From Audacity Manual
Why have I lost sound after connecting a USB device on Windows?
When you connect a USB audio device to a Windows computer, it may automatically become the "default" device that is normally used for both playback and recording. If the USB audio device is not meant as a playback device for the computer (such as a microphone, turntable or tape deck) you may lose sound in Audacity or in most programs on your computer. You can fix the problem as follows.
- Windows Vista, Windows 7, Windows 8: Right-click over the by the system clock, choose , then right-click over the speakers or headphones device you are using, choose "Set as Default Device" and click "OK".
- Windows XP: Right-click over the by the system clock, choose , then click on the Audio tab. In the "Sound Playback" panel, click on the downward pointing arrow in the dropdown box, select the inbuilt soundcard as the default device and click "OK".
Alternatively, you can disconnect the USB device from the computer after you have finished recording.
Note: To hear audio while you are recording, ensure "Software Playthrough" is "on". This can be toggled on/off by clicking.
Why does playback go quiet when I record or adjust the recording volume?
You may notice this on Windows 7 or later, for example when recording overdubs while playing an existing track. This system setting turns down or mutes other sounds when audio goes through the recording or playback devices set as "Default Communication Device" in Windows. This feature can be useful when making or receiving internet phone calls but is undesirable for other audio. To turn off this adjustment:
- Right-click over the by the system clock then choose
- In the dialog that opens, click the
- Underneath "When Windows detects communications activity", choose "Do nothing" and click "OK"
- On the Playback and Recording tabs, you can optionally right-click over a device and set or unset it as "Default Communication Device."
If there are other problems with audio inputs or outputs not interacting properly, make sure your sound device has the latest drivers specific to your particular computer model and operating system. The drivers should be obtained from the motherboard or computer manufacturer's website, or if not available there, from the sound device manufacturer's website. For more help, see our Wiki page Updating Sound Device Drivers.
Why do I hear clicky playback on Mac OS X?
This is most likely to occur if you use Soundflower or an external USB or Firewire playback device rather than the built-in audio output. The problem can usually be fixed by opening Recording Preferences and adjusting the "Audio to Buffer" setting which also affects playback. Reduce the setting to 0 milliseconds. If playback breaks up or does not start, increase "Audio to Buffer" in increments of 10 milliseconds until playback is smooth.
Why is there a very low level hiss on exported files?
Deliberate low-level noise is normally added when you downsample to a lower sample format, for example when you export from a project at default 32-bit depth to a 16-bit WAV or AIFF file, or when you run effects on a project containing 16-bit audio. The additional noise is known as dither and is generally beneficial. Dither prevents clicky noises which might otherwise occur due to not being able to accurately represent 32-bit values in a 16-bit format.
If you still want to turn dither off for all data processing (including export) you can do so at "High-quality Conversion" in Quality Preferences. Alternatively you can turn dither off just for the export step. This may help avoid cumulative dither noise if you are exporting regularly over the same file.
How can I pause playback so I can edit there?
Audacity cannot edit audio while the playback stream is paused because the stream is still active. You can press the yellow Stop button or press SPACE to stop, but this sets the editing cursor back to the point from which playback started.
To stop playback and set the cursor where you stopped, so that playback resumes from there, press SHIFT + A on your keyboard. Using either SPACE or SHIFT + A will then start playback from that stop position.
There are many other alternative workflows, depending on your purpose. Here are two examples:
- Instead of stopping at each edit point, keep playing and use CTRL + M ( COMMAND + . on Mac OS X ) to add a label when you hear each point of interest. After stopping, click in any label to set the cursor there for editing.
- While playing and listening for an edit region, use [ on your keyboard when you hear the start of the audio you are interested in, then press ] when you hear the end of the audio of interest. The ] shortcut draws a selection region from the point where you pressed [ to the point where you pressed ]. Now you can press SPACE twice to easily stop playback then play that selection.
You can change any of the above shortcuts in Keyboard Preferences.
See Navigation Tips for useful ways to find the audio you want to edit then mark points or regions for cutting.
How can I play or export multi-channel (surround sound) files?
Audacity can export multi-channel files by enabling "Use custom mix" in Import / Export Preferences. You will need to adjust the mapping of tracks to channels in Advanced Mixing Options according to the channel order of the format you are exporting to, though some files or playback software/hardware might not necessarily respect that order.
However Audacity playback is currently limited to mixing down tracks to mono or stereo (two channels). Therefore only mono or stereo channels will be listed in the Playback Device in Device Toolbar.