(Table 1) Age and depth of reflectors of the 3.5-kHz and airgun seismic record and their corresponding depth of ash layers, carbonate peaks, and transition zones from DSDP Hole 83-504B

DSDP cores from areas of low (Site 505) and high heat flow (Site 504 B) near the Costa Rica Rift, together with seismic profiles from the Panama Basin, have been studied to determine the relationship between: (1) carbonate content and physical and acoustic properties; and (2) carbonate content, carbonate diagenesis and acoustic stratigraphy. Except for ash and chert layers, bulk density correlates strongly and linearly with carbonate content. Velocity is uniform downcore and only small variations at a small scale are measured. Thus an abrupt change in carbonate content will cause abrupt changes in acoustic impedance and should cause reflectors that can be detected acoustically. A comparison of seismic profiler reflection records with physical properties, carbonate content and reflection coefficients indicates that the main reflectors can be identified with ash layers, diagenetic boundaries, and carbonate content variations. Diagenesis of carbonate sediments is present at Site 504B in a 260 m-thick ooze-chalk-limestone/chert sequence. These diagenetic sequences occur in areas of higher heat flow (200 mW/m**2). Seismic profiler records can be used to map the extent and depth of these diagenetic boundaries.

Truck noise IV-G. Field test results on a heavy duty, diesel truck having reduced noise emissions. Seventh report.

Transportation Department, Office of Noise Abatement, Washington, D.C.

Evaluation of ARMCO sound barriers on two bridges on I-495. Final report.

Virginia Department of Highways and Transportation, Richmond

Field study of a variable-height highway-noise barrier. Final report.

National Highway Traffic Safety Administration, Office of Research and Development, Washington, D.C.

An experimental and analytical investigation of the vibration noise generation mechanism in truck tires. Interim report.

National Highway Traffic Safety Administration, Office of Heavy Duty Vehicle Research, Washington, D.C.

An investigation of site effects on roadside measurement of truck noise. Final report.

Transportation Department, Office of Noise Abatement, Washington, D.C.

Development of standards and tests for acceptance of traffic signal lenses. Final report.

Federal Highway Administration, Washington, D.C.

Effects of load, inflation pressure and tire deflection on truck tire noise levels. Final report.

Transportation Department, Office of Noise Abatement, Washington, D.C.

Noise insulation of residences near freeways. Final report.

Mode of access: Internet.

Noise barrier attenuation: field experience. Final report.

Federal Highway Administration, Washington, D.C.

Static brake inspection investigation. Volume 3 - appendices. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Truck noise XI. Evaluation and reduction of heavy-duty truck noise. Final report.

Transportation Department, Office of Noise Abatement, Washington, D.C.

Roadside barrier effectiveness - noise abatement program. Final report.

National Highway Traffic Safety Administration, Office of Research and Development, Washington, D.C.

Noise and traction characteristics of bias-ply and radial tires for heavy duty trucks. Final report.

Transportation Department, Office of Noise Abatement, Washington, D.C.

Geographic variation in vocalisations of Satin Bowerbirds, Ptilonorynchus violaceus, in south-eastern Queensland

Geographic variation in the advertisement call of the male Satin Bowerbird, Ptilonorhynchus violaceus, was investigated in three populations in south-eastern Queensland. The call was found to differ significantly among the three geographically distinct populations. A discriminant function analysis using five measurements of call frequency and duration provided 100% classification success of the 25 individuals. The observed geographic variation in this call may result from adaptation to the local acoustic environment in these populations, or from genetic or cultural divergence among populations. Further research involving the acoustic properties of the habitats, population genetics and a larger number of populations is required to fully understand this pattern of call variation.