summation tones and sine tones

>>So, I had to try to tune the dyads with the volume real low, and then we
>>would try to check by turning up the volume and listening for beating.
>>This procedure wasn't conclusive, but again I did well, thanks to sum
>>tones, which is what I listen to when I tune pianos (which I should stop
>>doing, since it turns out horrible tunings).
>
>I don't know what you mean about summation tones. But anyway, what if you
>try tuning only the melodic interval, as I suggested?

What do you mean you don't know what I mean? The whole thread is about it.
You just explained it to Darren.

I actually don't know if they were sum tones. They sounded like high
frequency pure tones, and had the same ghosty "strafing" effect that
difference tones have when you turn your head.

I don't actually have the gear to do the test you recommend. I don't have
a tuning knob on any synth, and Malinowski's generators are both-at-once or
nothing-at-all (also, the box is several thousand miles away). Also, I'd
like to note for the record that this test is not equivalent to telling two
tunings (with up to 50 cent differences) of a melody apart, which is the
thing I said would be easy. Actually, considering how little "up to 50
cent differences" does to specify a method of re-tuning, I retract my
statment.

>What tunings were you tuning with sum tones, and why are they horrible?

Ah- I was talking about the unisons. For some reason, the sum tones (or
whatever it is that I hear) don't always stop beating when the fundamentals
do, and vice versa. Can that be right? Ed?

-C.

>>I don't know what you mean about summation tones. But anyway, what if you
>>try tuning only the melodic interval, as I suggested?

>What do you mean you don't know what I mean? The whole thread is about it.
>You just explained it to Darren.

I meant I don't know what you mean about sum tones being audible at low
volumes and yielding bad tunings on a piano. Summation tones are actually
(this is not well understood) much more difficult to produce in the human
auditory system than difference tones.

>Ah- I was talking about the unisons. For some reason, the sum tones (or
>whatever it is that I hear) don't always stop beating when the fundamentals
>do, and vice versa. Can that be right? Ed?

Difference tones would make some sense in this context. Since the piano's
partials are slightly inharmonic, their difference tones would beat with the
fundamental and with other partials.

>>Ah- I was talking about the unisons. For some reason, the sum tones (or
>>whatever it is that I hear) don't always stop beating when the fundamentals
>>do, and vice versa. Can that be right? Ed?
>
>Difference tones would make some sense in this context. Since the piano's
>partials are slightly inharmonic, their difference tones would beat with the
>fundamental and with other partials.

The stuff I hear is much higher in pitch than the notes sounding, so it
couldn't be difference tones. Maybe I'm listening to partials.

-C.

>>>Ah- I was talking about the unisons. For some reason, the sum tones (or
>>>whatever it is that I hear) don't always stop beating when the
fundamentals
>>>do, and vice versa. Can that be right? Ed?
>
>>Difference tones would make some sense in this context. Since the piano's
>>partials are slightly inharmonic, their difference tones would beat with
the
>>fundamental and with other partials.

>The stuff I hear is much higher in pitch than the notes sounding, so it
>couldn't be difference tones. Maybe I'm listening to partials.

Well, two piano strings that are supposed to be in unison should have the
same inharmonic partials. Is the phenomenon different with two strings than
with one string? If so, you probably have a defective string and/or piano
that's causing different degrees of inharmonicity on the two strings. Then
of course the partials will beat when the fundamentals don't, and vice
versa. The people on the pianotech list can probably tell you more about
what kind of pianos are particularly prone to unpredictable inharmonicity,
but this is a well-known phenomenon (even in a few Steinways) and is quite
mysterious theoretically.