Path: utzoo!utgpu!news-server.csri.toronto.edu!clyde.concordia.ca!uunet!mitel!sce!cognos!geovision!gh
From: gh@geovision.uucp (George Hagilaris)
Newsgroups: comp.sys.amiga
Subject: Sampling Audio (was Re: Future of Amiga)
Message-ID: <875@geovision.UUCP>
Date: 16 May 90 19:25:07 GMT
References: <2363@ucqais.uc.edu> <10176@mentor.cc.purdue.edu> <2873@darkstar.ucsc.edu> <1990Apr29.231644.11461@uunet!unhd> <10232@batcomputer.tn.cornell.edu> <29700@ut-emx.UUCP> <10233@batcomputer.tn.cornell.edu> <4848@daffy.cs.wisc.edu>
Reply-To: gh@geovision.UUCP (George Hagilaris)
Organization: GeoVision Corp, Ottawa, Canada
Lines: 21

In article <4848@daffy.cs.wisc.edu> pochron@cat25.cs.wisc.edu (David Pochron) writes:
 [stuff deleted]
>Sound frequency is measured in hertz or Khz, but the rate at
>which the chips can output data to the DAC is in SPS.  The Amiga can do 28K SPS
>which means the highest frequency it can play is 14 Khz.
>CD players are at 41.???K SPS and they have a freq. response of about 20 Khz.
>   (just right for human ears)

28K SPS does not mean that the _highest_ frequency the Amiga can play is 14KHz.
A sampling rate of 28KHz (ie. 2*14KHz), or 28K SPS (same thing), is the
sampling rate required to accurately reproduce a 14KHz tone (this includes
harmonics as well).  You can still _play_ a sound which is greater than 14KHz,
but if you are only using a 28KHz sampling rate (28K SPS), then you will not
get a "faithful" reproduction of that sound.  The rule is that you sample at
(at least) twice the frequency of the _highest_ frequency harmonic of the sound
you are sampling.  A sampling frequency of 40KHz is enough because (hardly any)
people can hear sounds/harmonics/tones above 20KHz.

--
George Hagilaris
uunet!geovision!rock!gh