5
LI0039 – 5 July 2017
Introduction
This manual contains information about operating and calibrating the components of the
90AA and the 90AB. Due to their similarities, both products are described in this one
manual.
Both systems include the Audiometer System Calibrator HW1001. This portable system
makes acoustical measurements of frequency and levels of the test signal, as well as
harmonic distortion. The result table includes values for frequency of the test tone, level
of the test tone, LZeq, and harmonic distortion. These values are displayed together
with the 1/3 octave band spectrum.
The 90AA and 90AB Audiometer Calibration Systems comply with the following inter-
national standards:
• IEC 60318 Electroacoustics – Simulators of human head and ear - Part 1: Ear
simulator for the calibration of supra-aural earphones, 1998-07.
• ITU-T Recommendations P.57 (08/96) Series P: Telephone transmission quality,
Objective measuring apparatus: Artificial ears.
• ANSI S 3.7 – 1995 – American National Standard for Testing Earphones
The audiometers are calibrated with their supra-aural earphones, circumaural earphones,
and insert earphones. This is done with the couplers provided with the 90AA and 90AB.
• The supra-aural earphones TDH 39 and TDH 49 are standardized earphones
that require calibration with a 6cc coupler. These are also known as audiometric
earphones, headphones, headsets.
• The circumaural earphones HDA-200 are a standardized earphone that must be
calibrated with an ear simulator based on the IEC 60318 standard. HDA-200 is
also known as a high-frequency earphones, headphones, or headsets.
• Insert earphones, also known as ear inserts, are 3A and 5A. These are de-facto
standardized earphones, which can be calibrated with a 2cc coupler.
A typical calibration interval is once every other year. The calibration checks at each
frequency for distortion and calibrates the level.
The high-frequency coupler setup (43AA) has a test jig and an ear simulator (RA0039)
that is designed to follow the specifications of the IEC 60318-1 standard. The acoustic
input impedance of the RA0039 ear simulator closely resembles that of the human
ear. Therefore, it “hears”, or loads a sound source, in the same way as the human ear.
The adjustable spring-loaded arm of the test jig lets you carry out measurements under
well-defined conditions.
