Prev: Acoustic memory
Next: What's the use of a 192 kHz sample rate?
From: Jerry Avins on 4 May 2008 10:00
Green Xenon [Radium] 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?

Radium,

You've come a long way since the days of a fraction of a bit per sample!

You will find as you actually make something work that having a generous
margin over the minimum needed -- wiggle room is one way to put it --
makes the task easier and the finished result better. For example, while
16 bits is sufficient for a good finished product, a few extra bits (24
is nice) allows one to change gains and mix tracks without losing
anything significant to the listener. Every modification can be at best
as good as the original. In practice, most lose something. Starting with
more than the necessary minimum provides the margin that makes the loss
immaterial.

Whenever the sample rate might be subject to modification, that applies
not only to bit width, but to sample rate. When separately recorded
tracks are mixed, tempo adjustments might be needed.

It is not inconceivable that a guitar's high E string could support my
weight. If I were to be lifted to any appreciable height, I would hope
for something more robust. It's always nice to have something extra.

Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
From: Jerry Avins on 6 May 2008 17:04
Scott Hemphill wrote:
> 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

I didn't hear a thing. :-) (Neither did my school-teacher son.)
My better ear is 60 dB down at 8 KHz (30 dB down at 3 KHz).

Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
From: glen herrmannsfeldt on 6 May 2008 02:37
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?

-- glen

 | 
Pages: 1
Prev: Acoustic memory
Next: What's the use of a 192 kHz sample rate?