Problem: Sometimes I don’t hear any sound from Safari or Firefox while playing content from multimedia websites (e.g., YouTube). Curiously, sites that stream QuickTime files come through just fine; it’s just the embedded video files that don’t produce sound.

Cause: If you work with lots of sound apps (SoundHack, Audacity, etc.), one of them may have inadvertently munged some of the the Mac’s core audio settings.

Fix:

  1. Open Audio MIDI Setup (/Applications/Utilities/), then check the Audio Output setting.
  2. Change the Audio Output setting to 44100.0 Hz.
  3. Quit Audio MIDI Setup.
  4. Restart the app (e.g., Firefox).

See the Apple tech article “Mac OS X: No audio from certain multimedia content” for more details.

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