FOR IMMEDIATE RELEASE
4 June 1999
ARTIFICIAL EARS REDUCE INTERIOR NOISE BY 45 PER CENT
Nissan has created a pair of artificial human ears to help engineers study interior noise levels. The ‘ears’ have been used for the first time during the development of the new Primera, as a result interior noise has been reduced by up to 45 per cent.
Cabin noise reduction is important both in terms of comfort and also safety. A quieter cabin aids concentration and reduces driver fatigue. Special attention was paid to sound frequencies that interfere with conversation or listening to music.
The artificial ears record sound digitally using microphones that are as thin as a human ear drum. The microphones are implanted into the heads of test dummies to reproduce the way the driver and passengers hear sounds. However the microphones’ sensitivity far exceeds the normal human range of hearing.
During development of a vehicle, cabin noise is accurately recorded at various speeds and on many different road surfaces. The digital recordings are then analysed using techniques similar to those used in the music broadcasting industry.
This effectively creates a digital model by which Nissan’s engineers can experiment with the vehicle’s acoustics and simulate new ideas, before making actual design changes.
Artificial ears reduce interior noise by 45 per cent…2
Over 40 major changes have been made to the new Primera to improve ambient noise. They range from re-tuned suspension bushes to an under floor stone-chip coating which deadens road noise from loose gravel. Extra soundproofing has been put behind the instrument panel and headliner material has been acoustically-optimised.
Around 6500 man-hours of investigation have gone into reducing sources of noise inside the new Primera. Peter Sendall, senior development engineer at the Nissan European Technology Centre said: “Our ability to objectively quantify and analyse sources of interior noise has been dramatically improved with the introduction of our digital ‘listening’ technology. It has enabled us to take the new Primera to the top of its class.
“At 62mph road noise is now reduced by 20 per cent. For typical motorway driving, new Primera is now 45 per cent quieter.”
The new Primera, which goes on sale in September, will be built at Nissan’s Sunderland car plant. The interior noise reduction programme was carried out at Nissan’s testing facilities in Sunderland and the Nissan European Technology Centre in Cranfield, Bedfordshire.
Some 5,400 people are employed directly by Nissan in the UK. The company’s operations include vehicle styling, manufacturing, distribution and sales, industrial machinery and finance.
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For further information please contact:
Lesley Alder 0191 419 3300
e-mail lesley.alder@nissan-nmuk.co.uk
Stewart McKee 01923 899 930
e-mail stewart.mckee@nissan.co.uk
Pictures are available via ISDN from Dave Foster; northpoint@connectfree.co.uk or telephone 01207 580 921, or mobile 0802 662960
24848/040699