Yes, you are correct - but it doesn’t work like that - I’ll make this simple for you to understand.
If you tune a system/beam/whatever to a specific resonance it will resonate most freely at his resonance. You will have a primary resonance and then harmonics at double the frequency and multiples thereof. Look at the dB HL curve in terms of SPL and the amount of roll off at the HF (and LF) before you start thinking about it. What you think of as consistent levels of gain over several pitches ISN’T.
Take this a step further, hearing aids are mainly designed for SPEECH, therefore receivers (Look at the Knowles Tech bulletins, data-sheets and support notes ) are designed around the same principle. Most speech occurs in the 250Hz to 6Khz range, therefore the basic receiver design is a rising response to 1KHz with a damped sinusoid tail. This gives a response shape somewhat like a porcupine’s back, depending on the beam/reed resonance caused by the interaction of the magnets and coil in the balanced armature set-up.
Given your vast experience in this field, you’ll know that the area under the curve is the amount of power possible. Now, you can fart around with this area, but unless you increase the drive voltage you can’t increase it. Therefore, if you WANT a response that goes out to 20Khz you can (in theory) do it - however, we aren’t providing hearing aids for bats. In the process however you move the peak out of the sweet spot in the middle of the dB HL weigting and have a lower response overall to reproduce a load of Frequencies you could only just hear when you were 30.
Lets throw some more issues in - Hysteresis ? Drive rod weld fatigue? Reed stress? Diaphragm material failure? Just say Twenty Thousand times a second in your head and then apply that to a physical system with components that are measured in millimetres with tolerances in microns.
If you’ve got any more ideas on how to make things better let Knowles know.