Audacity Forum

Which version of Audacity?
Do any of the tracks have empty space at the start?
Do any of the tracks have sound before time=0? (indicated by small left pointing arrows at the start of the track)

I use Blue Yeti microphone (USB microphone) and listen to sound using headphones Perhaps the mic is picking up a bit of sound from your headphones. Fully enclosed headphones usually have less "spillover" than ear buds or open back headphones. You could try reducing the sound level in your...

If you duplicate a track and apply a slight vibrato to one track and not the other, it will create a "phasing" type effect.

Audacity does not do "real-time" processing. Any changes that you wish to make to the sound are applied after you have recorded.
A section of audio may be repeated using the "Repeat" effect: https://manual.audacityteam.org/man/repeat.html

There is no hum on the original, when I listen to it with earphones played on the same USB cassette capture. There IS hum on the audacity internal project, before the MP3 is saved to my computer. Hum is an analog phenomena. Once the signal is converted from analog to digital, it becomes immune to p...

What happens if you Right click on Audacity in the Dock and select "Open"? (with your normal user account)

You could try https://www.wavosaur.com
It's not open source, but it is free and it supports ASIO. They claim that it can record multi-channel audio. It may not be suitable for editing multi-channel, but if you can record and export a multi-channel WAV, then you can do your editing in Audacity.

"MP4" is a container format. Inside the MP4 there may be an audio stream (and/or a video stream). MP4 supports a wide range of audio codecs, including AAC, MP3 and others. Some codecs use floating point representation, which, like Audacity's 32-bit float PCM format, can go over 0 dB.

FFmpeg will either be updated or replaced some time in the future, but there are a lot of competing issues vying for the attention of the Audacity developers, and there are very few Audacity developers. How I can use ffmpeg v4? Currently, FFmpeg v4 is not compatible with Audacity, though you could u...

To annoy you.