Re: Real Instruments Sound Better
By Robbie Rhodes
Subscriber <Linnstaedt@aol.com> sent me this note:
> Dear Robbie, thanks for your very informative article.
>
> > This is equivalent to attaching the high-frequency tweeter to the
> > _cone_ of the woofer, and the result is that the high-frequency sine
> > wave is frequency modulated by the low-frequency motion of the woofer.
> > It's a simple Doppler effect."
>
> In all of this, I am puzzled that we don't experience IM distortion
> in our hearing. Each ear uses a single diaphragm (eardrum) which
> transmits its vibrations via bones of the inner ear. Seems that
> the mass of the moving bones should create their own distortion
> through the effects of inertia. Would love to study this situation
> more. What are your thoughts?
You're quite right, the ear itself does create distortion. When you ride the Merry-Go-Round horse past the real, _live_ WurliTzer 150 or 165 band organ, the sound is quite loud, unpleasantly so. But at a greater distance it's jolly and exciting and a pleasure to hear. I don't know the exact mechanisms, but the ear gets more-and-more non-linear as the sound level gets greater, and that generates harmonic distortion products and intermodulation distortion.
Incidentally, for years hi-fi audio amplifiers for years have touted their ever-lower distortion specifications for Total Harmonic Distortion (%THD) and Intermodulation Distortion (IMD). But manufacturers seldom mention loudspeaker distortion characteristics. They're too ashamed!
-- Robbie Rhodes |
(Message sent Thu 23 Nov 1995, 05:18:19 GMT, from time zone GMT-0800.) |
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