Acoustic Background

This section provides general background information on concepts relevant to fisheries acoustic surveys.  Additional information may be found in acoustic texts such as Simmonds and MacLennan (2005).  An introduction to acoustics is in Brandt (1996) and Rudstam et al. (in press).

Acoustic theory and use

Definitions, symbols and units

The SONAR equation

Introduction

General equation

Beam width or 3dB angle

The equivalent beam angle

Volume backscattering

Acoustic transducers

Beam pattern

Near-field and far-field

Target stength

Volume backscattering

Detection probability

Signal-to-noise ratio

Vessel noise and avoidance

Near surface and near bottom dead zones