I have tried to drastically lower the pitch of a piezoelectric buzzer, but to no avail. All the piezo buzzers I have emit a very high pitched whistle-like tone. I've tried changing all the parameters of my pulse generator, i.e., frequency, duty width, spacing, amplitude, etc. but the pitch of the tone remains the same, very high! Is it even possible to make a base tone from a piezo, or is the high pitch an intrinsic characteristic of all piezo units?
a plain, unadorned piezo disc transducer with no other circuitry affixed to it can be driven across a broad range of frequencies, which will make it vibrate. However, for it to vibrate strongly enough to easily make a loud noise, it needs to be driven at a frequency that coincides with its fundamental frequency of mechanical vibration.
Most piezo "beeper modules" contain a simple one-transistor oscillator that applies a sine or square wave to the disc at its fundamental resonant frequency. If you apply power to one of these, all you get out of it is that characteristic BEEEEEEEEEEEEP no matter what you do to it.