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From: robert bristow-johnson on 6 May 2008 20:04
On May 6, 5:04 pm, Jerry Avins <j...(a)ieee.org> wrote:
> Scott Hemphill wrote:
> > glen herrmannsfeldt <g...(a)ugcs.caltech.edu> writes:
>
> >> Jerry Avins wrote:
> >> (snip)
>
> >>> 44.1/2=22.05 KHz, the maximum possible frequency that can be
> >>> reproduced according to simpleminded theory. 19 KHz is closer to the
> >>> practical limit. A few humans can hear frequencies higher than that,
> >>> so the answer must be no. It is sufficiently high to exceed the
> >>> hearing limits of almost all adults.
> >> So CDs for babies might run into the limit, but not for adults.
>
> >> This reminds me of a story about kids loading ringtones into
> >> cell phones that their teachers can't hear. What is the sample
> >> rate for cell phone ring tones?
>
> > This link is supposed to be such a sample. It's at 32kHz mono.
>
> >http://audio.cbsnews.com/2006/06/12/audio1701350.mp3
>
> > Scott
>
> I didn't hear a thing. :-) (Neither did my school-teacher son.)

then i guess the scheme works pretty good. (keep them school-teacher
sons in the dark.)

BTW, i couldn't hear anything either. but i didn't look at it on a
scope.

r b-j
From: Green Xenon [Radium] on 5 May 2008 23:21
rickman wrote:


> On May 4, 2:18 am, "Green Xenon [Radium]" <gluceg...(a)excite.com>
> wrote:
>> SteveSmith wrote:
>>> One of the common arguments used to justify these higher sampling rates is
>>> nonlinear effects, both in the ear/brain and loudspeaker systems. Here's
>>> one version:
>>> http://www.digitalaudio.dk/technical_papers/aid.pdf
>>> Keep in mind that audio manufacturers don't just design their equipment to
>>> meet engineering specs-- they design their equipment for what people will
>>> buy. There is even still a market for tube-based amplifiers, because some
>>> people believe that transistors don't reproduce the sound as well.
>>> Regards,
>>> Steve
>> The site discusses sample rates up to 96 kHz. I understand it is totally
>> logical to use a 96 kHz sample rate for certain audio applications.
>> However, the site does not discuss why DVD-audio [in stereo 2-channel]
>> uses a 192 kHz sample-rate. Nor do I see any rationality in using 192 kHz.
>>
>> DVD-audio uses a sample-rate of 96 kHz when using the 5.1 channel mode.
>> However when in stereo -- i.e. 2-channel -- mode, the DVD-audio uses a
>> sample-rate of 192 kHz. Isn't 192 kHz overkill?
>>
>> I see reason for 96 but not 192.
>>
>> A 192 kHz sample-rate doesn't benefit a human with even the sharpest
>> ears. So why use it?
>


> What reason do you see for using 96 kHz? Nyquist says that 48 or even
> 44.1 kHz is adequate for producing sounds up to 20 kHz frequency. Why
> use 96 kHz?


A sample-rate 96 kHz is sufficient to prevent the non-linearities from
getting cacophonous. 192 kHz is un-necessary. In some cases, 44.1 kHz
and even 48 kHz is too low to prevent those effects. For just listening
to music, 44.1 kHz is fine. However, if you want to do some heavy duty
audio processing, then 96 kHz is best. That way the processing is likely
to cause unwanted artifacts.
From: Greg Berchin on 6 May 2008 17:45
Scott Hemphill wrote:

> This link is supposed to be such a sample. It's at 32kHz mono.
>
> http://audio.cbsnews.com/2006/06/12/audio1701350.mp3

I analyzed the sample. It's an almost pure sinewave at 15kHz,
amplitude approximately ±3500, with a short starting and ending
transient. When I played it, I experienced a sensation something like
hearing, but more like "being aware". Meanwhile my dogs not only left
the room, but exited the house and sought refuge in the back yard.
From: Scott Hemphill on 6 May 2008 09:39
glen herrmannsfeldt <gah(a)ugcs.caltech.edu> writes:

> Jerry Avins wrote:
> (snip)
>
>> 44.1/2=22.05 KHz, the maximum possible frequency that can be
>> reproduced according to simpleminded theory. 19 KHz is closer to the
>> practical limit. A few humans can hear frequencies higher than that,
>> so the answer must be no. It is sufficiently high to exceed the
>> hearing limits of almost all adults.
>
> So CDs for babies might run into the limit, but not for adults.
>
> This reminds me of a story about kids loading ringtones into
> cell phones that their teachers can't hear. What is the sample
> rate for cell phone ring tones?

This link is supposed to be such a sample. It's at 32kHz mono.

http://audio.cbsnews.com/2006/06/12/audio1701350.mp3

Scott
--
Scott Hemphill hemphill(a)alumni.caltech.edu
"This isn't flying. This is falling, with style." -- Buzz Lightyear
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