An electronic device (100) includes a component portion (101) and a strap (102). The strap defines an air chamber (402) therein having a corresponding volume. A driver (403) is disposed in the component portion at a first port (404) between the component portion and the strap. A frequency detector (405) is disposed in the component portion at a second port (406) between the component portion and the strap. A control circuit (407) is operable with the driver and the frequency detector and is configured to determine a peak of a resonant frequency over a frequency range in the air chamber with the frequency detector that are a function of the corresponding volume and are responsive to signals produced by the driver, correlate the frequency of pressure variations determined with a user input, and perform an operation based upon the user input.