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Pre-Test Audiometric Checks (Version 3 and 4 only)
NOISE RECOVERY PERIOD
Exposure to high levels of sound (e.g., unmuffled lawn mowers, loud music, and gunfire) tends to
create a temporary threshold shift (TTS) which diminishes with time after exposure. Any
subject/patient tested soon after such exposure may exhibit a hearing loss that does not reflect his
or her normal hearing threshold. It is, therefore, important that the testing procedure prescribe some
time interval - usually at least 16 hours- between the last exposure to high-level sounds and the
administration of any hearing test.
ELIMINATION OF AMBIENT NOISE
At the time of purchase you chose your preferred style of acoustic transducer. If insert earphones
were selected you also chose your preferred ear coupling method, the EarCup or the Ear tip.
Excessive noise in the test environment during audiometric testing such as that produced by
conversation, typewriters, public address systems reduces test validity as it tends to mask the test
signals, particularly at the lower frequencies where earphone cushions provide less effective
attenuation. An acoustically treated room may be required if ambient noise reaches objectionable
levels (i.e., sufficient to cause apparent hearing loss at the low frequencies). Also, Audiocups are
available from GSI as an optional accessory. If the person being tested is in the same room as the
audiometer, it is recommended that he/she be seated about three feet (1 meter) away from the
instrument.
Maximum permissible noise levels are specified by the American National Standards
–
Criteria for
Permissible Background Noise during Audiometric Testing
, ears covered with earphones (S3.1 1991
revised). Table 3 shows the maximum background levels that can be present inside the room while a
valid hearing test is being conducted. For more comprehensive information about hearing testing and
hearing conservation, the user is referred to the Bibliography.
Frequency (Hz)
Test Room
Maximum dB SPL* in 1/3 Octave Band
125
29.0
250
17.5
500
14.5
750
16.5
1000
21.5
1500
21.5
2000
23.0
3000
28.5
4000
29.5
6000
33.0
8000
38.5
