Hi. I'm trying to measure the milliseconds of duration of output from a little piezo speaker that is on a circuit (a freezer control unit). I tried connecting an oscilloscope across its leads, but when I apply power, I hear this resonating noise which does not sound healthy. This is only when the device is powered. Any suggestions on why this might be? This noise ONLY occurs when I have the oscilloscope connected. What else might I try to measure this (other than a microphone)?