AS IEC 60645.1 pdf download – Electroacoustics—Audiological equipment Part 1: Pure-tone audiometers (IEC 60645-1:2001, MOD)

AS IEC 60645.1 pdf download – Electroacoustics—Audiological equipment Part 1: Pure-tone audiometers (IEC 60645-1:2001, MOD)

AS IEC 60645.1 pdf download – Electroacoustics—Audiological equipment Part 1: Pure-tone audiometers (IEC 60645-1:2001, MOD)
5.2Acoustic safety requirements
As audiometers are capable of producing sound pressure levels that could be damaging topeople with normal hearing a non-auditory warning indication to the operator is required for allhearing levels above 100 dB.
5.3Environmental conditions
The specifications shall be met for stated combinations of values of temperature within therange of 15 C to 35 C,relative humidity within the range of 30 % to 90 % and ambientpressure within the range of 98kPa to 104 kPa. The actual values of the environmentalparameters at the time of calibration shall be stated.
NOTE Reference equlvalent threshold sound pressure levels may differ significantly with ambient pressures
outside the above range.Therefore recalibration around the nominal ambient pressure at the site of the usershould be undertaken in those circumstances where the calibrationsite and the user site do not share similar
ambienf conditions.
5.4Warm-up time
The performance requirements shall be met after the stated warm-up time has elapsed andafter any setting up adjustments have been carried out in accordance with the manufacturer’sinstructions.The minimum warm-up time shall be specified by the manufacturer but shall notexceed 10 min when the audiometer has been kept at the ambient temperature of the testenvironment.
5.5 Power supply variation5.5.1Mains operation
The specifications shall be met when any long term deviation in supply voltage or mainsfrequency,in combination,is the least favourable within the limits of ±10 % of the statedmains supply voltage and i5 %of the stated mains frequency.
lf any complete interruption of the line voltage occurs up to 5 s, the audiometer shall revert toa condition that will neither endanger the subject’s hearing, nor yield invalid results.
5.5.2Battery operation
The manufacturer shall specify the limits of battery voltages within which the specifications
shall be met.A suitable indicator shall be provided to ensure that the battery voltages arewithin the specified limits. The specification of the audiometer shall be met at all battery
voltages within the specified limits.
5.6 lmmunity to power and radio frequency fields
5.6.1 Audiometers shall meet the requirements of IEC 60601-1-2 for electromagneticcompatibility (EMC).
5.6.2During,and as a result of,any EMC immunity testing, the following condition shall bemet:
under the EMC test conditions the unwanted sound from any air conduction transducershall not exceed a hearing level corresponding to 80 dB. Subclause 13.3 providesmethods for showing conformity.
5.7 Unwanted sound
5.7.1 General
Objective acoustical measurements may be impracticable for testing for the presence ofunwanted sound from the audiometer.Therefore,subjective tests shall be performed using atleast two otologically normal test subjects whose hearing threshold levels shall not exceed10 dB for the test frequencies 250 Hz to 8 kHz.The test room for subjective tests shall meetthe requirements of clause 12, table 4, right hand column of lSO 8253-1.
5.7.2Unwanted sound from an earphone
Unwanted sound from an earphone may arise from electrical signals generated in a variety ofways within the audiometer when the tone switch is “OFF”.An unwanted tone (commonlycalied breakthrough or cross talk) may also occur in the non-test earphone when the test toneis“ON”. Specific requirements and an indirect electrical measurement method are describedin and a subjective method of verifying performance is described in
An unwanted tone may also occur in the earphone due to the tone switch not beingcompletely effective.Requirements for the tone switch are described in 8.6.
5.7.3 Unwanted sound from a bone vibrator
The manufacturer shall state at which test frequencies the bone vibrator might radiate soundto such an extent that the sound reaching the test ear by air conduction through theunoccluded ear canal might impair the validity of the bone conduction measurement. Themanufacturer shall also state the possible extent of this impairment. A method to showconformity with this requirement is given in 13.4.2.
5.7.4 Unwanted sound radiated by an audiometer
Where audiometers are intended to be used with the subject in the same room,any sounddue to the operation of the audiometer controls during the actual listening test, or to radiationfrom the audiometer, or to radiation from any part of a computer system used in conjunctionwith the audiometer,shall be inaudible at each setting of the hearing level dial up to andincluding 50 dB.A method to show conformity with this requirement is given in 13.4.3.
NOTE The limitation on noise coming from controls applies to any noise that could furnish the patient with a cluewhich might influence the test results. it is not intended to apply to a mechanism such as an output selection switchor a detent on the frequency switch that might emit noise when the subject is not actually being tested.
5.8Testing of automatic recording and computer-controlled audiometers
Automatic recording and computer-controlled audiometers shall be provided with means toadequately control the signals for the purpose of measuring the characteristics of the audio-meter.