A fly-inspired miniature microphone

Hypersensitive 2-millimeter-wide device could lead to a new generation of miniaturized low-power hearing aids

July 25, 2014

This is a top-side view in a microscope photograph of the biologically inspired microphone. The tiny structure rotates and flaps about the pivots (labeled), producing a voltage across the electrodes (labeled). (Credit: N. Hall/UT Austin)

University of Texas Austin researchers have developed a tiny prototype microphone device that mimics the Ormia ochraceafly’s hearing mechanism. The design may be useful for a new generation of hypersensitive, millimeter-sized, low-power hearing aids.

The yellow-colored Ormia ochracea fly, the inspiration for the design, can pinpoint the location of a chirping cricket with remarkable accuracy because of its freakishly acute hearing, which relies upon a sophisticated sound processing mechanism that really sets it apart from all other known insects.

Described in the journal Applied Physics Letters, from AIP Publishing, the 2-millimeter-wide device uses piezoelectric materials, which turn mechanical strain (from sounds) into electric signals that can be used to stimulate sensors in the inner ear. The use of these materials means that the device requires very little power.

“Synthesizing the special mechanism with piezoelectric readout is a big step forward towards commercialization of the technology,” said Neal Hall, an assistant professor in the Cockrell School of Engineering at UT Austin. “Minimizing power consumption is always an important consideration in hearing-aid device technology.

There are military and defense applications as well, and Hall’s work was funded by the Defense Advanced Research Projects Agency (DARPA). In dark environments, for instance, where visual cues are not available, localizing events using sound may be critical.

Super Evolved Hearing

Humans and other mammals have the ability to pinpoint sound sources because of the finite speed of sound combined with the separation between our ears. The spacing of several centimeters or more creates a slight difference in the time it takes sound waves to hit our ears, which the brain processes perceptually so that we can always experience our settings in surround sound.

Insects generally lack this ability because their bodies are so small that sound waves essentially hit both sides simultaneously. Many insects do detect sound vibrations, but they may rely instead on visual or chemical sensing to find their way through the fights, flights and forages of daily life.

O. ochracea is a notable exception. It can locate the direction of a cricket’s chirp even though its ears are less than 2 mm apart — a separation so slight that the time of arrival difference between its ears is only about four millionths of a second (0.000004 sec).

But the fly has evolved an unusual physiological mechanism to make the most of that tiny difference in time. What happens is in the four millionths of a second between when the sound goes in one ear and when it goes in the other, the sound phase shifts slightly. The fly’s ear has a structure that resembles a tiny teeter-totter seesaw about 1.5 mm long.

Teeter-totters, by their very nature, vibrate such that opposing ends have 180-degree phase difference, so even very small phase differences in incident pressure waves force a mechanical motion that is 180 degrees out of phase with the other end. This effectively amplifies the four-millionths of a second time delay and allows the fly to locate its cricket prey with remarkable accuracy.

Mimicking the Mechanism

The pioneering work in discovering the fly’s unusual hearing mechanism was done by Ronald Miles at Binghamton University and colleagues Ronald Hoy and Daniel Robert, who first described the phase amplification mechanism the fly uses to achieve its directional hearing some 20 years ago. In 2013, Miles, and his colleagues presented a microphone inspired by the fly’s ears.

Inspired by Miles’s prior work, Hall and his graduate students Michael Kuntzman and Donghwan Kim built a miniature pressure-sensitive teeter-totter in silicon that has a flexible beam and integrated piezoelectric materials. The use of piezoelectric materials was their original innovation, and it allowed them to simultaneously measure the flexing and the rotation of the teeter-totter beam. Simultaneously measuring these two vibration modes allowed them to replicate the fly’s special ability to detect sound direction in a device essentially the same size as the fly’s physiology.

This technology may be a boon for many people in the future, since 2 percent of Americans wear hearing aids, but perhaps 10 percent of the population could benefit from wearing one, Hall said.

“Many believe that the major reason for this gap is patient dissatisfaction, he added. “Turning up the gain to hear someone across from you also amplifies all of the surrounding background noise — resembling the sound of a cocktail party.”

The new technology could enable a generation of hearing aids that have intelligent microphones that adaptively focus only on those conversations or sounds that are of interest to the wearer. But before the devices become part of the next generation of hearing aids or smartphones, more design and testing is needed.

Abstract of Applied Physics Letters paper

The parasitoid fly Ormia ochracea has the remarkable ability to locate crickets using audible sound. This ability is, in fact, remarkable as the fly’s hearing mechanism spans only 1.5 mm which is 50× smaller than the wavelength of sound emitted by the cricket. The hearing mechanism is, for all practical purposes, a point in space with no significant interaural time or level differences to draw from. It has been discovered that evolution has empowered the fly with a hearing mechanism that utilizes multiple vibration modes to amplify interaural time and level differences. Here, we present a fully integrated, man-made mimic of the Ormia’s hearing mechanism capable of replicating the remarkable sound localization ability of the special fly. A silicon-micromachined prototype is presented which uses multiple piezoelectric sensing ports to simultaneously transduce two orthogonal vibration modes of the sensing structure, thereby enabling simultaneous measurement of sound pressure and pressure gradient.

references:

Michael L. Kuntzman, Neal Hall, Sound source localization inspired by the ears of the Ormia ochracea, Applied Physics Letters, 2014, DOI: 10.1063/1.4887370

HAROLD KESTER: A Great Gift to GOD

Two score and ten years ago I came to this nation dedicated to learning American culture, its way of life and its commitment to Liberty and the pursuit of happiness. 

I came as a foreign exchange student under the American Field Service (AFS) International Scholarship Program.

Showing me the way was an American family in Seal Beach, California - the Kester-Bauchwitz family. On hand to help was a classy group of teenagers identified as the Huntington Beach-Marina High School Class of 1964. 

Leading the group was Harold Kester, the high school’s Student Body President who eventually graduated as Class Salutatorian.

On Saturday, July 26, 2014, HB-Marina HS Class ‘64 will be celebrating its 50^th Anniversary.  I will be attending the celebrations while Harold Kester will not because he cannot. He joined the Lord on March 15, 2005 at the age of 58.

Harold was my foster brother. He belonged to the Kester-Bauchwitz clan who hosted me for one school year. He was the reason why AFS assigned me to live with them. We shared the same interest in student leadership and academics.  I was also Student Body President in my Philippine high school, and graduated Class Valedictorian.

A few days before graduation, he asked me for help in writing his speech as Class Salutatorian. This was because I had written and delivered a Valedictory Address before. I told him, “It is better if you write it from your heart. But it would be remembered more if you quote a hit song or a famous poem.”

He delivered one of the most memorable speeches I have ever heard. He quoted Robert Frost:

            “The woods are lovely, dark and deep.


            But I have promises to keep,


            And miles to go before I sleep,


            And miles to go before I sleep.” 

He went to California State Long Beach University majoring in Math ignoring scholarship offers from other colleges. Then, he proceeded to face the challenges of day-to-day life in a dual world – analogue and digital.  He conquered both. For his achievements, California State Long Beach University honored him as “Alumnus of the Year” in 1993.

I am unsure whether Huntington Beach – Marina High School has ever honored him.  But on this 50^th Anniversary of HB-Marina HS Class ’64, in my own little way, I am paying tribute to HAROLD KESTER.

Harold was not only a Mathematician who knew how numbers tell stories, he became an expert in information technology combining the use of computers and software engineering that offered advances in our “Planet of the Apps”.

Converting data to information; from information to intelligence; and from intelligence to knowledge and education was a natural process for him.  But artificial intelligence using the heuristic knowledge approach and robotics is another story.

In one of my visits to his office in Del Mar, California, he demonstrated to me the wonders of artificial intelligence and the future of consumer electronics.

In 1984, he founded the Del Mar Group which developed SmarTrieve, a search-and-retrieval program for electronic publishing. Recognizing its immense capabilities, Compton’s NewMedia, owned by Encyclopedia Britannica, bought Harold’s group in 1990.

Harold became NewMedia’s chief scientist and founded Britannica’s La Jolla Research Laboratory. He developed the world’s first multimedia CD-ROM encyclopedia and the first Internet-based encyclopedia.

My academic background and experience was following a different career path. But my exposure to Harold introduced me to a whole new world – the digital and electronic world.  That will have to be the subject of another article.

Nine years after being with Britannica, Harold joined Websense – a company that makes software used by large companies and the federal government to monitor and filter employees’ Internet use and protect against Web-based threats such as viruses and information theft.  Under his leadership, Websense produced the Explorer program, a Web-based browser reporting system that would allow an employer to check on an employee without having to ask its IT department to produce a report.

The contribution of Harold to the company was undeniable and significant. CEO John Carrington had recognized that Harold’s talents “made Websense what it is today.”

He emailed the employees, "Harold was never satisfied with existing ideas, or the current technology; he always knew he could do more,"

HAROLD KESTER: Amidst being an Excellent Software Engineer, a Creative Technology Pioneer, a Great Family Man, and an Efficient and Effective Management Leader; he was a Sharp Dresser, a Cool and Smooth Dancer, an Avid Sportsman, a Good Friend to many and most importantly, a Fun and Accommodating Foster Brother.

He will not be with us on Saturday, July 26, 2014. But as a Buddhist, he believed in Rebirth or Reincarnation - "the religious or philosophical concept that the soul or spirit, after biological death, begins a new life in a new body."  So he could be with us somehow!

In my religion, “What we are is a gift given to us by God. What we become is our gift to God.”  For what Harold had become, he was a great gift to God.

2014 & 2015 International CES at the Sin City

I attended the 2014 International CES held at Las Vegas, Nevada on January 7-10, 2014 as I did the previous CES events for several years.

I am very proud to say that I was an active participant in making it a record-breaking year for CES. The attendees and exhibitors enjoyed unique experiences and were exposed to new technologies and products many of which I described as “Magic, Miracle, and/or Mind-boggling”.  Most recently, I added “mystery” in the description.

Having attended this incredible technology event for over a decade as a credentialed member of the Press, I know whereof I speak. But for purposes of showing a more objective analysis of the 2014 International CES’ performance, I thought that I should cite the numbers coming from the AUDIT Report.

Here are some selected highlights:

First, the size of the Exhibit Space was large – 2.06 million net square feet.

Second, there were 160, 498 attendees.  Of these, 40, 828 were International attendees; 6, 575 Media; 2, 670 financial professionals, and 3, 673 Exhibitors.

Third, the Conference Sessions attracted 3, 987 attendees.

Fourth, 97,043 attended the exhibits only.

Sixth, there were 954 International Conference attendees.

Seventh, 1,878 represented the International Media.

Eighth, International visitors from 144 countries attended.

Ninth, 81% of the top consumer electronics retailers sent representatives.

Tenth, there were more than 20,000 products and technologies launched, displayed and demonstrated. 

Eleventh, the event attracted 146 U.S. government representatives led by The Honorable Penn Pritzker, Secretary of Commerce; 3 Members of the U.S. House of Representatives; the Chairman and 4 Commissioners of the Federal Communications Commission; other Federal officials from the Department of Transportation, Federal Trade Commission, and the U.S. International Trade Commission; and several U.S. State Elected Officials.

The 2015 International CES will be on January 6 – 9, 2015. It will also be held in Las Vegas, Nevada. It is expected that all the record numbers that I highlighted above will be broken in this coming event.

Registration for this event is now open.  I am encouraging our readers who are interested in consumer technology to attend the event.  If you intend to, I advise that you register now or before the end of August. 

Why? Registration prior to August 31, 2014 is FREE. Starting midnight of September 1^st, there is a $100 registration fee.  It will be $200 onsite.

By the time you read this column/blog, I would have already sent my registration.

When I said this event would produce new record numbers, I meant not just more attendance and larger exhibit space and therefore exhibitors but also because there would be more products and technologies that would be launched, displayed, and demonstrated.

Like in the past, due to time and human limitations, I will give priority to visiting the booths of products that would answer positively the question, “Is the product describable as Magic, Miracle, and/or Mind-Boggling?” Or even Mysterious?

I can’t wait!