Featured Research

from universities, journals, and other organizations

Nanoscale 'tsunami' helps locusts tune in

Date:
November 6, 2013
Source:
University of Bristol
Summary:
The remarkable mechanism by which the tiny ears of locusts can hear and distinguish between different tones has been discovered by researchers. Understanding how the nanoscale features of the insect eardrum mechanically process sound could open up practical possibilities for the fabrication of embedded signal processing in extremely small microphones.

A locust with ion beam milling showing a section of eardrum.
Credit: Bristol University

The remarkable mechanism by which the tiny ears of locusts can hear and distinguish between different tones has been discovered by researchers from the University of Bristol.

Related Articles


Understanding how the nanoscale features of the insect eardrum mechanically process sound could open up practical possibilities for the fabrication of embedded signal processing in extremely small microphones.

Unlike a microphone membrane, the eardrum of the locust is a complicated structure which is used to process the information contained in an incoming sound. In order to survive, the locust needs to be able to distinguish between the friendly sounds of fellow locusts in its swarm and the sounds of a hunting bat approaching. These sounds differ in their tonal composition: locust sounds are raspy and noisy while bat echolocation calls have distinctly higher frequencies.

Using a set of laser beams shining on the locust, Dr Rob Malkin of Bristol's School of Biological Sciences and colleagues were able to observe the effects of incoming sound waves on the eardrum. They found that the locust eardrum behaved in a most unusual way, quite unlike a microphone membrane or the eardrums of other animals.

The researchers first confirmed a result the Bristol team observed a few years ago, namely that the eardrum generates concentric waves of vibrations that shoal in a tsunami-like fashion as they travel from one side of the membrane to the other. The new, detailed analysis shows that eardrum waves caused by low frequency sounds travel completely across the membrane, where low-frequency-sensitive nerve cells attach to the membrane. Remarkably, high frequency waves travel only half that far, and stop at the attachment point of high frequency neurons.

Using data and computer modelling, Dr Malkin, an aerospace engineer working in bio-inspired sensor research, quantified this mechanical behaviour. He said: "It rapidly became evident that the distribution of the vibrational energy was odd… quite unlike what normal materials do when waves travel through them."

The researchers then discovered a surprising effect: the energy density contained in the travelling wave was amplified as the wave travelled across the eardrum. The team measured that, as the high frequency waves converge onto one point, the amplification can be as high as 56,000 times. This energy localisation is remarkable because it is purely mechanical; at this stage only cleverly arranged material within the eardrum membrane does the job.

To understand how this effect is possible in such a small structure, the team used a combination of mathematical modelling with nanoscale measurements and structural visualisation. They employed a focussed ion beam at Bristol's Interface Analysis Centre to gain knowledge of the structural features of the locust's eardrum then fed this information into analytical models in order to unveil the contributions of different eardrum attributes. Thus, they established that a particular combination of attributes generates the phenomenon; geometry, tension, stiffness and mass distribution all turn the locust eardrum into a little mechanical processing device.

Professor Daniel Robert, who led the research team and is funded by the Royal Society, said: "Other animals, including mammals such as ourselves, analyse tonal differences using very refined mechanisms in the cochlea. Hearing in these animals is a three-step process, from capturing sound with an eardrum to amplifying vibrations through middle ear bones and then transmitting them to the cochlear frequency analyser. Locusts do not enjoy the luxury of such a complicated, large and biologically expensive to build apparatus. Instead their ears evolved to be much simpler with sound capture, local amplification and frequency analysis all taking place within one structure."

Dr Malkin added: "This is a feat of miniaturisation and simplification; we now need to make a similar sensor and test it."


Story Source:

The above story is based on materials provided by University of Bristol. Note: Materials may be edited for content and length.


Journal Reference:

  1. R. Malkin, T. R. McDonagh, N. Mhatre, T. S. Scott, D. Robert. Energy localization and frequency analysis in the locust ear. Journal of The Royal Society Interface, 2013; 11 (90): 20130857 DOI: 10.1098/rsif.2013.0857

Cite This Page:

University of Bristol. "Nanoscale 'tsunami' helps locusts tune in." ScienceDaily. ScienceDaily, 6 November 2013. <www.sciencedaily.com/releases/2013/11/131106073909.htm>.
University of Bristol. (2013, November 6). Nanoscale 'tsunami' helps locusts tune in. ScienceDaily. Retrieved April 25, 2015 from www.sciencedaily.com/releases/2013/11/131106073909.htm
University of Bristol. "Nanoscale 'tsunami' helps locusts tune in." ScienceDaily. www.sciencedaily.com/releases/2013/11/131106073909.htm (accessed April 25, 2015).

Share This


More From ScienceDaily



More Plants & Animals News

Saturday, April 25, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Dispute Flares Over Controversial Thai Temple Tigers

Dispute Flares Over Controversial Thai Temple Tigers

AFP (Apr. 24, 2015) Thai wildlife officials begin a headcount of nearly 150 tigers kept by monks at a temple which has become the centre of a dispute over the welfare of the animals. Video provided by AFP
Powered by NewsLook.com
College Kegger: University Gets in on Craft Brew

College Kegger: University Gets in on Craft Brew

AP (Apr. 24, 2015) Theres never been a shortage of beer on college campuses. But students at Cal Poly-Pomona are learning how to brew, serving their product to classmates, and hoping to land jobs in craft breweries when they graduate. (April 24) Video provided by AP
Powered by NewsLook.com
Cambodian Butterflies Help Villagers Make a Living

Cambodian Butterflies Help Villagers Make a Living

AFP (Apr. 24, 2015) Cambodia&apos;s Banteay Srey Butterfly Centre is the largest of its kind in Southeast Asia. As well as educating tourists about the creatures, it also offers a source of income to nearby villagers, who are paid to breed local species. Duration: 02:04 Video provided by AFP
Powered by NewsLook.com
3D Food Printing: The Meal of the Future?

3D Food Printing: The Meal of the Future?

AP (Apr. 23, 2015) Developers of 3D food printing hope the culinary technology will revolutionize the way we cook and eat. (April 23) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins