Noise reduction technologies for quieter cars
The quality of urban life is heavily influenced by noise and air pollution, and cars are responsible for a large portion of this. While recent agreements amongst vehicle manufacturers have addressed fuel efficiency, air pollutants and weight reduction, noise reduction remains a concern. The EU recently funded a project called 'Integrated solutions for noise and vibration control in vehicles' (CO2NTROL), also known as the Green City Car project. The aim of CO2NTROL was to integrate lab-tested noise-reduction solutions into a small city car to decrease noise emissions in these vehicles. Active noise-reduction approaches included an engine noise controller, a Helmholtz resonator and active noise control in the cabin area. Passive approaches included a new tyre design and incorporating new sound-cancellation materials into the car. Various options for each of these interventions were manufactured and either trialled in an industrial testing facility or installed and tested in a city car. A noise reduction of up to 7 dBA (decibels in the A-weighted system) has been achieved, as well as a noticeable improvement in sound quality. The sound-reduction measures tested for the Green City Car project have proved effective in decreasing noise output, which allows an increase in efficiency without compromising on sound quality. The findings of the project show good potential for use in the automobile industry and elsewhere.
