Two factors would need to be considered if you use lower sample rates
First, of course is that you are aware of and have no intention beyond simply listening. With that in mind you could use 48KBPS.
Second and more important, you will need to record through a bandpass filter to block anything over 8 kHz. Reason is that should an insufficient sampling rate be used, based on the audio frequency, the possibility of aliasing increases dramatically. This can result in secondary sounds in the lower frequency regions as the sample rate hetrodynes with the higher audio frequency components. Thus these will need to be blocked to prevent them from entering the recorder'
As to the sound quality You may notice a slight difference between 48 KBPS and 96 KBPS, but not appreciably. When I conducted my tests here I used simulated EVPs containing audio components up to 15 kHz. The tests were conducted using a Fostex FR2 digital recorder. This recorder can sample up to 192 KBPS, but can also be dongraded to lower rates. One could see no appreciable difference between 192KBPS and 96 KBPS. on a scope nor could you hear any. When you drop down to 48KBPS you could observe a 3 db rolloff at 15 Khz over the 96 KBPS. Listening wise it was barely noticable. Not serious but that was were it first became apparent. Below that it was much greater and could be easily heard as well. Thus my resoning for setting these values. In a pinch 48 KBPS should work OK. Certainly better than the 8 to 14 K that most digital voice recorders use!
Thanks. I appreciate the time you took to respond.