BS EN 60645-1:1995 Audiometers - Part 1. Pure-tone audiometers
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This part of International Standard IEC 645 specifies general requirements for audiometers and particular requirements for pure-tone audiometers designed for use in determining hearing threshold levels in comparison with the standard reference threshold level by means of psycho-acoustic test methods.
The purpose of this part is to ensure:
a) that tests of hearing, particularly threshold, on a given human ear performed with different
audiometers which comply with this part using methods described in ISO 8253-1 and ISO 6189 (see
clause 2) shall give substantially the same results;
b) that the results obtained represent a valid comparison between the hearing of the ear tested and
the reference threshold of hearing.
Audiometers can be classified in the following ways: according to the type of test signal they generate, according to the mode of operation or according to the complexity of the range of auditory functions they test (i.e. diagnostic, screening, etc.). However, in order to rationalize the classification of audiometers, five types are defined. Audiometers with which it is possible to make a diagnostic assessment (i.e. having as a minimum both air and bone conduction facilities) are classified as types 1, 2 and 3. Instruments with air con- duction facilities only are classified as types 4 and 5.
This part covers the general requirements for audiometers as a whole as well as their functional units: signal sources, signal level controls and transducers.
In addition, since the units specified cover the majority of audiometric applications, instruments which may not necessarily be conventional pure-tone audiometers and not specified in this part (such as an auditory stimulator for evoked potential recording), but which contain circuitry used for measurement of auditory sensitivity or presentation of supraliminal signals should, where possible, conform to the appropriate clauses of this part. By using table 1, the reader can find the appropriate clauses (5 to 9) of this part which describe the performance requirements for a given instrument.
