BRUEL & KJAER HATS 4606, User Manual

Page: 60 / 68

High-frequency Head and Torso Simulator (HF HATS) Type 5128 – User Manual 52
DFR
Diffuse-field frequency response. The difference, in dB, between the third-octave
spectrum level of the acoustic pressure at the ear-drum reference point (DRP) and the
third-octave spectrum level of the acoustic pressure at the HATS reference point
(HRP) in a diffuse sound field with the HATS absent.
DRP
Eardrum reference point. A point located at the end of the ear canal, corresponding
to the eardrum position. See ITU-T P.57.
Ear simulator
Device for measuring the output sound pressure of an earphone under well-defined
loading conditions in a specified frequency range. It consists essentially of a principal
cavity, acoustic load networks, and a calibrated microphone. The location of the
microphone is chosen so that the sound pressure at the microphone corresponds
approximately to the sound pressure existing at the human ear drum.
ECRP
Ear cap reference point. The ECRP is the intersection of the external ear-cap reference
plane (ECRP Plane) with a normal axis through the effective acoustic centre of the
sound outlet ports. Generally, the acoustic centre of the sound outlet ports is at the
centre of their distribution. For many handsets, the ECRP plane is parallel to the
reference plane of the positioning device. When the handset is placed in the HATS
position, the ECRP of the device and the Ear Reference Point (ERP) of the ear simulator
will be coincident.
EEP
Ear canal entrance point. A point located at the centre of the ear canal opening. See
ITU-T P.57.
ERP
Ear reference point. A virtual point for geometric reference located at the entrance to
the listener's ear, traditionally used for calculating telephonometric loudness ratings.
See ITU-T P.57.
ERP-DRP
The sound pressure measured by the ear simulator is referenced to the ear-drum
reference point (DRP). The transfer function provided on the data disk will be used for
converting data to the ear reference point (ERP), when it is required to calculate
loudness ratings, or compare results with specifications based on measurements
referred to ERP.