| As many of the more prominent automotive noise sources on a vehicle have become quieter, the attenuation of intake noise has become a primary focus for design engineers. This study was undertaken to experimentally determine if a non-conventional noise cancellation technique would be effective in improving automotive intake noise.; It is known that a noise source can be attenuated by cancelling the acoustic signal with another 'opposite' noise signal, usually generated by a speaker. The approach taken in this investigation was to cancel the intake noise of an automotive engine by using exhaust noise as the dynamic noise source. To accomplish this, a manifold bridging device was built to physically connect the intake and exhaust manifolds.; Using dimensional specifications determined from a previous analytical investigation, the intake noise for the engine with the manifold bridge installed was measured and compared to the noise measured from the original unmodified engine. In addition, three other manifold bridge configurations were tested and compared to the first 'standard' bridge, as well as to the unmodified engine. All experiments were conducted on a motored engine located within a semi-anechoic environment. (Abstract shortened by UMI.)... |
