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thresholds for the HA-1, HA-2 (DB 0138) and Ear Simulator 2cc couplers. The
Bruel & Kjaer 2cc DB-0138 (HA-2) coupler will simplify the calibration
procedure and is recommended. Reference thresholds for the DB-0138, IEC
711, and HA-1 couplers are presented below.
performed for an audiometer currently calibrated towards ISO-389, the
reference thresholds in a 2cc DB-0138 coupler should be used. In order to
calibrate the audiometer for direct readings of the hearing thresholds in dBHL
using the reference thresholds, the following procedure is recommended. The
instrumentation required is a Sound Level Meter with an appropriate
condenser microphone calibrated according to the manufacturer's
specification. To the microphone, a 2cc coupler, e.g., Bruel & Kjaer DB-0138
is attached. The white nylon tube nipple of the E-A-RTONE
connected directly to the coupler (see illustration). Set the intensity dial on the
audiometer to 70 dBHL and adjust the output from the audiometer to the SPL-
values given for the different test frequencies in the table below. Repeat the
procedure for all available test frequencies, and in case of a dual channel
audiometer, for both channels.
Case nipple
DB-0138 nipple
Frequency in Hz
125
250
500
750
1000
1500
2000
3000
4000
6000
8000
E-A-RTONE
Case
#13 tubing
DB-0138
2cc
coupler
ANSI S3.6-1996 and ISO 389-2:1994 Calibration Values
Coupler 2cc DB-0138
96.0
84.0
75.5
72.0
70.0
72.0
73.0
73.5
75.5
72.0
70.0
HA-1 COUPLER
Coupler IEC 711
98.0
87.5
79.5
76.0
75.5
79.5
81.5
83.0
85.0
86.0
85.5
6
Should calibration be
®
5A earphone is
E-A-RTONE
Case
E-A-RLINK
FUNTAK
Coupler 2cc HA-1
96.5
84.5
76.0
72.0
70.0
70.0
72.5
72.5
70.0
67.5
66.5
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