From Audacity Wiki
"Dropouts" are small fragments of missing audio on recording. They can sometimes be caused by very slow processing, especially slow writing to disk or USB key, when writing data cannot keep up with the recording.
- We have added dropout detection for this release.
|If you are certain that your recordings do not suffer from dropouts, you may wish to turn this new option "off".|
Dropout detection is controlled from a setting in Recording Preferences called "Detect dropouts".
- When this setting is "on" (default setting) Audacity will detect dropouts (brief gaps in the recording) and will insert zeroes into the recording to keep the other good parts synchronized. These silent spans will make the dropouts more obvious, but keep the duration of the recording correct.
- Dropouts may be caused by a disk drive that cannot keep up with the recording. This can happen, for example, with a slow USB or network drive, or if antivirus software is slowing writing to disk, or if other activity on the computer is slowing the computer down.
- When recording stops, a Warning message box alerts the user and a label track, called "Dropouts", is added showing the lost parts, labeled with consecutive numbers.