Wax Guard Acoustics: Transfer Matrix Computation
Application ID: 77691
In this tutorial, the acoustic properties of a wax guard are analyzed. A wax guard is a small perforated mesh used to protect the receiver (the miniature loudspeaker in a hearing aid) used for receiver-in-the-ear (RITE) or receiver-in-canal (RIC) hearing aids. Because of the very small dimensions of the structure the thermal and viscous boundary layer losses need to be included in detail, and therefore the Thermoviscous Acoustics, Frequency Domain interface is used.
In the first step, the transfer matrix (or two-port) of the wax guard is computed using the Port Sweep functionality and the Port boundary conditions. The wax guard geometry is imported from a CAD file and prepared for simulation.
In the second step, the response of the wax guard sub-system, when placed in a typical measurement setup, is computed and compared to actual measurements. This is done using the lumped transfer matrix approach. The computed wax guard transfer matrix is used together with other transfer matrix components for a receiver (miniature loudspeaker), a narrow pipe, and a coupler volume.
This model example illustrates applications of this type that would nominally be built using the following products:
however, additional products may be required to completely define and model it. Furthermore, this example may also be defined and modeled using components from the following product combinations:
The combination of COMSOL® products required to model your application depends on several factors and may include boundary conditions, material properties, physics interfaces, and part libraries. Particular functionality may be common to several products. To determine the right combination of products for your modeling needs, review the Specification Chart and make use of a free evaluation license. The COMSOL Sales and Support teams are available for answering any questions you may have regarding this.