I have a recording I am trying to prepare for a for a reunion of a friend who died 20 years ago. When I play the original cassette the recording is not garbled but so quiet I can barely hear it with the stereo cranked up…lots of hiss that way! With Audacity I’ve been able to remove most of the hiss, but it still sounds very muddy or underwater…not clear. I’ve played around with equalization, normalization, bass/treble, and a few other things but I really don’t know if I’m making any improvement or not. I don’t understand what all the levels do so I’m shooting in the dark. I’ve attached a clip where I’ve removed the hiss and no other changes. (I think I may have over-done the noise reduction a little) Thank you in advance for your help.
tim raw.aup (7.37 KB)
An AUP file is not audio, just a text file that says how to play the audio in the project’s _data folder.
If it is a Dolby tape, is the Dolby button on the tape deck pressed down?
If you want us to hear the audio, please see https://forum.audacityteam.org/t/how-to-post-an-audio-sample/29851/1 .
Gale
We’re not too good at CSI-type forensics. As you found, if the show is bad enough, we can’t make it better, we can only make it different bad. Rain-in-the-trees hiss is particularly bad news. Anything that removes hiss also removes sibilance and “hissy” sounds from the human voice turning it into mud.
There are technical tricks to force that to work anyway, but those usually sound like rushing water voices over silent gaps, or bad cellphones. By the way, one reason cellphone calls sometimes sound like that is they’re trying to remove background noise from somebody’s voice. Many of these tools use similar techniques.
Koz
My apologies on the file. I uploaded the wrong one but have included the WAV file now. The recording has always been muddy…barely audible. I don’t recall if the cd sounded better 30 years ago but I remember apologizing at Tim’s funeral when I handed his parents a copy because the sound was so bad then. I guess I’m hoping for a miracle.
That sounds like noise reduction has been applied, (the scribbling noise artefacts), if so it’s not “raw” .
There is very little above 2KHz, (should go to over 10KHz for a reasonable music recording).
It is possible you may have accidentally removed the high frequencies, making it muddy, when you applied noise reduction.
Here are two totally raw samples of the recording; One with dolby on while recording and one with it off.
Since I am uneducated in this area, I would appreciate specific suggestions, such as “try normalization at X setting”. 
Thank you to everyone who it taking time out of their day to help me with this recording.
In both of those recordings there’s essentially nothing above 2KHz other than hiss. Sorry we cannot bring out what isn’t there.
If the tape sounds like that (muddy) on different tape players then maybe just due to the age of the tape.
However the loss of high frequencies could be due to a particular tape player, (misalignment of tape with tape-head ).