Sine and square waves percieved pitch, why?

[janneman]

Originally posted by KBK
[snip] The human voice is single-sided, as in the fact that the entire human voice is a positive pressure front, [snip]

Ahhh!. That must be the reason that the world pressure rises and rises with all that talking! So much hot air, maybe we found the real source of global warming!

Jan Didden

[sam9]

Is this related to why lossey compression works even if it offends my sense or order? I'm thinking of masking where a sharp loud shound will mask what follows for a few mS. MP3 uses this and I think DTS may as well. Would this period where masking occurs be analogous to the recovery periode of a diode?

[baggystevo82]

Isn't that where a muscle tightens up in your ear in response to a loud sound to stop it vibrating too far and too violently? I remember a surgeon on Tomorrows World tested to see if this ear implant thingy worked by stimulating it and seeing if that muscle tightened up.
Steve

[sam9]

Thet example I can cite is why "click and pop removers" from the days of vinyl were/are often unsatisfactory. I had one way back when and while it worked sometimes, sometimes it just turned a loud pop into a dull thump. What was wierdwas that years later software inteded to do the same thing to for LPs trancfered to CD would sometimes display the same behavior. This hints that it is not the pop-removal that is the problem.

Using software that let me zoom in to the actual wave form revealed what was happening. First the pop was bing removed and no artifacts added. What was going on was that the pop was followed by dampened ringing. This turned out to have nothing to do with the LP either since it could be reduced but not eliminated by using a different stylus. The thump was there alol along but the initial pop masked it. remove the pop and the tump/ringing was revealed. You could sometimes get rid of the thump, too by lowering the threashold of the remover (hardware or software type).

Anyway the point is that I'm completely convinced of the reality of the masking effect of an initial stong inpulse because of my experienxe tracking down "thumps".

[Sch3mat1c]

Of course... mind you... that would suggest that voices would sound "upside-down" if I played them 180 degrees out of phase (i.e., reversed terminals). They do not.

Explain?

Tim

[baggystevo82]

I guess what was being talked about earlier just means that ears are more responsive to compressions than rarefactions? Wouldn't that just mean that the ear was non-linear in response relative to drum excursion or air pressure on the drum? That being the case I cant think of an explanation, unless it's something to do with it being a longitudinal wave....dunno...
Steve

[dnsey]

Looking at it in a simpler way (within my understanding!), it seems clear that below the 'crossover' point, the square wave frequency approximates f/2 within experimental error. (Note the part of the question referring to ratio). It therefore seems likely that the first harmonic of the sq wave is more easily perceived than the fundemental frequency. At the crossover point, the ear/brain begins to perceive the fundemental directly. Is this not due simply to the ear's non-linear frequency response - i.e. more LF enregy than HF is required to perceive a particular (subjective) amplitude?
Apologies if this amounts to what's already been said, but my simplistic mind sees it more easily that way:-)
I'd also note that both generators should be set to produce the same output, as perceived pitch varies with amplitude, and this might muddy the waters. I would be interested to know if the crossover point also changes with amplitude, or indeed with individual listeners.

[baggystevo82]

yes that was what I was thinking, that at low frequencies the ear/brain can percieve the seperate up and down parts of the wave (which occur at a rate of 2f) and then at higher frequencies the ear/brain loses that ability and sees the overall shape, rather than the seperate transients...if that makes sense. I still have a bit of a problem with the suddenness of it though, I certainly would be interested in other peoples observations on this! If anyone wants to give it a go, I used the attatched signal generator (opening 2 instances at the same time). I used 0dB gain for the sine wave, and -20dB for the square for reference.
Cheers,
Steve

[sam9]

Express the transition point as a wave length rather than frequency. Then consider if the wave length (or half or quarter wave) corresponds to any typical human dimension shuch distance between ears, length/radius of auditory canals or other hearing structures.

I'm just taking a shot in the dark (i.e., this is not one of those exersizes where I already know the answer), but virtually all wave behavior has some relationship to the physical dimension of the objects with which it interacts.

[Mr Evil]

Originally posted by baggystevo82
yes that was what I was thinking, that at low frequencies the ear/brain can percieve the seperate up and down parts of the wave (which occur at a rate of 2f) and then at higher frequencies the ear/brain loses that ability and sees the overall shape, rather than the seperate transients...

If that is so, then you can test it by performing the experiment on people with different hearing bandwidths (i.e. people of varying ages). If the transition frequency shows no correlation to age, then the theory is false.