Practical Sound Attenuation using Broad Band Sound Attenuating Devices

Reduction of annoyance from sound pollution is currently a subject of public concern and legislative action. We have a novel design of Broad Band Sound Attenuating Device, which can be configured to operate in a wide variety of situations. Our small-scale laboratory prototype performs better than conventional barriers, and its performance agrees with our Finite Element model predictions. A very important and beneficial property of our technology is its scalability. It can be tailored to attenuate sounds over the whole acoustic (and indeed ultrasonic) range. This means that it can readily be adapted to suit a wide range of applications. We have identified 2 key markets where legislation requires improved protection from sound pollution in the near future, namely:i) environmental noise from rail/roads and ii) protection from noisy machineryOur first aim is to extend our current models to full-scale simulations involving larger attenuators and realistic simulations of noise pollution. Having optimized the protection systems required for our two identified key markets we intend to build and test a full-scale demountable prototype for demonstration to potential industrial partners. This will be a system designed for protection from machinery noise since size and portability will be required. If time allows it is intended to construct a short section, modular construction barrier for use in road sound attenuation.In laboratory conditions our system offers good attenuation levels beating a mass law comparison. Initial research shows that the sound attenuation mechanism is virtually material independent, and poses a further advantage of blocking out low frequency sound without the need of increasing the mass of the barrier as with current technology (in current systems blocking low frequencies requires massive barriers). A successful outcome will lead to sound attenuation systems with wide applications throughout industry which offer major advantages over conventional systems.

This project builds on work from EPSRC grant EP/F005482/1 whose main research theme is terahertz radiation emitters, filters etc. based on metamaterials and similar spatially modulated materials consisting of resonators. During the modelling work on the project, it was found that an array of acoustic resonators may control sound in a way similar to that in which electromagnetic resonators control, emit and receive THz radiation. We aim to construct acoustic barriers using these acoustic resonators. The key potential impacts of our noise barrier technology will be major new business opportunities, enhancement of competitiveness and the opening of new markets by having a worldwide technological lead. Two keys areas, road/rail noise attenuation in built up areas and attenuation of noise from machinery, have been identified as targets for the new technology. The pre-cast concrete industries, for example, could benefit from a market lead in new noise barrier materials and processes that will substantially reduce material/maintenance costs. British Precast and Tarmac ltd have already expressed an interest in working to evaluate the new technology. This will enhance the competitiveness of the UK. New noise barrier markets will create new jobs, both in the supplier and from new export markets for the UK economy. European Noise Legislation requires each member state to prepare noise maps of larger towns and cities, and to publish action plans that identify noise standards and set out programmes to reduce levels to these standards. A follow on regulation to the Environment Noise (England) regulations, 2006 requires further reductions in noise limits to take effect from 2016. Our technology gives an ideal solution for national governments to confirm to these noise legislations. When full scale prototypes have been successfully realised and tested, key government stakeholders such as the Highways Agency and the Department for Transport will see major benefits. There will be significant potential impact from the substantial reduction of environmental noise. Interest could translate very quickly into active support for commercialising this technology. Tarmac ltd are very well placed as they work closely with both the end user for noise barrier technology i.e. Highways Agency, and to the supplier market, as they are the leading construction material supplier in the UK. The overall benefits of our technology and reduced noise levels are obvious as noise effects are both health and behavioural. Noise pollution can cause annoyance and aggression, hypertension, high stress levels, tinnitus, hearing loss, sleep disturbances, and other harmful effects. The costs to society of noise were estimated at 42 billion euros per year for EU-15, economic benefits from the reduce health costs are estimated to be 25 euros per household/decibel/year. Noise barrier projects in Europe have suggested that noise barriers can be integrated into the environment and have the potential to reflect current architectural trends. Construction of noise barriers not only benefits the end user, but also benefits, acoustic specialists, architects, construction workers, manufacturers of barrier elements, contractors, installation companies and governments. We plan to maximise potential impacts by: 1. Establishing and maintaining collaborations with developers of noise barrier technology in the UK. 2. The proactive participation of the LU Enterprise Office and our commercial champion to ensure that maximum industry and collaborator involvement is maintained throughout the project. 3. We aim to continue our presentations with industry and policy maker involvement (particularly the Highways Agency) 4. Communicating the results of our work via scientific publications, disseminating our results at international conference presentations, seminars, and discussion meetings.