BRUEL & KJAER 4128-C - CHAPTER 2 Characteristics; Construction of the Head and Torso Simulator

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Chapter 2
Characteristics
2.1 Construction of the Head and Torso Simulator
Head and Torso Construction
The shell of Head and Torso Simulator Type 4128-C is made up of three parts: the torso, which
is in one moulded piece and cannot be dismantled, and the two halves of the head (front and
back). The procedure for separating these parts is given in Chapter 1.
Mouth Simulator Construction
Fig.2.1
Construction of the mouth
of HATS
The construction of the mouth simulator of the HATS is shown in Fig.2.1. It features a high-
compliance loudspeaker and has a carefully adjusted acoustic transmission path between the
loudspeaker and the sound radiation opening which ensures that the sound pressure level in
front of the mouth is easily equalisable with respect to frequency.
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Protection
Circuit
Loudspeaker
Mouth
Adaptor
6 mm
Mouth
Reference
Point (MRP)
25 mm
Equivalent
Lip-plane
Ref.
Microphone
Holder
Center of
Lip (CL)