BRUEL & KJAER HF HATS 5128 - Positioning Terminology; Standardized Positions

CHAPTER 4
Handset Positioner for HATS Type 4606 Features and Functions
43
4.3.4 Position
 A is measured off the end of the slide on the mounting bracket.  B and  C are recorded to the
nearest ½° using the markings provided on the swivel joints. In general the positioning accuracy
of Type 4606 when mounted on Type 5128 is ± 1 mm at ERP and ± 3 mm at MRP.
4.3.5 Standardized Positions
Typ e 46 06 i s eas y to set up fo r st and ardiz ed p ositions according to ITU-T Rec. P.64. The following
descriptions are valid for HATS mounted with Artificial Ear equipped with a pinna as specified by
ITU-T Rec. P.57.
Positioning Terminology
A Cartesian coordinate system is used to describe the standardized position by means of vectors.
Using ITU-T Rec. P.64 terminology, the coordinate system originates at CL and consists of three
axes called x
m
, y
m
and z
m
. The x
m
-axis has positive direction into the mouth and coincides thereby
with the mouth reference axis. The y
m
-axis is horizontal, perpendicular to the x
m
-axis with
positive direction towards the right side of the head and the z
m
-axis is perpendicular to the x
m
-
axis and y
m
-axis with positive direction upwards. This head-fixed coordinate system corresponds
to the HATS reference plane (see Fig.4.13).
Fig.4.13
Diagram of vector
directions for head-
fixed coordinate
system
Similar to the head-fixed coordinate system, a Cartesian coordinate system must be defined for
the handset. This coordinate system originates from the handset ECRP and defines three axes:
x
e
-axis is normal to the ear-cap plane with positive direction away from the earphone. The y
e
-axis
is the line of intersection of the handset symmetry plane with positive direction towards the
microphone. The z
e
-axis is normal to the other two axes and is for handsets applied to the right
ear. The z
e
-axis points obliquely downwards.
With these two coordinate systems in mind, the standardized positions as defined in ITU-T Rec.
P.64 can be set up as described in the following.
Refer to ITU-T Rec. P.64 for the exact vector definitions of the standardized positions.
980409/1
z
e
y
e
x
e
y
m
x
m
(backw)
z
m
(up)
ECRP
CL
ECRP, Ear-cap Reference Point
CL, Centre of Lips
B
C
A