Mode Colouration in Shallow-Water Ambient Noise,
Abstract
The spectrum of ambient noise observed in the shallow waters of the Bristol Channel shows a series of characteristic peaks, e.g. at 10, 28, 47 Hz etc. Up to six peaks have been seen, the frequency of each varying inversely with the water depth as the latter changes through the tidal cycle. Each peak corresponds to the cut-off frequency of one of the normal modes of sound propagation, since at this frequency there are ideally no losses due to coupling into either longitudinal or shear waves in the rock bottom. It is shown that information may be deduced on rock seismic velocity, sediment depth and the presence of gas at the sea-bed. The significance is discussed for theories of ambient noise, microseisms and acoustic transmission. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1970
- Accession Number
- AD0720591
Entities
People
- D. E. Weston
Organizations
- Admiralty Research Laboratory