High Frequency info point of view/food for thought

[kap'n krunch]

I know I am opening a can of worms but I thought I'd share some very interesting info regarding what NASA (!?) has found regarding how our EYEBALLS react to high frequencies.
As an audio professional, I know that in a blind test I'd not be able to distinguish 96K from 48K signals-although I would hear the difference between 16bit and 24 bit but, hey, if 96K has been adopted in the music world,it must be for some reason, right?
I myself love all the tickling I get when I hear all those HF, especially now that I have some Industry Standard Adam A7V monitors.
This is from a quite recent LP version of Scheherazade, hope you guys find it interesting.. I found it fascinating...

 

[jimfisheye]

AD and DA converters need an anti aliasing eq filter in the analog stage to prevent any frequencies over the Nyquist limit of the sampling rate from aliasing.

If the data band goes right up to the sample rate, this is critical! Aliasing will corrupt the data band. SD sample rates have the audio band right up to the sampling limit. Analog crossover style eq circuits are a challenge. You're hearing corruption of the audio band from dodgy anti aliasing filters in SD sample rates vs HD sample rates. 96k has a passive wide margin between the audio data and the sampling frequency.

It's no more, no less than that. You have the full audio data in both examples. Poor quality DAC or ADC anti alias filtering in the SD examples used to be more prevalent. Most modern converters have a more strict circuit design for the anti aliasing filter now. Many consumer AVRs will still upsample as a passive workaround though too.

Meanwhile, bit depth relates to dynamic range. If you want to have the lowest levels of your program have at least 8 bits resolution, the max dynamic range above that with 16 bits is 48db. On par with higher end vinyl playback (with a good pressing). Some classical and art music needs just a little more! 24 bit gives you 96db with minimum always at least 8 bits and this covers everything.

I just think it's worth pointing out the nuts and bolts of this so people don't mistake it as something subjective "only some people can hear" as though it's a mystery. We can hear distortion from poor quality crossover eq and we can hear clipped or distorted dynamics.

 

[barfle]

I recall more than a few people saying they didn't like digital sound because it was stepped and not smooth like analog. Well, maybe there was something in the digital audio they didn't like, but it wasn't steps.