Hi,

The horn sound is made from a thin diaphragm shaped metal disc cause but magnetism from a coil of electric wire.
So yes that is how it starts. 😊

When the plate moves far enough in one direction it breaks a set of contacts inside very quickly.
The rapidness creates a frequency we can hear. It can be tuned to a certain extent but basically it’s the shape of the diaphragm and it surroundings.
Horns create a signature for car brands and size or luxury to a prospective consumer.
Much like mufflers can for the Dodge company. They have used a lot of research in that area.

If you are hearing a low tone it might be only one horn working, as there should be two on the brace.

It is a little different than hearing the sound of one hand clapping. 🤔.
That was a question in one of the Kung Fu TV series from the Master. The answer to the question was another question. What was it moving against.
It had to be Air first!
Moving that stuff is sound to our ears.

Elon Musk put a radio in the “dash shell” of a car and sent into space in a test flight.
I doubt he added speakers as extra weight or he was would have been laughed at. But then again, it was at least a smirk.


😊
Phil