\1\ Table 1, in Sec. 325.7 is a tabulation of the maximum allowable sound level readings taking into account both the distance correction factors contained in Sec. 325.73 and the ground surface correction factors contained in Sec. 325.75.---------------------------------------------------------------------------
If the distance between the microphone location point and the microphone target point is other than 50 feet (15.2 m), the maximum observed sound level reading generated by the motor vehicle in accordance with Sec. 325.39 of this part or the numerical average of the recorded maximum observed sound level readings generated by the motor vehicle in accordance with Sec. 325.59 of this part shall be corrected as specified in the following table:
Table 2--Distance Correction Factors------------------------------------------------------------------------
The value
dB(A) to
be applied
to the
If the distance between the microphone location point and observed
the microphone target point is sound
level
reading
is--------------------------------------------------------------------------31 feet (9.5 m) or more but less than 35 feet (10.7 m)...... -435 feet (10.7 m) or more but less than 39 feet (11.9 m)..... -339 feet (11.9 m) or more but less than 43 feet (13.1 m)..... -243 feet (13.1 m) or more but less than 48 feet (14.6 m)..... -148 feet (14.6 m) or more but less than 58 feet (17.7 m)..... 058 feet (17.7 m) or more but less than 70 feet (21.3 m)..... + 170 feet (21.3 m) or more but less than 83 feet (25.3 m)..... + 2------------------------------------------------------------------------ [40 FR 42437, Sept. 12, 1975, as amended at 54 FR 50385, Dec. 6, 1989]