Re: Is 44.1 KHz sample-rate enough? Yes and No.

Dave Platt wrote:
> In article <48180c72$0$7713$4c368faf@[EMAIL PROTECTED]
>,
> Green Xenon [Radium] <glucegen1@[EMAIL PROTECTED]
> wrote:
> 
>> I want my audio system to be able to record, process, playback,
receive, 
>> transmit, generate, reproduce and otherwise perfectly-handle audio and 
>> ultrasonic acoustic signals as loud as 200 dB without any clipping and 
>> as high-frequency as 300 GHz without any aliasing.
> 
>> 300 GHz is the highest ultrasonic acoustic frequency that can exist in 
>> Earth's atmosphere, as you can see below.
> 
>> Igor wrote in http://www.lns.cornell.edu/spr/2006-11/msg0075905.html
:
> 
>> "The mean free path in air at sea level is about 0.1 micron[1]. Let's
>> take the speed of sound to be roughly 300 m/s. Then the upper limit on
>> sustainable sound frequencies is
> 
>> f_max = (300 m/s) / (10^-7 m) = 3*10^9 Hz = 3 GHz."
> 
> And, as Bob Morein explained to you in some detail back in December of
> last year, the mean free path travel distance is *not* the primary
> limiting factor on the upper frequency which can be carried through
> the air via sound.  Rather, it's the kinetic energy of the
> molecules... and this limits the upper frequency to around 30 MHz.
> 
> Similarly, the "200 dB" maximum SPL you ask for is meaningless
> (assuming you're referencing it to the usual "0 dB" standard of
> pressure, which is set to the minimum volume level that a human
> listener can detect in an otherwise-silent environment) since it
> exceeds the theoretical limit for the passage of undistorted sound
> through atmosphere at sea level (which one reference gives as being
> 194 dB).  You cannot have "200 dB" and "perfectly handle... without
> any clipping", because the air itself will distort the signal.
> 
> It's also far, *far* above the "threshold of pain" (at which the sound
> becomes unbearable to the listener) and the "threshold of damage" (at
> which irreversable damage to the listener's hearing can occur even due
> to short exposures).
> 
>> Unfortunately for me, this audio system of mine is way too good to ever

>> be true.
> 
> It's not just "way too good to ever be true".  It's defined in a way
> which is actually *meaningless*.
> 
> And, if it weren't meaningless, it wouldn't be an audio reproduction
> system.  It would be a weapon of war.
> 


Ok, I forgot to add some additional details about my audio system:

1. First and foremost, it does not emit sound/ultrasound of any 
intensity that would cause any harm or discomfort [physical or 
psychological] to any living organism. Safety first. The entire system 
can perfectly attenuate a 200 dB signal down to 0 dB without 
experiencing any distortion. One of the reasons my audio system should 
be able to handle such high-amplitude signals is so that it can survive 
those amplitudes without experiencing damage. Also it needs to be able 
to handle high-amplitudes it is going to attenuate loud signals. This 
audio system is designed for smooth jazz, soft rock, and light punk -- 
such as Phil Collins and Blink 182. Those who like the loud heavy metal 
songs of Creed and other loud-mouths will not want my audio system 
because the attenuation would make the originally-loud sounds too soft 
to give the feel of heavy metal. My system can actually scan through 
tracks of songs recorded into it. As it scans a track it will attenuate 
everything in the track until the loudest sound is soft enough not to 
cause any harm, discomfort, or startle response in the listener. You 
could have this audio system in a room that is initally in total silence 
and then suddenly turn the volume to max. Even then, the loudest sound 
will not cause you any hint of startle.

2. It does not concern me that the air would not be able to carry 
mechanical vibrations as high-frequency as 300 GHz or as loud as 200 dB 
SPL. In fact, it further drives my curiosity to find out what would 
happen if one attempts to force the air to carry acoustic vibrations at 
frequencies significantly higher than what the air can carry.

3. My entire audio system has the physical ability to handle even the 
nastiest of clipping without experience any amount of damage. It can 
handle 200 dB square waves without experiencing any damage or generating 
any perceptible heat. [A precautionary measure just in case there is 
some hard-clipping somewhere in the amp]. Let me assure you though that 
my audio system will never actually playback any signal that loud 
because the system is designed not generate unwanted/harmful sounds.

4. Only sounds that are high-frequency enough not to cause any injury to 
any living organism will get anywhere near 194 dB. [Assuming such a 
"loud" ultrasound could actually be harmless].

5. Can't stress this enough -- safety first! safety first! safety first! 
safety first!