Locating primary sound sources in scattering media using multifrequency digital holographic reconstruction

Abstract

Multifrequency digital holographic reconstructions of primary sound sources embedded in scattering media are demonstrated. The sound field is measured with a scanning laser Doppler vibrometer ͑LDV͒ and broadening of the spectral content of the sound source is achieved by tuning the primary ultrasound ͑US͒ transducer around its resonance frequency. The results show that combining the complex amplitudes from the different frequency reconstructions results in a reduced susceptibility to multiple scattered sound and makes possible a quite thorough localization of the primary sound source. The depth resolution obtained is 11 US frequencies. This depth sensitivity is improved even further to only 2.8 wavelengths by applying a filter determined from the standard deviation over the phases.