A-A-54576
8. A complete bilateral test with a variable interstimulus interval shall take no longer than six minutes with a fully cooperative, normal hearing individual.
9. Stimulus characteristics:
a. Tone character: 1.2 seconds pulse train. Tone shall be on for 0.2 seconds and off for 0.2 seconds (50 percent duty cycle with three pulsed tone presentations). Rise and fall times shall correspond with values in ANSI S3.6.
b. Shall operate only in the pulsed tone mode.
c. Time between pulse trains shall vary randomly between one and two seconds.
d. Patient response window duration shall be 1.8 seconds. Window shall begin 50 milliseconds after the onset of the pulse train and end not less than 10 milliseconds before the onset of the following pulse train.
e. Pulse train shall terminate when the patient response switch is depressed.
f. Test paradigm shall be the modified Hughson – Westlake procedure as specified in ANSI S3.21-1978, paragraphs 4.1 (2) and 4.2. Threshold criteria shall be two responses at the same level after the initial response. Starting level shall be 30-40dB; if no response, increase level 20-30dB.
g. Shall retest at 1000Hz in both ears for plus or minus 5dB agreement with initial threshold.
10. Error warnings: Shall have visual error warnings and auditory signals to alert the technician to patient or test errors. The following error conditions shall be detected and signaled:
a. Threshold not established at 1000Hz, either ear.
b. Failure or retest at 1000Hz. Retest at 1000Hz shall be within plus or minus 5dB of initial test at 1000Hz. If not, test shall abort.
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