BS/EN 60645-1-2017 pdf download.Electroacoustics – Audiometric equipment Part 1: Equipment for pure-tone and speech audiometry (IEC 60645-1:2017).
The specifications shall be met for combinations of temperature within the range of 15 °C to 35 °C, relative humidity within the range of 30 % to 90 % and ambient pressure within the range of 98 kPa to 104 kPa.
The actual values of the environmental parameters at the time of calibration shall be stated.
Measured reference equivalent threshold sound pressure levels may differ significantly at ambient pressures outside the above range. Therefore calibration at the site of the user under their typical ambient pressure and temperature conditions should be undertaken. In circumstances where the calibration site and the user site do not share similar ambient conditions, appropriate corrections for environmental effects should be applied as recommended by the manufacturer.
5.4 Warm-up time
The performance requirements shall be met after the stated warm-up time has elapsed and after any setting up adjustments have been carried out in accordance with the manufacturer’s instructions. The minimum warm-up time shall be specified by the manufacturer but shall not exceed 10 mm when the audiometer has been kept at the ambient temperature of the test environment.
5.5 Power supply variation
5.5.1 Interruption of power supply
If any interruption of the power supply occurs for up to 5 s, the audiometer shall revert to a condition that will neither endanger the subject’s hearing, nor yield invalid results.
5.5.2 Mains operation
The specifications shall be met when any long-term deviation in mains supply voltage or frequency, in combination, is the least favourable within the limits of ± 10 % of the stated mains supply voltage and ± 5 % of the stated mains frequency.
If any complete interruption of the line voltage occurs up to 5 s, the audiometer shall revert to
a condition that will neither endanger the subject’s hearing, nor yield invalid results.
5.5.3 Battery operation
The manufacturer shall specify the limits of battery voltage within which the specifications shall be met. A suitable indicator shall be provided to ensure that the battery voltage is within the specified limits. The specification of the audiometer shall be met at all battery voltages within the specified limits.
5.7.1 General
Objective acoustical measurements (see 13.4) may be impracticable for testing for the presence of unwanted sound from the audiometer. Therefore, subjective tests shall be performed using at least two otologically normal test subjects whose hearing threshold levels shall not exceed 10 dB for the test frequencies 250 Hz to 8 kHz. The test room for subjective tests shall meet the requirements of ISO 8253-1:2010. Table 4 (see the right hand column of table). For EHF audiometers these tests shall cover frequencies up to the highest frequency available.
NOTE For the frequency range above 8 kHz test rooms according to ISO 8253.1 have shown in practice to provide suff;ciently low ambient noise levels
5.7.2 Unwanted sound from and between any combination of transducers
The following measurements shall be completed by the manufacturer as part of an audiometer design validation to ensure the intended requirements of 5.7 are met in any combination of transducers. Testing shall be conducted for crosstalk, breakthrough or leakage between or from all transducers, for example: earphones, insert earphones, bone vibrator, loudspeakers, or monitors. Any unwanted sound present in any non-active transducer shall be less than 0 dB HL. This shall be measured in one-third-octave bands throughout the full test capability provided by the audiometer. The unwanted sound present in any one-third-octave band shall not exceed the reference sound pressure levels or force levels, specific for each non active transducer measured. Measurements shall be made electrically.
This requirement shall be met with all selected active transducers signals switched on, set to a hearing level of 60 dB or maximum output whichever is lower. The electrical indirect measurement method shall be used to validate performance as described in 13.4.1.
5.7.3 Unwanted sound from an earphone
Unwanted sound from an earphone may arise from electrical signals generated in a variety of ways within the audiometer when the signal switch is HOFF”. An unwanted tone (commonly called breakthrough or cross talk) may also occur in the non-test earphone when the test tone is “ON. Specific requirements and an indirect electrical measurement method as well as a subjective method of verifying performance shall be employed as described in 13.4.1.
An unwanted tone may also occur in the earphone due to the signal switch not being completely effective. Requirements for the signal switch are described in 8.6.
5.7.4 Unwanted sound from a bone vibrator
The manufacturer shall state at which test frequencies the bone vibrator might radiate sound to such an extent that the sound reaching the test ear by air conduction through the unoccluded ear canal may affect the reliability of the bone conduction measurement. BS/EN 60645-1-2017 pdf download.