Abstract: Aquatic vehicles may use electric motors for propulsion, such as brushless motors. As an example, a speed of these motors can be controlled using a pulse-width-modulated (PWM) electrical signal that varies the motor speed by varying pulse parameters within the PWM signal. PMW modulation can cause the motor to emit significant acoustic noise into the environment. In a fluid medium, such as aquatic environment, such noise can be detected with hydrophones or other acoustic sensors. The subject matter described herein can include modulating a signal provided to a motor to provide a communication signal to be mechanically (e.g., acoustically) emitted by the motor in a fluid medium, such as an underwater medium. In this manner, the motor can function both as a source of propulsion, and as an electroacoustic transducer (e.g., a transmitter).