Development of a Vibration-based Acoustic Sound Power Measurement Method

Brigham Young University, Provo UT

Investigators

Abstract

As many as 40 million adult Americans have hearing loss from loud noise and 30 million Americans are exposed to hazardous noise levels every day. As a society, we are becoming more aware of excessive noise around us, and the discomfort and health problems it creates. To address this problem, engineers and designers need efficient methods to include noise test data in the product design process. Current standards and methods for measuring sound power, which is the metric used to quantify noise produced by a product, require specialized acoustic chambers such that sound power testing is typically expensive and time consuming. As a result, sound power testing may not even be done, which limits the ability of designers to focus on and minimize noise in their products. This research will focus on developing a new vibration-based sound power measurement method that will allow engineers to efficiently acquire and use noise data to improve their products. The new method is not limited by many of the restrictions of current sound power measurement standards and can be used to make truly in situ measurements saving companies significant time and providing improved products. A number of standards exist for measuring sound power. However, these typically have restrictions such as requiring specific acoustic fields, reflective surfaces, and no varying background noise. A new vibration-based method will be developed that is designed to overcome a number of these restrictions. This new method treats the structure as an array of small, individual radiators, and estimates the sound power through the calculation of self- and mutual-impedances between the radiators. Expressions for these impedances have been developed for simple ideal structures. This research will utilize these expressions to validate the method of obtaining the sound power from vibration measurements. It will then focus on developing the theoretical and computational tools to account for arbitrarily shaped structures, coupled built-up structures, and components of built-up structures. Experimental verification of the new method will be carried out for these more complex structures by comparing results using the extended computational tools with results from existing standards. By overcoming some of the restrictions of current standards, the new method will also be used for truly in-situ testing. The new method is not meant to replace all other methods, but it will provide a practical vibration-based alternative. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.