Non-invasive and Locally Resolved Measurement of Sound Velocity by Ultrasound

• Main Authors: Mario WOLF, Elfgard KÜHNICKE
• Format: Article
• Language: English
• Published: IFSA Publishing, S.L. 2015-01-01
• Series: Sensors & Transducers
• Subjects: Ultrasound annular arrays; Measurement of sound velocity; Locally resolved; High frequency approximation; Integral transform method.
• Online Access: http://www.sensorsportal.com/HTML/DIGEST/january_2015/Vol_184/P_2585.pdf

A new method to measure sound velocity and distance simultaneously and locally resolved by an ultrasound annular array is developed in media with constant sound velocity and then applied in media with continuously changing properties. Instead of using reflectors at known positions the echoes of moving scattering particles are analyzed to determine the focus position. Although the method reaches a very high accuracy for constant sound velocity, there are systematic deviation between measurements and sound field simulations using Fermat’s principle. The sound propagation has to be described with a modified wave equation. A new approach determining GREEN’s functions for a half space with continuously changing properties is presented. It combines the high frequency approximation with an integral transform method.