Acoustic modelling of bat pinnae utilising the TLM method

This thesis describes the numerical modelling of bioacoustic structures, the focus being the outer ear or pinnae of the Rufous Horseshoe bat (Rhinolophus rouxii). There have been several novel developments derived from this work including: • A method of calculating directionality based on the sphere with a distribution of measuring points such that each lies in an equal area segment. • Performance estimation of the pinna by considering the directionality of an equivalent radiating aperture. • A simple synthetic geometry that appears to give similar performance to a bat pinna. The outcome of applying the methods have yielded results that agree with measurements, indeed, this work is the first time TLM has been applied to a structure of this kind. It paves the way towards a greater understanding of bioacoustics and ultimately towards generating synthetic structures that can perform as well as those found in the natural world

Measurement of a biomimetic antenna in the shape of a bat's ear

This paper presents a series of measurements of a novel antenna that physically resembles the ear of a bat. The antenna consists of a circular ground plane with a central monopole element. An equilateral triangular conducting plate is curved around the ground so that the base of the triangle is electrically connected to the perimeter of the circle and is of the same length. The input characteristic is reminiscent of a simple monopole above a circular ground, providing there are a sufficient number of modes in the triangular plate at the frequency of interest. In contrast to the plain monopole, certain frequencies yield a high gain and a radiation pattern with low side lobes. Measurements presented in this paper suggest that the antenna performance is broadly comparable with its acoustic analogue, although there are differences between the acoustic and electromagnetic implementation which have yet to be resolved

The measurement of the underwater radiated noise from a marine piling operation

Assessment of the underwater acoustic radiated noise during a marine piling operation was carried out in UK coastal waters in April 2006. A 2 m diameter, 65 m long test pile was driven into a "hard chalk‟ sediment. The pile was placed in an area of average water depth of 10-15 m approximately 3 km offshore