Hiss when exporting as mp3

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.

Still noisy?