Air Ultrasonic Signal Localization with a Beamforming Microphone Array

Abstract

Nondestructive testing methods are used to inspect and test materials and components for discontinuities or differences in mechanical characteristics. Phased array signal processing techniques have been widely used in different applications, but less research has been conducted on contactless nondestructive testing with passive arrays. This paper presents an application of beamforming techniques analysis using a passive synthetic microphone array to calculate the origin and intensity of sound waves in the ultrasonic frequency range. Acoustic cameras operating in the audible frequency range are well known. In order to conduct measurements in higher frequencies, the arrangement of microphones in an array has to be taken into consideration. This arrangement has a strong influence on the array properties, such as its beam pattern, its dynamics, and its susceptibility to spatial aliasing. Based on simulations, optimized configurations with 16, 32, and 48 microphones and 20 cm diameter were implemented in real experiments to investigate the array resolution and localize ultrasonic sources at 75 kHz signal frequency. The results show that development of an ultrasonic camera to localize ultrasonic sound sources is beneficial.

Generating Airborne Ultrasonic Amplitude Patterns Using an Open Hardware Phased Array

“…The ability to produce dynamic ultrasonic fields with target shapes is of fundamental importance in ultrasonic imaging [1], nondestructive testing [2,3], and high-intensity focused ultrasound HIFU therapy [4]. When operating in air, there are numerous emerging applications that require the generation of acoustic fields with certain shapes, such as noncontact tactile feedback [5][6][7], volumetric displays [8,9], parametric audio generation [10,11], and the contactless manipulation of objects [12][13][14][15][16].…”

Resonant Airborne Acoustic Emission for Nondestructive Testing and Defect Imaging in Composites

“…However, commercial acoustic cameras are barely applicable to the detection of ultrasound, since they mainly operate in audible frequency ranges [6,7].…”

Listening for Airborne Sound of Damage: A New Mode of Diagnostic Imaging

“…For this reason, commercial acoustic cameras mainly operate in an audible frequency range and cannot be directly applied for conventional ultrasonic imaging of defects where the frequencies of some 100 kHz are required for reasonable resolution (Movahed et al, 2019). Nonetheless, the feasibility of acoustic camera imaging was demonstrated in (Pfeiffer et al, 2013) for a guided wave scattered by an impact damage in a honeycomb composite sandwich.…”