Josie,
To continue, when you record, you have two things you need to worry about. Sample Rate, and Bit Depth. Today, most recordings are done in either 16 bit or 24 bit, although you will see 32 bit floating once in a while.

Think of a graph for me, please. As we move from left to right in the horizontal plane, we increase our sampling rate. Along with the sampling rate, our highest frequency that can be recorded increases as well. So, as I said before, Nyquist says that the sample rate must be twice that of the highest frequency sampled. Sampling at 48kHz gives you a 24kHz frequency range.

If we move up the graph, we increase our bit depth, which equates to our dynamic range. Remember, Dynamic Range is the range, in decibels, from dead quite to the loudest sound we can record in digital. Each single bit gives us 6dB or range. So, an old 8 bit recorded would give us a total of 48dB of dynamic range. My conversations are in the 55-70dB range, depending on how agitated or excited I am. A standard CD has a bit depth of 16 bits, giving you 96dB of Dynamic range. Twenty four bits will give you a dynamic range of about 144dB, but the thing is, you get into electron flow noise at that level. The gear I work on, our top of the line A/D converter, will top out in the -127 to -130dB range. That's a pretty substantial noise floor, and that's without A-Weighting.

Let's go back and discuss these numbers some, okay?

A rock concert may have SPL, or Sound Pressure Levels in excess of 140dB! That is actually damaging to hearing, but they still do it. Now, if you're recording at 16 bit, you have a 96dB dynamic range. How do you compress 140dB into 96dB? Well, that's pretty easy, actually. You attenuate the input level so that at the maximum SPL you're getting to the maximum of the converter, which is this case is 96dB. Ahhh, but what about the really silent parts? In a straight recording, they may be lost. Subtract 96 from 140, and you have 44dB. Now, that 44dB is your noise floor, not zero. Anything below 44dB is lost. This is where compressors come into play. If you have a compressor before the inputs to your A/D converter, you can squish the sound to get all 140dB of the concert range into a 96dB dynamic range for a CD.

Okay, none of this answered your question earlier, though. If you upsample a 44.1kHz, 16 bit signal to 48kHz, not much is going to happen. You're adding frequency range and bit depth, which are basically zeros. Downsampling, for most people, you will not hear a difference. There are some who will, but most, it's doubtful. Remember that most recordings today are recorded at 96/24, and then downsampled to 44.1/16 for CDs.

I hope this helps you a bit.

Gary

I'm blessed watching God do what He does best. I've had a few rough years, and I'm still not back to where I want to be, but I'm on the way and things are looking far better now than what they were!