Dear Mr. G:
You wrote:
>Is this sentence okay? To break the glass, you need to put out a sound that not only has the right frequency but is also loud enough to exceed the strength of the glass as it resists being vibrated.

It is a little wordy, but it is grammatically correct, and it does make sense. It might be a little clearer by making it two sentences or beginning the sentence with something like: “A sound that breaks the glass needs two qualities…”