Transient Sound Intensity Measurements for Evaluating the Spatial Information of Sound Fields in Reverberant Enclosures.
Over the last twenty years, new subjectively relevant objective room-acoustic indicators for evaluating the acoustical quality of an enclosure have been introduced. While these indicators give new insight into the acoustical "Goodness" of a listener position, in order to design halls, assess or to correct an acoustical defect in an existing enclosure, there is a need to understand to what extent they are influenced by the physical design features of the enclosure. To meet such a need, information about the directional characteristics of sound is required. The spatial distribution of sound energy is usually not considered due to lack of an efficient, accurate and easy to perform measurement method. The main objectives of the present study are, first; to review known and speculative room-acoustic indicators for use in assessing reverberant spaces such as concert halls, opera houses, multi-purpose halls and churches. Second, to introduce an easy to perform measurement method for directional sensing in sound fields. Third, to develop a simple and inexpensive PC-based instrument primarily for the measurement of sound fields directional characteristics as well as contemporary room-acoustic indicators. Fourth, to propose new room-acoustic indicators which have relevance to directional information. This study introduces a three-dimensional sound intensity measurement technique for obtaining spatial information of sound fields in an enclosure. The technique has been validated and its accuracy investigated. The method gives results that provide valuable information regarding the directional behaviour of sound in enclosures. Subsequently both the system and the measurement method were applied to known spaces as example applications in order to assess sound quality, to detect the effect of the surrounding interior features of the space, and to assess potential diagnostic capability with respect to interior physical changes. The study has validated the measurement procedure as well as the importance and potential of visualizing the directional characteristics of sound fields at the listener position employing 3-D transient sound intensity impulses. In order to utilize the now-available directional information, existing temporal and spatial sound diffusion indices and techniques have been reviewed and additional prospective quantifiers are proposed. The study allows the possibility of developing an appreciation between cause and effect in the matter of interior architectural features design and by providing a better judgment base, removes much of the guess work to achieve cost effective remedial treatments. It also exposes a new dimensional perspective to workers developing objective indicators of subjective response.
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- Engineering: Civil; Physics: Acoustics; Architecture