Every bit of word width gives you 6 db of dynamic range. 16 bit is therefore 96db. of dynamic range. 60db is approximately the range we hear from barely audiable to loud - I did say approximate. A CD is 16 bit.

24 bit audio gives you more range but most of the best hardware has about a 108db range give or take a few. 108db works out to 18 bits of audio. Arguably more is better but you have to take into account the noise floor of the source.

My Canon ZR65 has about a 45db noise floor when I use the inbuilt microphone so 16 bits is plenty. Some hotel meeting rooms have very loud air conditioning units which greatly raises the nose floor.

If I want the ultimate I record in 24 bits provided my hardware supports it. Usually 16 bits is just find and I have produce several CD's that way. DV is 12 or 16 bits and no seems to recommend 12 bits. Forget about 8 bits - thats telephony quality.

As far as space it's pretty linear, 24 bits takes up 50% more space that 16 bit.

This may be more than you wanted but it's interesting stuff.

larry