This document provides an overview of converting sound energy to electricity. It discusses piezoelectric crystals and Sonea devices that can directly convert sound into electricity. Acoustic sound harvesting is described as the process of capturing sound energy, storing it, and controlling it for small devices. An experiment conducted in London successfully harvested the power of footfall and generated electricity. Potential applications of this conversion technique include powering small devices and sensors. While it can utilize wasted sound energy, limitations include low power densities of sound waves.

1. A
REPORT
ON
SOUND ENERGY AND ELECTRICITY
BY
ADRITA MAJUMDER, ECE1 08
A REPORT SUBMITTED IN PARTIAL FULLFILLMENT OF THE
REQUIREMENTS OF
HU481: TECHNICAL REPORT WRITING
13TH MARCH 2014-02-27
ACADEMY OF TECHNOLOGY
AEDCONAGAR, HOOGHLY- 712121

2. CERTIFICATE BY THE SUPERVISORS
S.CHATTERJEE
Assistant Professor, Department of Engineering Science and Humanities,
Academy Of Technology, Adisaptagram
S.CHATTERJEE
Assistant professor, department f engineering science and humanities
Academy of technology, Adisaptagram
This is to certify that technical report entitled sound energy and electricity is a document of
work done by Adrita Majumder under our supervision during the period January 2014 to
march 2014
...........................................
S.CHATTERJEE
............................................
S.CHATTERJEE

3. STATEMENT BY THE CANDIDATE
Adrita Majumder
B.Tech 4th Semester
Department of ECE, Roll Number 08
Academy Of Technology
I hereby state that the technical presentation entitled sound energy and electricity has been
prepared by me to fulfill the requirement of HU481 during the period January 2014 to March
2014.

4. ACKNOWLEDGEMENT
I would really like to thank every person who has helped to complete my report successfully.
All the websites where I have taken help from. All my friends who have helped to chose this
topic and collect every bit of information about the topics. A special thanks to my best friend
Rajarshi without whom completion of this very report would have been just impossible.
Definitely my parents and my professors are worth mentioning who have kept supporting me
throughout and have kept faith that I could do it.

5. ABSTRACT
We all are well aware of the crisis of electricity that we, the present generations are facing. If
we can ‘non -technically’ define what sound energy is, we would say it is the most neglected
form of energy which is only considered to be a wastage. But the actual scenario is a bit
different. Since the population explosion the consumption of food, space has increased. So
has increased the consumption of electrical energy. But as we all are well known to the
theorem of energy conservation- Energy can neither be created nor be destroyed, it can be
converted from one form to another. So here we change the energy which is commonly
available – sound to the energy which our world is scarce of – electricity.
Since we are actually talking about the conversion of a form of energy to the other, we must
remember that the conversion of energy is in accordance with the law of conservation of
energy – energy can neither be created nor be destroyed, it can be changed from one form to
the other. Chapter 1 deals with the various devices like piezoelectric crystal transducer, sonea
converts the sound energy to electrical energy. their exact structure and function has been
clearly defined. Chapter 2 deals with the acoustic sound harvesting that is the way by which
sound converted to electricity can be stored and utilised in future. Chapter 3 gives us a real
life experiment where sound energy was harvested in London and from that harvested sound
electricity was generated. In chapter 4 the various applications of this conversion of sound
energy to electrical energy has been discussed. How the various application of this technique
will make our life-style easier is seriously dealt with. Chapter 5 talks about the merits and
demerits of using this conversion technology.
Finally we conclude that after population explosion, since the consumption of electricity has
been increasing, there is an utter lack in the resources which produce electricity. So sound
energy conversion to electricity is one of the best measures that can give the permanent
solution to the lack of electricity, in this generation.

6. LIST OF FIGURES
Fig 1.1 Is It Possible To Convert Sound Energy To Electricity
Fig 2.1 Piezoelectric Crystal
Fig 2.2 SONEA
Fig 4.1 The Power Of Footfall Being Harvested In London Olympic Games
Fig 5.1 Sound Conversion Into Electromagnetic Energy
Fig 5.2 Transducer Chip In Human Heart
Fig 5.3 Piezo Electric Crystal Transducer
Fig 7.1 Schematic Representation Of Energy Conversions

7. TABLE OF CONTENTS
TITLE PAGE NUMBER
Certificate by the supervisors i
Statement by candidate ii
Acknowledgement iii
Abstract iv
List of figures v
Introduction 1
Devices that convert sound energy to electricity 2
Acoustic sound harvesting 4
Harvesting the power of footfall 5
Applications 6
Advantages and disadvantages of the conversion technique 8
Conclusion 9
Bibliography 10

8. INTRODUCTION
Converting sound into electricity works on a simple mechanism. If heat is applied to any
enclosed area, the air inside it expands increasing the pressure inside. This pressurized air,
then moves through a filter or opening on one side, producing a simple clear sound at a
standard frequency. That is the basic idea behind the system. Focused and directed frequency
makes it easier to extract energy.
Well, not quite, however good old-fashioned sound just might do the trick thanks to the work
by University of Utah Physicist Orest Symko and his students who have developed a way to
turn excess heat into sound and electricity. If it sounds too good to be true, well then you
might be surprised to hear that it actually works! It works via a very simple and well known
process. If you take a source of heat and apply to any enclosed area, the air inside it will
expand increasing the pressure inside. This pressurized air will then move through a filter or
opening on one side, producing a simple clear sound at a standard frequency. That’s the key
to the system. The more focused and directed the frequency is, the easier it is to extract energy
from.
We all know sound energy is a mechanical energy which travels in the form of wave.
Longitudinal waves are of alternating pressure deviation from the equilibrium pressure,
causing local region of compression and rarefaction, while transverse wave (in solid) are
waves of alternating shear and stress at right angle to the direction of propagation. When
sound wave travel through a medium mater in that medium is periodically displaced and thus
oscillates with sound wave. The sound wave displace back and forth between the potential
energy of compression or lateral displacement strain of the matter and the kinetic energy of
the oscillation. As sound energy is a mechanical energy it could be converted into electricity
as mechanical energy could be converted into electricity by the law of thermodynamics.
FIG 1.1 IS IT POSSIBLE TO CONVERT SOUND ENERGY TO ELECTRICITY?

9. DEVICES THAT CONVERT SOUND ENERGY TO ELECTRICITY
Piezoelectric are materials capable of turning mechanical energy into electricity, and can be
substances as simple as cane sugar, bones, or quartz. Much research in this field has been
focused on transforming the movement of a person running, or even the impact of a bullet,
into a small electrical current, but although these advanced applications are not yet available
in consumer products, scientists have been using piezoelectric materials in environmental
sensors and speakers for years.
FIG 2.1 PIEZOELECTRIC CRYSTAL
The Korean researchers were interested in reversing this process however. "Just as speakers
transform electric signals into sound, the opposite process - of turning sound into a source of
electrical power - is possible," said Young Jun Park and Sang-Woo Kim, authors of the article
in journal Advanced Materials.
Piezoelectric create an electrical charge under stress, and thus zinc oxide, the main ingredient
of calamine lotion, was bent into a field of nano wires sandwiched between two electrodes.
The researchers subjected the sandwich to sound waves of 100 decibels which produced an
electrical current of about 50 milli-volts.

10. FIG 2.2 SONEA
Sonea are devices which can convert sound energy to electricity. This a bit different from the
other devices because this not only converts sound energy to electricity but also that it has a
cell which can store the electricity for future use. Not always do we need the entire electricity
created so it is sometimes necessary to store the energy so that it can be used whenever we are
lacking electricity.

11. ACOUSTIC SOUND HARVESTING
Acoustic energy is generated and unused all around us. Whether it is the constant hum of an
HVAC unit behind a building, an airplane taking off at the airport or a train departing the
station, acoustic energy is cast off as a nuisance or ear sore. Most of these locations try to
absorb as much of this energy as possible or are in remote locations so that their customers do
not have to be susceptible to the high amount of noise. But with the large focus on 'green
energy' as of late, efficiency and harnessing all possible forms of energy has come to the
forefront and the loss of any type of energy has become a sin.
Acoustic energy harvesting is the process by which energy is derived from external noise
sources, captured, stored, and controlled for small wireless autonomous devices. Acoustic
energy harvesting is not as popular as the other types of energy harvesting method since
sound waves have lower power density. However, in this age of efficiency and alternative
energy sources research, acoustic energy harvesting has become something that can't be
overlooked since it is one of the vastly available energy sources. From the initial stages of this
project, we have managed to finish up the final draft for the product design. During these
phases, the goal was to develop the specifications for a small device that could harness energy
from ambient noise and convert it into usable electrical energy. The main focus during this
portion of the project was on technical research, theoretical calculation, and data acquisition
in order to determine the best combination that yielded the best results.
AOUSTIC ENERGY HARVESTING DEVICE
The device was model based on the Side Branch Helmholtz Resonator, which consists of a
neck, cavity chamber, and membrane attached at the end of the chamber. The membrane is
connected to piezoelectric material that converts the vibrations caused by the sound into
electrical energy. This energy will then be directed to a storage device that will be capable to
autonomously stored. As for the storage device, we will be using CYMBET CBC EVAL 09
Ener Chip CP, an energy harvesting evaluation board that can track and measured the energy
generation while at the same time having the ability to store and channelled the collected
energy.

12. HARNESSING THE POWER OF FOOTFALL
Endless amounts have been written about what is the right path to a low-carbon future – but
not much of that commentary has focused on the role that literal paths could play. Yet in the
future we may all be generating energy wherever we go, whether we're walking, driving or
sitting on the train, using a technique known as energy-harvesting.
There are two main approaches. One is to use mechanical technology to capture the energy
and convert it into electricity and the other is to use piezoelectric materials, which produce
electricity when they are put under pressure – when someone steps on them or drives over
them, for example. One of the best-known uses of the technique was in a club in Rotterdam,
which installed an energy-generating dance floor, where the dancers created their own light
show. While in the UK, a company, Pavegen, has generated energy from schoolchildren
running to their next lesson, from thousands of runners at this year's Paris Marathon, revellers
at the Bestival music festival on the Isle of Wight and spectators travelling to watch the
London 2012 Olympic Games via West Ham tube station. The technology is ideal for
anywhere that attracts crowds, so ticket barriers at train and tube stations are an obvious
application, but the concept will also work at shopping centres, sports venues, even airport
terminals. And as a technique that produces more energy when more people travel across the
energy-producing materials, it's a particularly elegant solution to matching supply with
demand. As well as harnessing the power of pedestrians, energy harvesting also works well in
roads and on rails. Innowattech, has been conducting tests on embedding piezo-materials into
roads and railways to generate energy as vehicles pass over them, which is then stored in
batteries which can be used to power roadside lights or feed into the grid.
FIG 4.1 THE POWER OF FOOTFALL BEING HARVESTED IN LONDON OLYMPIC
GAMES

13. APPLICATIONS
Researchers in Japan and Germany have converted energy from sound waves into
electromagnetic energy, trapping a magnetic "spin current" between metal layers. In the
experiment, when sound waves are directed at an interface between the thin metal layer and
magnetic material, electrical signals are generated at a pair of electrodes attached above.
When the sound waves reach the magnetic material, this creates a spin current that gets picked
up by three layers of metal. This is where the exercise class-sounding reverse spin Hall effect
kicks in, transforming it into an electrical voltage.
FIG 5.1 SOUND CONVERSION INTO ELECTROMAGNETIC ENERGY
Recent exeperimentations have come to a conclusion that our own heart beat can chanrge our
phone. An experiment was performed in Russia where a transducr chip was surgically
implemented in the heart of a human being. The lubb and dupp sounds of the heart creates
sonic vibrations which by external circuitry can charge a phone.

14. FIG 5.2 TRANSDUCER CHIP IN HUMAN HEART
Not only this, but also a phone with a piezo electric crystal transducer can convert sound
energy into electricity and charge a phone. A piezo electric crystal transducer delivers electric
power by converting sonic waves into electricity and hence it can charge a phone. So
basically talking over th mobile phone charges it.
FIG 5.3 PIEZO ELECTRIC CRYSTAL TRANSDUCER

15. ADVANTAGES AND DISADVANTAGES OF CONVERSION OF SOUND
TO ELECTRICITY
MERITS
 As sound has enormous amount energy with it, it could be used by converting it into
electric energy for various purposes
 Sound energy is a mechanical energy so according to law of thermodynamics
mechanical energy could be converted into electric energy
 Sound energy could be converted by different methods by creating apparatus using
curtain (diaphragm) magnet and conductor ,by converting Sound energy to heat
energy and then heat energy to electric energy ,by using transducers such as
piezoelectric material which converts mechanical strain to electric energy and vice4
versa
 Piezoelectric crystals are the crystals which converts mechanical strain to electric
energy
 The strain applied to piezoelectric material by sound energy could be converted into
electricity
 In this aspect lot of research is to be done but on a positive note this could surely be
done which could solve the energy problem of the entire world
DEMERITS
 Lots of work is to be done in this field.
 Its efficiency is not that good so improvement is being required.
 It is bit costlier as a whole setup would be done.
 It could not be used in the places where decibel of sound is very low.

16. CONCLUSION
Researcher Dr. Sang-Woo Kim said, "The sound that always exists in our everyday life and
environments has been overlooked as a source. This motivated us to realise power generation
by turning sound energy from speech, music or noise into electrical power. Currently, the
researchers have created a prototype that converts sounds around 100 decibels (think: noisy
traffic) to 50 milli-volts of electricity. Here's how it works: a pad absorbs sound waves and
causes zinc oxide wires mounted between electrodes to compress and release, creating an
electrical current that can be used to charge a battery. Fifty milli-volts isn't enough to charge a
mobile phone, but Dr. Kim said that the technology could be improved by using different
materials. Fortunately, the current prototypes create enough energy to be usable in small, low-
power sensors and implantable devices
FIG 7.1 SCHEMATIC REPRESENTATION OF ENERGY CONVERSIONS
If we will be able to convert sound energy to electric energy efficiently it could help us to
reduce the scarcity of electrical energy globally and help in the development of mankind and
reduction of CO2 as electric energy is one of the cleanest energy. The noise pollution in the
road would be able to convert into electric energy and lights the street lighting, signals and
various other electrical appliances. The noise pollution in runway could be used to produce
electricity. The electricity produce in nuclear power station could increase as the sound
produce during nuclear fission also could be used to get more electric energy. The noise
pollution in industries could be used to produce electricity and work certain low voltage
machine its scope doesn’t end.

17. BIBLIOGRAPHY
[1] “Piezoelectricity”, Wikipedia, The Free Encyclopedia, Wikimedia foundation, 2006,
http://en.wikipedia.org/wiki/Piezoelectricity, 24/01/2014.
[2] “Transducer”, Wikipedia, The Free Encyclopedia, Wikimedia foundation, 2006,
http://en.wikipedia.org/wiki/Transducer, 24/01/2014.
[3]“Sonea”,http://www.yankodesign.com/2009/09/09/sonea-converts-sound-to-energy/,
26/02/2014.’
[4] “Researchers convertsoundwavesintoelectromagneticenergy,silence nolongergolden’’ ,
http://www.engadget.com/2011/09/20/researchers-convert-soundwaves-into-electromagnetic-
energy-sile/, 28/02/2014.