Development of an active noise control earplug

Abstract

Active Noise Control (ANC) is used in controlling low frequency noise where passive control is ineffective. This paper presents the main results obtained from the development of an active noise control earplug for use in industry. A simple analogue feedback control system is used to demonstrate the potential of the system. Experimental results show that with existing miniature microphones and loudspeakers characteristics, adequate active noise reduction occurs in the frequency range between 100 Hz to 1000 Hz. The peak noise attenuation of about 15 dB occurs around 400 Hz. A model of the electroacoustic control system is provided and used to predict the performance. Simulation results show that the system secondary path frequency response dictates the closed-loop performance. The response in turn depends mainly on the frequency responses of the microphone and loudspeaker. The controller is used to maximize the noise reduction and its bandwidth. If lower frequency noise reduction is desired, the transducers responses must extend over a wider frequency range. 25th International Congress on Sound and Vibration 2018, ICSV 2018: Hiroshima Calling. All rights reserved.