Finite Element Model of an Ear Simulator

Pierre Gélat and Richard Barham

3 April 2003

Background

An ear simulator is a standardised device used for the calibration and characterisation of audiometers, earphones, and telecommunications and audio equipment.

Two types of ear simulator are widely used: the artificial ear standardised in IEC 60318-1 and the acoustic coupler standardised in IEC 60318-3.

Acoustic coupler and artificial ear

Description

The internal design of an artificial ear consists of three interconnected volumes to provide a complex impedance that mimics the nominal human ear

This is modelled using a lumped parameter approach, but its validity becomes questionable beyond a certain frequency.

A finite element model of the artificial ear has no such limitation. It can be used to:

– validate the lumped parameter model– model the characteristics of the ear simulator at higher frequencies

Artificial Ear Diagram

V2=1800 mm3 V3=7500 mm3

R1

L2 R2 L3 R3

Microphone

V1=2500 mm3

25mm

Axisymmetric model of artificial ear: pressure contours at 8 kHz

Conclusions

Poor agreement with lumped parameter model

Need to include viscosity effects

Working with PACSYS Ltd. to develop 1-D and 2-D viscous fluid finite elements