Ear Simulator Types 4620-L And 4620-R - BRUEL & KJAER HF HATS 5128 User Manual

2 High-frequency Head and Torso Simulator (HF HATS) Type 5128 – User Manual
Type 5128 is equipped with chin clip that will hold a 1/4 reference microphone at precisely the
correct distance for calibration at the MRP. This chin clip can also hold a microphone at the
opening of the mouth to monitor or equalise the sound pressure at this point.
The mouth simulator produces a sound-pressure distribution around the opening of the mouth
that simulates that of an average adult human mouth, correlating with the figures given in
ITU-T Rec. P.58. The position of the acoustic centre of the mouth simulator also follows that of
humans over the speech frequency range.
1.5

Ear Simulator Types 4620-L and 4620-R

Ear Simulator Types 4620-L and 4620-R consist of a soft, silicone-rubber pinna with a hardness
close to a real human ear pinna connected to an average human ear canal. The ear canal ends in
an occluded ear simulator that simulates an average human ear drum. The occluded ear simulator
contains a 1/4 microphone and is connected to a microphone preamplifier.
Type 4620-R is the right ear of Type 5128, and Type 4620-L is the left ear of Type 5128. Both ears
are delivered with calibration information and a calibration chart specific to the entire ear
simulator. Sound Calibrator Type 4231 is a suitable calibrator for these ear simulators.
The combined influence of the torso, head, pinna and ear-canal on airborne sound signals can be
quantified by the acoustic free-field transfer function (the frequency response from free-field to
the eardrum). This is called the listener free-field frequency response (LFR) in
telecommunications and the mannequin frequency response (MFR) or the head-related transfer
function (HRTF) in technical audiology.