This is the absolutely most common myth when it comes to Digital Audio. Equally frustrating every time this topic shows up.
My background on the topic is among things like, sitting in with Tomas Lund and TC. Electronic in seminar about Digital Audio, Converters, Bit Rates and Sample Rates, Limiting and the Loudness War etc. In addition, I have a formal education in sound technical engineering (mid to late 90’s) and thousands of pages read on the topic (Lavry, Aldrich +++).
The hardest part is to tell this as simple as possible, so I will try a go on the Bit Rate and Dithering part first:
Higher bit depth gives greater precision in the amplitude domain = WRONG. 1st big misunderstanding across the internet.
As easy explained as possible:
0 dBFS in 24 bit = 0dBFS in 16 bit, No difference there.
1 bit = 6dB of Dynamic range.
16 bit x 6 = 96 dB of dynamic range (from 0 dBFS to -96 dBFS)
24 bit x 6 = 144 dB of Dynamic range (from 0 dBFS to -144 dBFS)
Try to think from the top and downwards. You have to think from the top and downwards.
The signal recorded in the top 96 dB range is exactly the same.
At -96 dBFS is were the difference comes in to play:
When your signal drops below -96 dB, the 16 bit will chop off the signal (the last bit will shut down).
The 24 bit signal has 48 dB’s of dynamic range left (for reverb-tail and other low level signals).
Here is also when Dithering comes into play:
When reducing the bitdepth to 16 bit from 24 bit, the dithering process will add some low level noise in the range that our hearing is least sensitive.
This is so to be able to keep the 16th bit (from top down) “open” as long as possible, to keep as much of reverb-tails and other low level details as possible (explained in the esiest way i could).
Conclusion:
If your signal has a Dynamic range of anything less than 96 dB’s and is located in the top 96 dB range, the recorded signal will be exactly the same.
The biggest misunderstanding is that the 24 bit scale has lesser “space” between measuring points (i.e.better). This is simply not true.
1 bit has only two values, on or off (1 or 0). Do the math and learn to think from the top and downwards.
That was the BIT part.
2x2x2x2x2… should be such an easy math. Don’t make it harder than it is.
Back to the 32-bit part: As all audio and real time processing (calculations - it’s just math) is executed in the 32-bit floating point realm, it doesn’t matter what Bit Size your source files are.
The only advantage of recording 32- bit files comes to play if you are doing a LOT of offline processing (post recording). That will make sure that rounding errors, after the offline processing/calculations, are “added” to the files at a level way way below human hearing.
My challenge to people who are gonna discuss Digital Audio (without wasting time, beleiving in Internet Myths), is to read all you can from reliable sources (google Nika Aldrich and Dan Lavry first). Listen to developers at big name Audio equipment manufacturers, not their marketing departement.
I will leave you with the best (and simplest) Digital Audio Myth breaking video there is (from bigger nerds than me):
Happy myth busting.