Accession Number : ADA265128


Title :   The Curtain Effect in a Multiple Convergence Zone Environment: Part 1. Implications for Ambient Noise.


Descriptive Note : Technical rept.,


Corporate Author : NAVAL UNDERWATER SYSTEMS CENTER NEW LONDON CT


Personal Author(s) : Browning, David G ; Christian, Raymond J


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a265128.pdf


Report Date : 24 Jan 1991


Pagination or Media Count : 19


Abstract : Over multiple convergence zone propagation ranges the relative spreading loss per zone, although initially high, decreases with range. The other major component of propagation loss, attenuation, remains unchanged and eventually becomes greater than the rate of spreading loss. The range at which this crossover occurs is highly frequency dependent. At low frequencies the curtain effect occurs at long ranges; this allows sources or scatterers in the second convergence zone or beyond to impact the received level since they suffer only a relatively small additional loss compared to the spreading loss to the first convergence zone. For a given distribution of noise source levels or scattering strengths it is estimated what would be the resulting background level and the relative importance of events, for example, a comparison between medium strength multiple events at medium ranges and a strong event at long range. This analysis is then extended to higher frequencies where the curtain effect occurs at a range of one convergence zone or less.


Descriptors :   *ACOUSTIC ATTENUATION , *AMBIENT NOISE , PROPAGATION , ACOUSTICS , CONVERGENCE ZONES , TRANSMISSION LOSS , ACOUSTIC SCATTERING , LOSSES


Subject Categories : Acoustics


Distribution Statement : APPROVED FOR PUBLIC RELEASE