Communicating under extreme noise conditions remains challenging in spite of higher-order noise-canceling microphones, throat microphones, and signal processing. Both natural and man-made background ambient noise can disturb the conveyance of information because of high volume and/or extreme frequencies. Noise cancellation, which is used frequently in audio technology, has limits in noise reduction and does not guarantee clear vocal pickup in these severe situations. A contact microphone that is attached directly to the medium of interest has the potential to pick up vocal signals without reduced noise. In this study, an electrostatic transducer with an elastomer layer that is impedance-matched to the human body is used to pick up speech sounds through constant contact on the chin and cheek. By attaching the wearable device directly to the skin, the medium of air is bypassed, and airborne noise is passively canceled. Because of the acoustic impedance-matched layer, the sensor is more sensitive to low frequencies under 500 Hz, so frequency equalization was implemented to flatten the frequency response throughout the vocal range. The perceptual evaluation of speech quality (PESQ) scores of the wearable device with equalization average around 2.5 on a scale from –0.5 to 4.5 in comparison to a dynamic mic without noise. Speech recordings were also collected in a noise field of 85 dB, and the performance was compared to a cardioid lapel mic, a cardioid dynamic mic, and an omnidirectional condenser mic. The recordings revealed a significantly reduced presence of white noise. This study provides preliminary results that show potential in vocal applications for a wearable impedance-matched sensor.
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Wearable impedance-matched noise-canceling sensor for voice pickup
Published:
15 November 2023
by MDPI
in 10th International Electronic Conference on Sensors and Applications
session Electronic Sensors, Devices and Systems
Abstract:
Keywords: Wearable device; Acoustic noise; Transducers; Speech communication; Microphones; Noise cancellation
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