Here is a sample of one of my favourite 45s which I purchased in 1959 (yes, 48 years ago) and having been played so much it was getting a bit "worse for wear" so along with some others I cleaned them up and put them onto a CD.
If you would like to hear the samples you can download them by clicking on the links below using the Freewebs fast download system.
Lonnie Donegan before.mp3 Lonnie Donegan after.mp3
This sample is taken from the actual cassette sent to me from Colorado USA, by a lady who wanted to preserve the tape her father recorded for her. You will notice that the "before" has a lot of noise and large gaps which in the "after" have been edited out.
Gardner Lorenzo Hudson has made music from the time he was a young child growing up on a ranch in Colorado, on through adulthood, playing in dance bands, around campfires, in the oilfields where his profession as a welder earned him the nickname of "Sparky", and anywhere else available.
At 83.5 years old, he still drives into town, 2-3 times per week, "to entertain the old folks" as he puts it, in the nursing homes of western Utah.

Sparky Hudson before.mp3 Sparky Hudson after.mp3
R. I. P. "SPARKY". It is with much regret I have to inform you that Sparky Hudson is no longer with us. His memory lives on.
I must point out that with home made recordings the outcome depends largely on how it was originally recorded with regard to balance of voice/music, and whether it was single or double channel, however most can be substantially improved.

With professional pre-recorded sound such as commercial tapes and vinyl records and even the old 78s, the sound quality can in most cases be brought back to as good as new.