NOISE SOURCE LEVEL DENSITY DUE TO SURF .1. MONTEREY BAY, CA

Ambient noise measurements made in Monterey Bay, CA, in 1981 were redu ced by estimations of wave-breaking noise and the residual noise was c ombined with modeled transmission loss (TL) to estimate the spectral s ource level of surf-generated noise, A Hamilton geoacoustic model of t he coastal environment was derived and used in a finite-element parabo lic equation propagation-loss model to obtain TL values, Estimates of both the continuous, or local, and discrete components of wave-breakin g noise intensity were subtracted from the total measured noise held t o determine the contribution due to surf only, Surf breaking on a unif orm 12.5-km linear section of beach near Ft, Ord was found to be the d ominant source of surf-generated noise. Estimated noise source level d ensities for heavy surf at Ft. Ord beach varied from 138 dB ref. 1 mu Pa . Hz(-1/2).m(-1) at 1 m from the source at 50 Hz to 107 dB at 1 kHz , with a slope of about -5 dB per octave, Although these results must be considered as preliminary, since they are based on a small number o f measurements, they may be useful for prediction of ambient noise in other littoral regions.