A Review of Noise Directivity Testing

Noise directivity testing is used to characterize the radiation strength of noise from a sound source in different spatial directions. It is supported by national standards. Conventional testing is not applicable to moving sound source scenarios, in which relative motion exists between the sound source and sensors; the Doppler effect interferes with measurement, making it difficult to obtain accurate sound source amplitudes. This paper reviews conventional rotational scanning, beamforming, the Deconvolution Approach for the Mapping of Acoustic Sources (hereinafter referred to as DAMAS), near-field acoustic holography, and virtual sound field testing techniques. It compares the advantages and disadvantages of these techniques and clarifies the engineering roles of standardized tests and modern acoustic imaging techniques. The results show that conventional rotational scanning testing in anechoic chambers is suitable for static sound sources and is supported by well-established national standards, but it cannot be applied to moving sound sources affected by the Doppler effect. Quantitative imaging of moving sound sources requires point spread function correction and Doppler effect compensation to restore the true sound source strength. Conventional acoustic testing and array acoustic imaging can complement each other. In the future, acoustic testing will develop toward lightweight deconvolution algorithms, multi-technology integration, AI-enabled capabilities, and virtual-real fusion, thereby supporting noise control and the research and development of acoustic equipment.