Using P/Invoke you can play a beep through the PC speaker.
The P/Invoke prototype:
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool Beep(uint dwFreq, uint dwDuration);
dwFreq specifies the frequency, in hertz, of the sound. This parameter must be in the range 37 through 32,767 (0x25 through 0x7FFF).
dwDuration specifies the duration, in milliseconds, of the sound.
Example code to call the function:
Warning!!! Beep is NOT asynchronous so it does not return to the caller until the beep has finished
PInvoke.net Beep (Kernel32) reference