[Don Pearce[_3_]]

On Tue, 24 Jan 2012 16:44:45 GMT, (Don Pearce) wrote:

On Tue, 24 Jan 2012 17:33:29 +0100, Mxsmanic
wrote:

What does it mean when the waveform of a sound is essentially symmetrical,
except that the positive excursions of the wave are bigger than the negative
excursions, so that it looks a bit lopsided?

And what does it mean when a wave form looks as though it has been raised or
lowered as a whole, so that what would have been the zero crossings are now
above or below zero?

I've seen both occasionally but I haven't been able to determine what
circumstances cause them.

Someone here said something about trombones not producing symmetrical
waveforms, which reminded me of these anomalies. How or why would a particular
instrument produce a waveform that isn't symmetrical around zero?

That's just how waveforms are. You can, if you fancy whiling away a
few hours, think about maybe the way reeds work, or the embouchure on
a mouthpiece but none of that will really get you very far.
It's just how real life is.

d

I meant to add. The presence of even order harmonics guarantees
asymmetry in the waveform.

d