Disclosed are an electronic device and method for detecting the proximity of an object. In an embodiment, the electronic device includes a communication module, a sound emitter, a sound receiver, and a processor. The processor receives at least one part of a voice signal from a calling party through the communication module, and determines whether there is a voice idle time in the at least one part of the voice signal. When the voice idle time is present in the at least one part of the voice signal, the processor outputs a sound wave in an inaudible frequency band through the sound emitter during the voice idle time. Then the processor receives, through the sound receiver, sound wave in the inaudible frequency band reflected from an object. Next, the processor may detect whether the object is proximate to the electronic device using the reflected sound wave in the inaudible frequency band.