Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!nrl-cmf!ames!ll-xn!mit-eddie!bloom-beacon!gatech!emcard!mat
From: mat@emcard.UUCP (Mat Waites)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Is 29 Khz really the fastest audio playback rate?
Message-ID: <5499@emcard.UUCP>
Date: 17 May 88 15:28:08 GMT
References: <1991@sugar.UUCP> <4113@killer.UUCP>
Reply-To: mat@emcard.UUCP (Mat Waites)
Organization: Emory University Cardiac Data Bank
Lines: 39

In article <4113@killer.UUCP> elg@killer.UUCP (Eric Green) writes:
>in article <1991@sugar.UUCP>, karl@sugar.UUCP (Karl Lehenbauer) says:
>> The Amiga Hardware Reference Manual says that 29 KHz is the maximum
>> playback rate for audio samples.  Is this for sure true and are there
>> any sorts of software-achievable hacks to exceed it?
>
>1) Most good-quality stereos give up the ghost somewhere around 20khz. 
[...]
>2) Most adult's ears give up around 17-18khz (for someone with VERY good
[...]
>
>Sorry, but I think this is a non-problem.
>
>--
>    Eric Lee Green                     {cuae2,ihnp4}!killer!elg


BUT, you have to sample at a significantly greater rate than the frequency
you are trying to reproduce. Don't cd players sample at 64khz or something
like that just to get good reproduction at 20khz?

I think the rule of thumb is that the minimum sampling rate is twice the
frequency you are trying to reproduce; 29khz sampling will only return
a clean sound for sounds below 14.5khz by that rule.

14.5 is still pretty good unless you are trying for hi-fi. The higher
frequencies are not necessarily needed for actual tones in the music, but
for maintaining the ambience or spatial quality of the music. And even
old folks who can't "hear" a pure 18khz tone can tell the difference between
music that has the highs filtered out, and music that doesn't.


mat


-- 
  W Mat Waites                     |  PHONE:  (404) 727-7197
  Emory Univ Cardiac Data Bank     |  UUCP:   ...!gatech!emcard!mat
  Atlanta, GA 30322                |