The University of Southampton
Engineering and the Environment

Research project: The effect of active noise control on the sound quality in cars

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Active Noise Control (ANC) can be used to reduce noise and vibration. It works best at low frequencies, when the wavelength is comparable with the dimensions of the enclosure. In humans, however, low frequency sounds can make sounds at higher frequencies less audible. This effect, known as masking, can be important when considering the low-frequency attenuation of ANC since the sound of higher frequency components may become more audible when they are no longer masked. The aim of this project is to research the use of models of masking in the control strategy of ANC systems and to determine the perceived effect of the sound quality before and after active control.

Project Overview

The 'Green City Car' project is a collaborative attempt to control noise and vibration in lightweight, eco-friendly vehicles. Traditionally, noise control is achieved through passive methods, including the use of foam cladding and heavier, thicker materials to reduce low frequency vibration and noise transmission. Such schemes increase weight and take up space, but if cars are to become more fuel efficient and eco-friendly, then alternative, low-weight alternatives should be used. Active Noise Control (ANC) can also be used to reduce noise and vibration. It works best at low frequencies, when the wavelength is comparable with the dimensions of the enclosure. In humans, however, low frequency sounds can make sounds at higher frequencies less audible. This effect, known as masking, can be important when considering the low-frequency attenuation of ANC since the sound of higher frequency components may become more audible when they are no longer masked. Therefore it is possible that the reduction in loudness, as heard by a human listener, may not be as significant as a sound level meter may suggest. The aim of this project is to research the use of models of masking in the control strategy of ANC systems and to determine the perceived effect of the sound quality before and after active control. Future aims of this project include the investigation of the physical origin of these masking effects, using a numerical model of the non-linear active cochlea in order to predict and explain how and why they occur.
CollaborationsThis research is part of the 'Green City Car' project which is funded by the European Commission under the Seventh Framework Programme. Project Reference: SCP8-GA-2009-233764

Related research groups

Signal Processing and Control Group

Staff

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