Ultrasonic Doppler sensor for speaker recognition

In this paper we present a novel use of an acoustic Doppler sonar for multi-modal speaker identification. An ultrasonic emitter directs a 40 kHz tone toward the speaker. Reflections from the speaker's face are recorded as the speaker talks. The frequency of the tone is modified by the velocity of the facial structures it is reflected by. The received ultrasonic signal thus contains an entire spectrum of frequencies representing the set of all velocities of facial components. The pattern of frequencies in the reflected signal is observed to be typical of the speaker. The captured ultrasonic signal is synchronously analyzed with the corresponding voice signal to extract specific characteristics that can be used to identify the speaker. Experiments show that the information this can result in significant improvements in speaker identification accuracy both under clean conditions and in noise.