Scan and Paint: theory and practice of a sound field visualization method

Traditional methods, such as step-by-step measurements or simultaneous multichannel systems, have a strong trade-off between time requirements, flexibility and cost. However, if the sound field can be assumed time stationary, scanning methods allow us to assess variations across space with a single transducer, as long as the position of the sensor is known.

The proposed technique, Scan & Paint, is based on the acquisition of sound pressure and particle velocity by manually moving a P-U probe (pressure-particle velocity sensors) across a sound field whilst filming the event with a camera. The sensor position is extracted by applying automatic color tracking to each frame of the recorded video. It is then possible to visualize sound variations across the space in terms of sound pressure, particle velocity or acoustic intensity. In this paper not only are the theoretical foundations of the method explored but also its practical applications such as scanning transfer path analysis, source radiation characterization, operational deflection shapes, virtual phased arrays, material characterization and acoustic intensity vector field mapping.