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The University of Southampton

Research project: Generation of Multiple Independent Listening Zones in a Vehicle Cabin

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The generation of independent listening zones in a car cabin would allow each occupant to listen to a different audio programme without the constraints of headphones.

Generating independent listening zones in a car cabin
Independent listening zones

The car cabin is probably one of the most extensively used listening environments and is used to listen to many different audio prorgrammes such as music, video, navigation system instructions, telecommunications and warning sounds. Due to this proliferation of audio sources and the different requirements of the different occupants of a car, there is a desire to produce multiple independent listening zones. This would enable the different occupants to listen to different audio without interfering with one another.

Independent listening environments are readily achievable using headphones; however, wearing headphones for prolonged periods may become fatiguing and is a safety issue for the driver. This project, therefore, investigates the ability to produce independent listening zones in a car cabin using loudspeakers.

To understand the physical acoustic limitations associated with generating personal listening zones in a car cabin, numerical simulations were first conducted. These simulations highlighted that the four standard car audio loudspeakers were only able to achieve control at low frequencies due to the modal characteristics of the car cabin enclosure. To achieve personal listening zones over the full audio bandwidth it is necessary to introduce additional loudspeakers positioned in closer proximity to the car cabin’s occupants’ heads. This has been achieved by positioning two small directional loudspeakers at each headrest, as shown in the adjacent photo.

The personal audio system employs headrest mounted directional loudspeakers
Headrest loudspeakers

The full personal audio system has been implemented in a small people carrier and uses the four standard car audio loudspeakers at low frequencies and eight small headrest mounted loudspeakers at higher frequencies. The audio signals driving the individual loudspeakers has been processed to generate independent listening zones in the front and rear of the car. The system is able to achieve 15 dB of isolation between the two listening zones.

Associated research themes



Signal Processing and Control

Related research groups

Signal Processing, Audio and Hearing Group




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