Source: Section 3.5 (page 9) of this peer-reviewed meta-analysis days “it is well known that the dynamic range of human hearing may exceed 100db. Therefore, it is reasonable to speculate that bit depth beyond 16 bits may be perceived.”

https://qmro.qmul.ac.uk/xmlui/bitstream/handle/123456789/134...

Additionally, this is purely talking about loudness dynamic range, not even including resolution or JND (just noticeable difference). I will demonstrate to you below how even 20 bits per sample is insufficient in some cases.

Imagine for a moment that you could argue that the human hearing threshold of quantization error is only 4 bits (only 16 discrete values!) at the sound level of a pin dropping (10db). Now, I think we can all agree that’s absurd; we need a lot more than just 16 discrete amplitude values to represent the sound of a pin drop indistinguishable from reality to a human ear. But for the moment, let’s be really really generous to your point and assume it’s enough!

Now, let’s suppose we want to extend the recording so sounds at 110db appear later on (say, an intense bass explosion in an action movie after a quiet scene early on). To do this without clipping, what range of discrete values do we need? 110db-10db = 100db = 100,000x greater amplitude than the pin drop. This means we need to be able to represent peak amplitude values of 1,600,000.

This exceeds the ability of 16 bits to losslessly represent the quiet 10db pin drop and 110db explosions within the same movie’s audio track! You would need at least 21 bits in this example. And I’ve been generous with my assumptions here, making the extreme assumption that even 4bits per sample is enough to record a 10db pin drop, which is clearly not enough.

If you think 110db is unrealistic for brief periods, it’s not, even for music: bass frequencies in particular can reach extreme amplitudes that might surprise you. I recently played an extremely well recorded orchestral piece at reference volume on my equipment and was so impressed by the dynamic range, I later measured the decibel levels (C-weighted). The quietest moments are around 65-70db, increases to 80-90db at times, and peaks several times momentarily to 105db when the bass drum hits (you feel it like a punch of an air wave)! It turns out this is exactly how real bass drums measure. Yet, the drum hit doesn’t sound unbearable loud (as treble would be at that decibel level), so much as tactile, because much of that energy is subsonic.

If you do much research into perceptual psychology studies, you’ll see just how surprisingly difficult it can be to completely pin down the limits of human perception on average, let alone including outliers among the human population. In that sense, it’s entirely reasonable that a durable high fidelity recording format that holds up to time should be over-engineered, so there’s at least no worry that some study will prove it’s missing something later.

That said, I don’t really agree with the parent post that most DACs are horrible, but I can’t comment on CD player DACs since I don’t use physical media. Most phone DACs are quite good. Most PC DACs are horrible not because of the DAC but because buzzing noises from system clocks and other sources always appear on my speakers (it’s very loud and noticeable), so I’m forced to use a cheap $20 external DAC, which quite frankly is nearly as good as anything else you’ll get at any price.