Inside every cellphone lies a tiny mechanical heart, beating several billion times a second. These micromechanical resonators play an essential role in cellphone communication. Buffeted by the cacophony of radio frequencies in the airwaves, the resonators select just the right frequencies for transmitting and receiving signals between mobile devices.

With the growing importance of these resonators, scientists need a reliable and efficient way to make sure the devices are working properly. That’s best accomplished by carefully studying the acoustic waves that the resonators generate.

Now, researchers at the National Institute of Standards and Technology (NIST) and their colleagues have developed an instrument to image these acoustic waves over a wide range of frequencies and produce “movies” of them with unprecedented detail.

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