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Chapter 1
Introduction
1.1 About this Manual
This manual covers the operation of High-frequency Head and Torso Simulator (HF HATS)
Types 5128-C and 5128-D, Tabletop HATS Type 5128-B, and all their accessories.
It also includes the associated Right Ear Simulator Type 4620-R, and Left Ear Simulator Type 4620-L.
For a description of the features and functions of Handset Positioner Type 4606 (included with
Type 5128-D), see Chapter 4.
1.2 HF HATS Types 5128-C and 5128-D
HF HATS Types 5128-C and 5128-D each consist of a head mounted on a torso, both of which
represent the international average dimensions of a human adult. In airborne acoustic
measurements it provides correct simulation of the acoustic field around a human head and torso
as specified in ITU-T Rec. P58 and IEC 60318 – 7. You can use HF HATS free-standing, or fitted on
a tripod or turntable using the tripod mounting adapter.
1.3 Tabletop HATS Type 5128-B
Tabletop HATS Type 5128-B is dedicated to testing all types of headphones. It uses the same head
that is supplied with HF HATS Types 5128-C and 5128-D, but instead of a torso, a support foot is
used to hold the head.
Tabletop HATS is configurable and typically includes two ear simulators, but normally does not
include a mouth simulator.
1.4 Mouth Simulator
The mouth simulator in HF HATS has a high-compliance loudspeaker that gives powerful low-
frequency response and low distortion. The acoustic transmission path from the loudspeaker to
the mouth opening ensures a frequency response of the sound pressure level in front of the
mouth, that can be equalized easily. The equivalent lip plane containing the ITU-T Centre of Lip
(CL), as defined by ITU-T, is 6 mm in front of the mouth opening. The usual calibration position
is at the ITU-T mouth reference point (MRP), 25 mm in front of this plane.
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