Parametric Sound Fields Formed by Phase-inversion Excitation of Primary Waves

Document type: Journal Articles
Article type: Original article
Peer reviewed: Yes
Author(s): Tomoo Kamakura, Hideyuki Nomura, Masahiko Akiyama, Claes Hedberg
Title: Parametric Sound Fields Formed by Phase-inversion Excitation of Primary Waves
Journal: Acta Acustica united with Acustica
Year: 2011
Volume: 97
Issue: 2
Pagination: 209-218
ISSN: 1610-1928
Publisher: S. Hirzel Verlag
URI/DOI: 10.3813/AAA.918400
ISI number: 000288130700004
Organization: Blekinge Institute of Technology
Department: School of Engineering - Dept. of Mechanical Engineering (Sektionen för ingenjörsvetenskap - avd. för maskinteknik)
School of Engineering S- 371 79 Karlskrona
+46 455 38 50 00
Authors e-mail: ,
Language: English
Abstract: Two planar ultrasound pro jectors having identical rectangular apertures were placed side by side. Both pro jectors radiated bifrequency primary waves in air. The frequencies were 26 and 28 kHz, and the initial phases were different. Two driving modes were considered, namely, conventional in-phase driving and phase-inversion driving. The spatial profiles of sound pressure fields were measured along and across the sound beam axis for the primary waves and a difference in frequency waves of 2 kHz. The second and third harmonic components of the difference frequency waves were also measured. The pressure levels of the primary waves were considerably suppressed near the beam axis owing to phase
cancellation when the driving signals were phase-inversed, i.e., 180 degrees out of phase.
The beam pattern of the difference frequency was, however, almost the same as that for the case in which the signals were in phase. Interestingly, the harmonic pressure
amplitudes of the difference frequency were reduced by more than 10 dB. The validity of the experimental results were confirmed based on their good agreement with the theoretical predictions based on the Khokhlov-Zabolotskaya-Kuznetsov equation.
Subject: Mechanical Engineering\Structural Dynamics
Mechanical Engineering\Structural Mechanics