Exporting mp3s: What is the big different between 48 kHz and 44.1 kHz?

Hi.
 
I have exported some mp3's at 320kbps.
 
What is the difference between 48 kHz and 44.1 kHz?
 
I can notice a difference and the 48 kHz sound nicer, a bit wider and not so squished. 44.1 kHz seems to be a standard to upload tracks, or sell them and sometimes to play them with certain music players.
 
Wav files are set at the 44.1 kHz. Isn't this suppose to be as near "cd quality" as possible?
 
Thank you.
 
P.S. Please look at my pages, they are in my profile. I have recently uploaded tracks, laid the web-pages all out. Need to add more people and any positive comments or constructive critisism is great. When this is done in the next 2 days, I will be able to go back and focus on making more music and uploading.

48k is often used in film and video editing since 48k divides evenly by both 24 and 30. --Neil

It may seem counterintuitive, but in most cases for a given data rate, a 44.1 kHz mp3 will be of higher quality than a 48 kHz mp3.

Here's why:
Using a very simplified example, if you encode a 48 kHz wav file to a 48 kHz mp3 file at 48kbps, each sample in the wav file gets allocated 1 bit.

If you encode a 44.1 kHz wav file into a 44.1 kHz mp3 at 48kbps (same data rate), each sample in the wav file gets allocated about 1.1 bits.

Depending on the mp3 encoder, there may also be different bandwidth settings when encoding at different sample rates.  For example, when encoding at 48 kHz, the bandwidth setting could be as high as 24 kHz and when encoding at 44.1 kHz the bandwidth setting could be as high as 22.05 kHz.  This means the bits pool used to encode the 48 kHz file has to cover a wider frequency spectrum than that same bit pool used for the 44.1 kHz file.  Because the bits in the 48 kHz file need to be spread out over a larger frequency range, there is a decrease the overall sound quality.

If you have an mp3 encoder that lets you set the bandwidth, try experimenting with it.  At lower data rates, you may find that you get better quality using a bandwidth setting of 18 or even 16 Khz.  By doing this you are effectively taking the bits that would have been used to encode frequencies where almost nothing is present and using them to improve the quality of the frequency range you are encoding.

You shouldn't be able to hear much of a difference between properly produced 44.1 and 48kHz files. What's more important is 1) what is your destination format, and  2) what is your source sample rate?

If you're intending this for CD you should bounce at 44.1k. If you're intending it for film/video you should bounce at 48k. If you're intending it for internet distribution/mp3 players? Not sure, but 44.1k is a more "universal" format.

Something recorded at 48k or 96k will probably sound better at 48k. Something recorded at 44.1k or 88.2k will probably sound better at 44.1k. Switching between 48k and 44.1k will probably degrade the sound quality a bit (depending on how good your software's "resampling" algorithm is. Sonar's is pretty good, but it's still best to reduce your need to resample as much as possible).

And yeah, for mp3s, the bitrate is going to be more important than the sample rate.

There was a video posted here some time back that totally dispelled the theory that the human ear could hear the difference between 44.1 and 48.  

they went into the reasons in scientific detail that escapes me now.  Kind of like..... does using the $100 gold plated cables make a difference in the sound that can be heard by human ears, over the normal $15 cables?  Again the answer was no. 

Picking the right audio sample was simply a matter of luck.. flip a coin and choose because the difference was not audible. 

NOW.... when you get into the lower MP3's rates 128kbs and such... yes, the differences there do become audible as the quality & rates go down. For THAT reason, if you convert to MP3, try to use the higher rates... 192 and up.