Vibro-Acoustics of Flat-Panel Speakers with Attached Lumped Masses

Abstract

In recent years, a number of patents have been devoted to the development of flat-panel speakers. Among them, one patent is about the use of interior elastic restraints to help stabilize the motion and smooth the sound pressure level (SPL) curves of flat-panel speakers. It is important that the sound radiation behavior of a flat-panel speaker can be accurately predicted when the optimal system parameters of the speaker are to be determined. In this paper, a simple yet effective method constructed on the basis of the Rayleigh-Ritz method and the first Rayleigh integral is presented for the vibroacoustic analysis of flat-panel speakers with masses attached to the interior elastic restraints of the speaker. In the proposed method, the interior elastic supports are modeled as discrete springs and the masses at the interior restraints are treated as lumped masses attached to the back surface of the plate. The displacement field of the sound radiation plate of the speaker is formulated on the basis of the first-order shear deformation theory. The accuracy of the proposed method has been validated by the experimental SPL curves of an orthotropic flat-panel speaker with interior elastic restraints at different locations and having various attached masses. The effects of the locations of the interior elastic restraints and the magnitudes of the attached masses on the sound radiation characteristics of the orthotropic speaker are studied using the proposed method. It has been shown that the proper use of attached masses in the design of flat-panel speakers can help improve the SPL curves of the speakers. Keywords: Acoustics, audio, composite materials, elastic support, plate, speaker, sound pressure, vibration, flat-panel speaker, sound radiation.