Sound image constructed by line array sweeping method

Abstract

There are various methods which can be used to visualize acoustic field of interest. Acoustic holograph is one of them. Comparing with other methods; for example, acoustic intensity mapping, acoustic holograph requires complicated, laborious, and costly measurement set-up. Therefore, there have been many researches which mainly convey the idea of which reduces or simplifies the measurement configuration into practically achievable one. In fact, STSF(Spatial Transformation of Sound Fields) essentially achieved this bjective. It uses a reference microphone and line array system. The array scans the sound field of interest step by step. This method is very powerful for measuring sound field which comes from stationary sound sources. Other than stationary sound field, such as non-stationary sound field but stationary in space, this method cannot be used. This paper introduces the way in which one can construct necessary hologram by using single line array. This method does not have limitation on the type of sound field. The theoretical formulation starts with introducing appropriate coordinate system which essentially uses three coordinate system; inertia, hologram, and microphone coordinate. The relations between these coordinates have been theoretically found. Various examples which include noise from running car, motorcycle, Zing; one of Korean gong, show the usefulness of the method.