Yes, the existence of actual dynamic and frequency content can indeed be checked.
- Bit depth: check if there is actual non-zero or changing content in all of the bits. For example the "stats" effect of the SoX audio processing tool can give you the apparent bit depth of a file.
- Frequency range: check if there is actual frequency content above the Nyquist rate of a 44.1kHz sampling rate. This can be seen using frequency plots or other statistics.
Example: checking bit depth using SoX
$ sox --i 0001\ 8\ GR4.aif
Input File : '0001 8 GR4.aif'
Channels : 1
Sample Rate : 48000
Precision : 24-bit
Duration : 00:00:00.82 = 39424 samples ~ 61.6 CDDA sectors
File Size : 118k
Bit Rate : 1.15M
Sample Encoding: 24-bit Signed Integer PCM
$ sox 0001\ 8\ GR4.aif -n stat stats
...
Bit-depth 12/24
...
The documentation for the Bit-depth value says:
The right-hand Bit-depth figure is the standard definition of
bit-depth i.e. bits less significant than the given number are fixed
at zero. The left-hand figure is the number of most significant bits
that are fixed at zero (or one for negative numbers) subtracted from
the right-hand figure (the number subtracted is directly related to Pk
lev dB).
As far I understand, "12/24" means that the file does contain non-zero bits in the lowest 12 bits of 24 samples, but the 12 highest bits of all samples are zero. The output of the first command "sox --i file.aif" says that the file "is" a 24-bit audio file so that it could contain data in all 24 bits of each sample. However the second command prints out statistics from analysis of actual audio content, and it says that only the lowest 12 bits are used anywhere in the file. To show the actually used bits as X and unused or zero bits as 0, it would look like this:
000000000000XXXXXXXXXXXX
Let's take another example.
$ sox --i 0001\ 3-Audio-1.aif
Input File : '0001 3-Audio-1.aif'
Channels : 1
Sample Rate : 44100
Precision : 24-bit
Duration : 00:01:21.67 = 3601664 samples = 6125.28 CDDA sectors
File Size : 10.8M
Bit Rate : 1.06M
Sample Encoding: 24-bit Signed Integer PCM
$ sox 0001\ 3-Audio-1.aif -n stat stats
...
Bit-depth 16/16
...
This file "is" a 24-bit audio file as well, but this time only the 16 highest bits are used. Maybe the file was converted from a 16-bit file or recorded using an audio interface that only supported 16 bit audio, but the recording software had been told to store everything as 24-bit files anyway. It would look like this:
XXXXXXXXXXXXXXXX00000000
If you take a 16-bit audio file and convert it to 24 bit keeping "full scale" as is and without adding dithering noise or anything, it looks like that. Theoretically a 24-bit file, but only 16 bits of resolution is used.
I used to have a Yamaha 01v digital mixer with a 24-bit ADAT optical output, but it only used 20 bits out of the 24 because of its A/D converters and/or some other limitations. In other words, the 4 lowest bits of every sample coming from the 01v's ADAT output was all zeroes. Like this:
XXXXXXXXXXXXXXXXXXXX0000