(a) Training--Persons selected to measure vehicle sound levels shall have received training in the techniques of sound measurement and the operation of sound measuring instruments.

(b) Technician Positioning--The technician making direct readings of the meter shall be positioned in relation to the microphone in accordance with the instrument manufacturer's instructions. Where the instruction manual is vague or does not include adequate information, a specific recommendation shall be obtained from the manufacturer. The technician shall be no closer to the microphone than 1 m (3.3 ft) for new-vehicle tests and 0.6 m (2 ft) for highway and stationary tests.

(c) Bystander Positioning--During sound measurements, bystanders shall be no closer to the microphone or the vehicle being measured than the distance between the microphone and the microphone target point, except for a witness or trainee, who may be positioned behind the technician on a line with the technician and the microphone.