SEC. 111.03. MINIMUM AMBIENT NOISE LEVEL. (Amended by Ord. No. 156,363, Eff. 3/29/82.) Where the ambient noise level is less than the presumed ambient noise level designated in this section, the presumed ambient noise level in this section shall be deemed to be the minimum ambient noise level for purposes of this chapter. TABLE II SOUND LEVEL “A” DECIBELS (In this chart, daytime levels are to be used from 7:00 a.m. to 10:00 p.m. and nighttime levels from 10:00 p.m. to 7:00 a.m.) PRESUMED AMBIENT NOISE LEVEL (dB(A)) ZONE DAY NIGHT A1, A2, RA, RE, RS, RD, RW1, RW2, R1, R2, R3, R4, and R5 50 40 P, PB, CR, C1, C1.5, C2, C4, C5, and CM 60 55 M1, MR1, and MR2 60 55 M2 and M3 65 65 At the boundary line between two zones, the presumed ambient noise level of the quieter zone shall be used.