Mixer Toolbar
From Audacity Manual
Output Volume Slider: Sets the playback volume.
Input Volume Slider: Sets the recording volume.
Input Device Selector: Depending on your system, may allow selection of different inputs such as microphone or line-in (for devices such as record players or cassette decks).
These sliders control the mixer settings of the sound card.
The sliders will jump to zero (left most position) if the sound card drivers do not
give Audacity access to these functions. This is the case with some digital I/O cards
from RME. Sound cards that have a custom mixer application rather than the standard OS volume control usually won't work with this function of audacity.
On these cards you will not be able to control anything with these sliders. You will need to set up the recording levels and the recording source using the card's mixer program.
Output Slider
This is the left hand slider that lets you control the output level of your sound card. It actually controls the output setting of the sound card driver.
Should your output sound distorted, this is not the first place to look. You might get lucky though, so give it a quick slide. Usually however, the distortion comes from the mix of your project clipping. You actually need to reduce the level of your tracks. It is suggested you reduce every track by the same amount.
Input Slider
This is the right hand slider that lets you control the level of the input selected in the Input Selector. It controls the recording level setting of the sound card driver.
What you record is also determined in the mixer settings on your sound card. There you can switch certain sources on and off, such as the Line Input, the Microphone Input or the CD Audio.
After selecting the corresponding input source with the Input Selector, you can control the level of the recording with this slider. Use the VU Meters on the Meter Toolbar to get the correct recording level.
Should your input sound distorted, you should lower this slider until no distortion can be heard, and the VU Meters do not hit the end of their travel.
Input Selector
