In another question I posed, there were couple of "piezo sounder" parts suggested for the purpose of a compact but reasonably loud, alternative to electro-mechanical hooters.
Was trying to understand the various device characteristics that these "pieze sounders" have, and how I could use them to generate a sound-pattern (involving at-least 2 different frequencies), without sacrificing too much on the "loudness" aspect.
This is where I ran into "resonant frequency" of piezo elements, which is mentioned in all the data-sheets. So my question is, is this the frequency at which the device is loudest but it is still possible to generate tones at other frequencies, possibly with reduced loudness ? None of these data-sheets provide a graph of the loudness-vs-frequency characteristics for the device. So I am wondering if the piezo sounders with "resonant frequency" mentioned (but missing the graph), can produce sound at only one frequency ?
The two SE QnA's referred to: