Sound Quality Evaluation of Refrigerated Truck Noise
* Presenting author
Noise from refrigeration units on trucks can be a problem, particularly when the trucks are parked near residences. The development of a sound evaluation method that takes into account the strength of all sound attributes affecting people’s responses including level is described here. Such a model, coupled with a sound prediction methodology, would be helpful to unit designers who are concerned with optimizing a unit’s acoustical performance. The analysis of human subject responses to a variety of refrigerated truck sounds (in the third, of a series of three subjective tests) is described. Sixty participants rated 25 recorded and digitally modified refrigerated truck sounds as well as 25 residential HVAC equipment sounds. Fourteen sound quality metrics were evaluated as potential variables in a model to predict the average annoyance ratings of the refrigerated truck sounds. A rate-change-of-level metric that captured the impulsive character of the refrigerated truck unit noise was developed, and the best performing model contained it, a level metric and a spectral balance metric. The performance of the model when used with signals and ratings taken from other tests is described.