Great workaround!

There are many programs that will allow you to create a silent file. GarageBand should do the trick... Audio Hijack Pro, Logic, and probably some test-tone generators would work too.

Also - don't worry, your dogs won't hear a thing because your computer is outputting with a maximum samplerate of 48kHz. Anything above half of that (ie above 24kHz) is filtered out to negate the effects of aliasing.

Craig

Most speakers will probably cut off well before 20 kHz. In addition, lots of digitized audio has already been pre-filtered before sampling at either 44.1 kHz or 48 kHz (for high-quality encoding). A typical response range for stereo computer speakers is 80 Hz - 15 kHz.

FWIW, you can test both your speakers and your own ears here: http://www.freemosquitoringtones.org

Anyone know how to create a silent MIDI-file?