The cabs of large dump trucks operating on mineral working and construction sites were found to have A-weighted noise levels of about 95 dB.
The cabs were situated immediately beside the engine compartments and separated from them by plain sheet steel bulkheads. The vehicle construction itself was one of an all-welded, undamped steel plate that resulted in noise and mechanical vibration emissions from the engine and gearbox.
A three-fold approach to noise reduction was taken: the large surface areas of the cab, roof, bulkhead and door panels were treated by the application of 10 mm thick bitumastic damping pads to reduce resonant vibration; a proprietary sound barrier mat consisting of a lead/fibreglass laminate was applied to the floor and engine bulkhead; an acoustically absorptive foam was applied to all available surfaces inside the cab to reduce reverberant sound build-up.
About £1500 (a new vehicle can cost over £200 000). (1995)
A noise reduction of up to 11 dB.
Information supplied by EMD Services.