (I'm self taught)  suspicion: You say that  the adjacent  
> intervals on a harmonica are generally a third apart and the  
> presence of a major third creates significantly dissonant  
> difference tones.  Okay, does that mean that when the interval is  
> greater than a major third, there will be less dissonance and the  
> wider the interval the less dissonant the difference tones will be?

No.  It depends on how far the 12TET interval is from a beatless  
interval.  The fourth and fifth are pretty close to their beatless  
intervals in 12TET, while thirds (smaller) and sixths (larger) are  
farther and thus have more pronounced beating or "out-of-tune"  
sensation.



>

 ()()    JR "Bulldogge" Ross
()  ()
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