This paper presents the experimental findings of a novel, single-camera method for measuring sound radiation fields generated by structural vibrations, using high-speed imaging and the frequency-domain triangulation method. Traditional acoustic measurements, which are vital in fields ranging from machinery diagnostics to architectural acoustics, often require specialized facilities and complex experimental setups. In contrast, this study demonstrates a single camera based, non-contact approach that provides high spatial resolution and is suitable for in situ measurements.
The method was tested on a baffled steel cylinder, excited in the frequency range up to 1500 Hz. By sequentially capturing high-speed video from 18 distinct viewpoints around the cylinder and applying frequency-domain triangulation on the DIC-computed displacements, we reconstructed its spatial operating deflection shapes at key frequencies. The camera-derived vibration data were used to model the sound radiation field, and validation tests with a laser vibrometer and microphone array showed close agreement between measurements.
This method accurately captures the vibrational deflection shapes and essential features of the sound radiation field, avoiding spatial discretization limitations of traditional approaches while maintaining the potential of robust field applicability. This study offers a promising alternative to traditional vibro-acoustic measurement techniques with reduced experimental setup complexity, particularly in environments where physical access to the structure is an issue.