> 24 bit audio depth matters,

Please forgive me but I'm not going to just accept someone's word on this when the science seems to point in the other direction.

Is there any properly conducted test that backs this up?

Case in point. The bit rate has to do with dynamic range not frequencies.

The reverberation of a single tone can be in phase or out of phase. The results is observed as a beat frequency in amplitude.. not in tonal frequency, that's what why bitrate matters.

We use higher bitrates during recording to lower the noise floor, in turn giving more headroom in the mix. Once you mix down this becomes irrelevant because the difference between silent and full volume at 16bit is enough to cover the full capability in terms of sound pressure levels of the human ear. 1bit = 6dB which means 16bit is 96dB. As we don't start at absolute zero but with a background noise of the room at 30dB using the full dynamic range of 16bit at playback you risk deafening yourself.

In your example if your single tone is out of phase then 1) how do you control this at any bit rate and 2) this is controlled by an acoustically treated room and a skilled engineer during recording. When you listen on headphones you already eliminate this concern on playback and unless you are listening in a professional designed and treated listening studio you will always have some element of phase cancellation. This is the listening character of your room and will occur at any bitrate.

Read this https://www.mojo-audio.com/blog/the-24bit-delusion/

You know - I agree with this article. Thank you for your thoughtful response.

I understand and agree that 24bits is enough for human perception. But something else is happening in MP3 encoding. Some sort of assumptions about human perception of dynamic range that are inaccurate. I am not expert enough to know precisely where. But I generally understand compression and I am an "audiophile".

Nothing in the article stands out as false to me. But I cannot help but believe it might be missing something.

> Particularly when their phase is slow in time

What does this mean?

Compressors variably quantize a frequency band based on what is considered to be imperceptible to human ears. Imagine a standup bass is sustaining a note. That has a bunch of different resonances based on; strings, the wood of the bass, and the geometry of the room. In a live setting, those material properties create interference between the source of the sound and the reflection. But they're very quiet and can reverberate on the order of seconds. So most compressors will quantize the constructive/destructive dynamic range to the same value.

In rock music this doesn't matter so much. But orchestras may even use the room geometry as an effect.