Low coherence acoustic holography

Abstract

The quality of acoustic holography mainly depends on the measurement quality of a hologram plane. When we make a hologram by using “step-by-step measurement” using reference microphones, the measurement quality or “hologram quality” is directly related to the coherence between signals. In other words, if we have signals of low coherence, then it is very likely that we will have poor prediction of sound distribution on the un-measured plane. This low coherence is mainly due to what is related with multiple sources and measurement noise. This paper deals with what really happens and what are the important things when we use the step-by-step measurement for low coherence signals. As an example, the acoustic holography for the wind noise on the surface of a car is introduced.