A dog whistle produces a sound at a frequency higher than the human ear can perceive. Humans can hear sounds at up to around 20,000 hertz; dogs, on the other hand, can hear sounds at up to 48,000 hertz. Using a dog whistle allows you to train your dog without subjecting any other people in earshot to the whistle. If you want to move your dog training into the digital age, you can create a virtual dog whistle sound file using the free audio editor Audacity.
Launch Audacity. Click "Edit," then select "Preferences." Click "Quality" in the left-hand column.
Select "96000 Hz" from the "Default Sample Rate" drop-down menu. Click the "Default Sample Format" drop-down menu and select "32-bit float." Click "OK."
Click "Generate" in the top menu bar, then click "Tone." Click the "Waveform" drop-down menu and select "Sine." Double-click the "Frequency (Hz)" field and type "22000" without quotes.
Right-click the "Duration" field and select "Seconds." Click the zero immediately to the left of "seconds" and type "1" without quotes.
Click "OK" to create the dog whistle sound. Click the "Play" button to "listen" to the sound. Click "Stop" to stop the dog whistle.
Your speakers' frequency response must be wide enough to play extremely high-frequency sounds. Inexpensive computer speakers are unlikely to have this type of frequency response. Turn your speakers' volume down before playing the dog whistle sound: your dog can hear it!