I am recording my vocal to Audacity, accompanied on a separate track by music I composed on Sibelius. Went to Effects, Noise Reduction to get rid of a small amount of noise on the vocal track, and the final recording sounds great. Then I export it as an mp3 and play the mp3 in iTunes. Now there’s a hi pitched hiss behind the vocal that is not audibly detectable in the Audacity recording. Also, the overall quality is a bit diminished. I don’t understand why it apparently added the hiss, and what I can do to remove it. Using OSX 10.14 and Audacity 2.3.0. Thanks. --Tom in Texas
MP3 is lossy compression and it can affect sound quality,* but it won’t add hiss. Try exporting to WAV and that will tell you what, if anything, is related to MP3.
Noise Reduction can sometimes result in artifacts (sometimes a “metallic” sound) that rides on top of the audio.
- At high quality settings MP3 often sounds identical to the uncompressed original, but technically it’s always lossy.
You can take that upside down, too. Play your MP3 on Something Else.