What Determines a Transducer's operational frequency?

I'm looking to send a signal, but I dont know the precise frequency.
So Im wondering if the frequency is a strict physical property from the construction of a piezo electric, or other sorts of transducers,
or a range of frequencies.

I know there are a number of bright minds in our community that can offer solutions provided they are given the details. Describe in layman terms what you want to do. I'm confident you will get some responses, with less frustration, than the guess and by golly I got it right method.

maybe, but the entire process is expiramental rather than proven and well defined. Suppose I want to use resonance to detect ranges of granite, burried in various material sub-straight, with undefined depth, attenuation, and mass. thats the hand waving gist. maybe Ill start with a material with a well defined resonate frequency, and build up from there.

If you are trying to detect lumps of granite embedded in a matrix of soil that's one problem, if you are trying to detect granite road chipping dust embedded in a cyclist's knee - that a a different problem.

I'm thinking more like the former - so:

Typically lumps of granite under the ground don't have resonant frequencies in a useful way. Using sound waves or vibration to locate changes in density or stiffness in underground material is well established but doesn't use air coupled transducers or rely on resonance.

(As a side issue - granite (or any other solid compound) does not have a resonant frequency in the simple mechanical sense. An artefact or sample of the material may, or may not, depending on its shape and size. Some materials are more capable of producing resonant structures than others. Hard metals are good, custard - less so)

Please stop being so cagey about the problem.

Are you looking at a mm scale or km scale problem ?

If km scale the typical source transducer is a small bomb and the detectors an array of geo-phones.

If mm scale then maybe a piezo exciter.

In between, maybe a tapping machine.

MK

Mention substrate an a bright mind shines through:)

any DIY references to Using sound waves or vibration to locate changes in density or stiffness in underground material ?

You will need to do a lot of research.

Here's a start:

https://geologyscience.com/geology-branches/geophysics/the-seismic-method/

MK

You will need to do a lot of research.

Here's a start:

https://geologyscience.com/geology-branches/geophysics/the-seismic-method/

MK