IEC 60318-2:1998 pdf download – Electroacoustics – Simulators of human head and ear -Part 2: An interim acoustic coupler for the calibrationof audiometric earphones in the extended high-frequency range

IEC 60318-2:1998 pdf download – Electroacoustics – Simulators of human head and ear -Part 2: An interim acoustic coupler for the calibrationof audiometric earphones in the extended high-frequency range.
This part of IEC 60318 specifies two different adapters and the removable conical ring to be used with the IEC 60318-1 ear simulator to provide an interim acoustic coupler for the calibration of certain audiometric earphones designed for use in the extended high-frequency range from 8 kHz up to 16 kHz. Environmental conditions for the calibration and use of the coupler are given in IEC 60318-1.
2 Normative references
The following normative documents contain provisions which, through reference in this text. constitute provisions of this part of lEG 60318. At the time of publication, the editions indicated were valid. All normative documents are subject to revision, and parties to agreements based on this part of IEC 60318 are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. Members of lEG and ISO maintain registers of currently valid International Standard.
IEC 603 18-1 ,— Electroacoustics — Simulators of human head and ear — Part 1: Ear simulator
for the calibration of supra-aural earphones 1)
IEC 60645-4:1994, Audiometers — Part 4: Equipment for extended high-frequency audiometry
IEC 61094-1 :1992. Measurement microphones — Part 1: Specifications for laboratory standard microphones
IEC 61094-4:1995, Measurement microphones — Part 4. Specifications for working standard microphones
ISOITR 389-5:1998, Acoustics — Reference zero for the calibration of audiometric equipment — Part 5: Reference equivalent threshold sound pressure levels for pure tones in the frequency range8kHzto 16kHz
3 Microphone
The microphone in the lEG 60318-1 ear simulator shall conform to the dimensions of a Type LS2aP microphone given in IEC 61094-1 figure 1. For example, conformance may be achieved by replacing the protective grid of a Type WS2P (IEC 61094-4) microphone with an adapter ring so that this microphone with adapter ring conforms to the dimensions specified for Type LS2aP.
NOTE — It a grid is used, correction values should be stated for the difference between measurements with and without the grid.
4 Adapters for extended high-frequency measurements on an IEC 60318-1 ear simulator
Figure 1 shows the design of the Type 1 adapter and figure 2 the Type 2 adapter.
The dimensions and angles specified in figures 1 and 2 shall be met within tolerances of ±0,2 mm and ±2°, respectively.
The adapters shall be constructed of non-magnetic material.
5 Removable conical ring for the IEC 60318-1 ear simulator
The conical ring shall conform to the dimensions in figure 3 and should be made from a hard, non-magnetic material.
The dimensions and angles specified in figure 3 shall be met within tolerances of ±0,2 mm and ±2°, respectively.
6 Coupler configurations for the calibration of audiometric earphones in the extended high-frequency range
6.1 Coupler configuration using Type 1 adapter
For earphones designed to be calibrated by means of the Type 1 adapter, the IEC 60318.1 ear simulator shall be changed in the following manner:
— the conical ring of the ear simulator shall be removed and the Type 1 adapter placed on the ear simulator;
— the conical ring shall then be placed, non inverted, on top of the adapter as shown in figure 4,
The earphone shall be placed symmetrically on the coupler using a stated application force. Where an earphone has an asymmetrical cushion, the manner of placement on the coupler shall be stated by the manufacturer of the earphone.
6.2 Coupler configuration using a Type 2 adapter
For earphones designed to be calibrated by the Type 2 adapter. the lEG 60318-1 ear simulator shall be changed in the following manner:
— the conical ring of the ear simulator shall be removed and the Type 2 adapter placed on the ear simulator as shown in figure 5.
The earphone shall be placed on the coupler in such a way that it rests symmetrically on the distance clamps, as shown in figure 5, using a stated application force.