jms@tardis.Tymnet.COM (Joe Smith) (01/13/91)
I was wandering around a the MacWorld Expo today, checking out the new
products. One thing that struck me was that most of the digitized
audio output did not have a low-pass filter, and it sounded awful.
Imagine an audio distorter that, whenever it detects a 2000 Hz tone,
it adds a 6000 Hz tone. And when it detects a 1000 Hz tone, it
adds a 7000 Hz tone. (When the main sound has a descending pitch,
the distortion has a rising pitch.) When human speech is passed
through such a distorter, it produces an awful high pitched rattle.
The above description is exactly what happens when an audio sample
is digitized at 8000 Hz, and played back on a system that does not
have a low-pass filter to get rid of the aliasing due to heterodyning.
My point is: Be thankful that the Amiga has a low-pass filter on the audio
outputs as standard equipment. At medium and low sampling rates, its
presence causes a noticable improvement in audio quality.
--
Joe Smith (408)922-6220 | SMTP: jms@tardis.tymnet.com or jms@gemini.tymnet.com
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San Jose, CA 95161-9019 | humorous dislaimer: "My Amiga 3000 speaks for me."