Re: [tuning] Digest Number 1478

Hi Jeff,

> I haven't ever tried it from this angle and I must
> admit I was very surprised you were able to get the
> results you did doing what you are doing now, which I
> would havwe said would not work that good.

I was very surprised too actually.

However what seems to be happening is that even if the
second or higher harmonics are more prominent, the
first harmonic still shifts the other peaks
enough so that one can recognise the pattern by
just looking for the wave crossings and ignoring
secondary peaks.

E.g. peaks for second harmonic will be reinforced
by the first harmonic for one wave, then for the
next wave they are out of phase and so rather than
reinforced, are counteracted. So the peaks
are prominent on the oscilloscope.

Any wave one can recognise on the oscilloscope
by it's prominent highest peak could in principle
be found this way, and then the pitch figured
by wave crossings.

As you see from the ex. clips, even works if
you have some reasonably quiet background music
with a main singer / instrumentalist (if timbre is suitable).

> Sorry I can't be of help here but it looks to me like
> you're the current expert in this field.

I suppose perhaps I am ;-), by default of being the only
one I know of working on it at all - I've done web search
and can't find anything yet on anyone else using a wave
crossing technique for pitch detection.

Anyone heard of such a thing before?

Robert