First of all, sorry if this is not the right stackexchange site to ask this, but here it goes.
For research and learning purposes I want to record wav files at different sample rates and bit depths and compare the recordings, listen to their differences, etc.
The sample rate part is rather easy, many programs like Audacity in linux give this possibility. Also the bit depth is easy, but I cannot find a program or command that would allow me to record at lower bit depths than 8-bit.
I'm aware that this is probably impractical and also that 8-bit is a byte and probably that's the reason why programs don't usually go lower than this, because of integer data types representation. But for learning purposes and from a theoretical point of view, it should be possible to record an audio signal at arbitraty low bit depths such as 2-bit, 4-bit, etc.
For example, in the Audacity Wiki (http://wiki.audacityteam.org/wiki/Bit_Depth#sources), it is mentioned that a cassette is equivalent to a 6-bit depth, and that an Edison Cylinder home recording is as low a 2-bit depth in resolution.
So, my question is, do you know of any program or command that would allow me to record at lower-than-8-bit depths? (Preferably linux). If not, can you explain why this seems not easy to do with default/most common linux programs (Audacity,
EDIT: I've found this very interesting article about speech processing in different sample rates and bit depths, which is precissely the field I'm investigating also: http://iitg.vlab.co.in/?sub=59&brch=164&sim=474&cnt=1
Source: (2011). Sampling Frequency and Bit Resolution for Speech Signal Processing. Retrieved 11 June 2016 from http://iitg.vlab.co.in/?sub=59&brch=164&sim=474&cnt=1
However, I cannot seem to find which programs or techniques are used to record at low bit-depth, or if they record at 16-bit and then lower the bit depth of the already recorded signal (I believe this is called "bit crushing" technique?).