[ Back to EurekAlert! ] Public release date: 9-May-2011
[ | E-mail Share Share ]

Contact: Michael Bishop
michael.bishop@iop.org
44-117-930-1032
Institute of Physics

Bats lend an ear to sonar engineering

Researchers have mapped out the diversity of bat ears in a hope to inspire the design of new intuitive methods of manipulating waves with physical shapes, such as SONAR and RADAR.

Published today, Tuesday, 10 May, in IOP Publishing's journal Bioinspiration & Biomimetics, the study provides key insights into the variability of the shapes of bat ears that exists between different species, and shows how this variability may affect the functionality of one of the most impressive navigational systems in nature.

Bats are one of a few animal groups that demonstrate biosonar—the ability to generate and emit ultrasonic pulses and gauge the reflections to obtain detailed information on their surroundings.

Bats use biosonar as a way of navigating and hunting for food, however researchers have seen its potential to inspire new ways of engineering where manipulating outgoing or incoming waves with structures is a principal component.

Lead author Professor Rolf Müller, of Virginia Tech, said: "Using physical shapes to manipulate an outgoing or a received wave has application in many areas of engineering. Besides the obvious analogues of SONAR and RADAR, such principles could also find application in biomedical ultrasound, non-destructive testing, wireless communications, and sensory systems for autonomous robots and nodes in sensor networks."

The ear of a bat plays a crucial role in the overall sensing system by acting as a baffle to diffract the incoming waves therefore determining the ear's pattern of sensitivity to direction and frequency.

The researchers, working in a joint research laboratory of Shandong University and Virginia Tech, created 3D computer models of 100 bat pinnae—the visible part of the ear that resides outside of the head—from 59 different species, and transformed the models into cylindrical representations.

The representations were statistically analysed using principal component analysis—a method that has previously been applied to analyse human faces, palms, and ears —and were shown to vary in the opening angle of the pinna, breaks of symmetry between the right and left sides, and changes in width at both the top and bottom.

The researchers also demonstrated how this variability can affect the properties of beamforming—the process by which the incoming signal is diffracted by the shape of the pinna to create a "beampattern" through which the bat sees it environment.

The variability occurs as a result of the evolution of bats whose habitats range from environments with virtually no structures, to those with simple structures (calm water surfaces), to habitats with very complicated structures (dense forests).

The researchers found, for example, that a group of bats that hunts for prey in dense vegetation with trains of long, closely-spaced objects are separated from other bats by the widths of their pinna openings, demonstrating how biodiversity can provide a useful insight into how a general principal can be customised to fit different needs.

Professor Müller continued, "In order for this to happen, the ears of bats must be studied further. An example would be to expand the sample to include more diversity and find more specific relationships between pinna shape and beamforming across different species. Small local shape features that are hard to capture by the present analysis can also have a big impact on the function."

###

Notes to Editors

Contact

1. For further information, a full draft of the journal paper or contact with one of the researchers, contact IOP Press Assistant, Michael Bishop:
Tel: 01179 301032
E-mail: Michael.bishop@iop.org

A method for characterizing the biodiversity in bat pinnae as a basis for engineering analysis

2. The published version of the paper "A method for characterizing the biodiversity in bat pinnae as a basis for engineering analysis" (Bioinspir. Biomim. 6 026008) will be freely available online for 30 days from Tuesday 10 May. It will be available at http://iopscience.iop.org/1748-3190/6/2/026008

Bioinspiration & Biomimetics

3. Bioinspiration & Biomimetics publishes research which applies principles abstracted from natural systems to engineering and technological design and applications.

IOP Publishing

4. IOP Publishing provides publications through which leading-edge scientific research is distributed worldwide. IOP Publishing is central to the Institute of Physics (IOP), a not-for-profit society. Any financial surplus earned by IOP Publishing goes to support science through the activities of IOP.

Beyond our traditional journals programme, we make high-value scientific information easily accessible through an ever-evolving portfolio of community websites, magazines, conference proceedings and a multitude of electronic services. Focused on making the most of new technologies, we're continually improving our electronic interfaces to make it easier for researchers to find exactly what they need, when they need it, in the format that suits them best. Go to http://publishing.iop.org/.

The Institute of Physics

5. The Institute of Physics is a scientific charity devoted to increasing the practice, understanding and application of physics.

It has a worldwide membership of around 40 000 and is a leading communicator of physics-related science to all audiences, from specialists through to government and the general public. Its publishing company, IOP Publishing, is a world leader in scientific publishing and the electronic dissemination of physics. Go to www.iop.org



[ Back to EurekAlert! ] [ | E-mail Share Share ]

 


AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.