Register to reply

Converting noise into electrical energy

by kthouz
Tags: convert, electric, energy, noise, piezo
Share this thread:
Alinoonva
#91
Jul19-12, 12:47 PM
P: 2
Hi all,

I have been interested in the conversion of sound into electrical energy as well. I have been reading everyones post about this and how it is seemingly impossible or yet not efficient to convert sound energy into electricity. I am not a physicist but I do study biology and the human ear basically converts sound into electrical signals which are then interpreted by the brain. What I am interested in is understanding how to measure whether this is an energy consuming process (some sort of amplification which I dont think it is) or not. If it is not energy consuming that the largest problem is physically bringing dissipated sound from a large area into a small condensed area where it can create mechanical motion.

The ear takes sound from a large space (via the outer ear) and then propagates that sound through the auditory canal into a smaller more condensed space and causes vibration to the tympanic membrane which causes vibration of the malleus incus and stapes connected to the fluid filled cochlea. Inside the cochlea there are hair like cells... the vibration of the fluid moves these hair like cells (mechanical energy) and that movement is converted into nerve impulse and sent to the brain via the cochlear nerve.

I know this is possible I would really appreciate some help as how to create measurement protocols so I can assess this.
sophiecentaur
#92
Jul19-12, 01:06 PM
Sci Advisor
PF Gold
sophiecentaur's Avatar
P: 11,873
There is an essential difference between detection of signals and using them as a source of energy. The ear, along with all other detection systems (ignore the crystal set), has the job of detecting very low levels of sound signal energy and uses energy from the body to transform this signal into a form that can be used by the brain. The body has to expend energy (from food) to achieve this.

If you want to 'harvest' energy, you can't use amplifiers but you need enough energy for the harvesting system to drive itself and have a worthwhile amount left over. (Otherwise the system is a waste of time and energy). In nearly all circumstances, the flux of sound energy is too low to make harvesting worth while - it would involve deadly levels of sound. If you are talking 'total cost', it is far better to make machinery more efficient so it produces less (wasted) noise energy in the first place. That is a much better engineering solution in most cases.

I guess there may be viable applications for powering very low power devices from available sound energy, because this makes them 'wireless' and they don't need a feed of power from elsewhere. (A bit like the popular solar / wind driven remote systems we are starting to see all over the place.) But the sound levels required are extremely high if you want even just a few miliWatts of usable power. In some cases, you'd find that the total energy put into building the installation could be more than the total energy it can ever supply. It's a possible answer to localised power requirements but we will never 'save the planet' with such sound energy harvesting. (No point in putting one in front of your TV, for instance)
Alinoonva
#93
Jul19-12, 01:54 PM
P: 2
Thanks for the reply. Are you sure that the body's conversion of sound to electric signal is done using energy?

What is the crystal set?

Your reasoning for not harvesting sound: I understand sound in large space is useless but what if sound was culminated from a large area and then transferred into a very small dense area? For example if we accumulate sound from cars made within a tunnel and guided it to a very small area (almost like a funnel) would we be able to create mechanical energy at the smaller end of that funnel? Or do you still think it is far too small of a number?
sophiecentaur
#94
Jul19-12, 02:30 PM
Sci Advisor
PF Gold
sophiecentaur's Avatar
P: 11,873
Quote Quote by Alinoonva View Post
Thanks for the reply. Are you sure that the body's conversion of sound to electric signal is done using energy?

What is the crystal set?

Your reasoning for not harvesting sound: I understand sound in large space is useless but what if sound was culminated from a large area and then transferred into a very small dense area? For example if we accumulate sound from cars made within a tunnel and guided it to a very small area (almost like a funnel) would we be able to create mechanical energy at the smaller end of that funnel? Or do you still think it is far too small of a number?
Oh boy. You must be soooo young! It was the first type of Radio receiver that enthusiasts used. It consisted of a tuned circuit and a rectifier diode (crystal) with no amplification, that fed a sensitive pair of headphones.

Can you imagine the cost of a suitable funnel, fitted into the side of a tunnel? It would need to have a vast opening and have a long enough taper to match the sound into a suitable transducer. To justify it, you would need actual figures for the likely energy return. How much sound energy flux do you think there is in a tunnel full of cars? You wouldn't get more than that out even if the system were 100% efficient. This is a hard nosed engineering problem which can't be assessed by just arm-waving.
ramganesh
#95
Jul29-12, 08:49 AM
P: 1
As sound energy is not sufficient for producing large amount of electrical energy
ie.,80db=1milla watt so why dont we go for energy amplifiers having 10^6 gain
nasu
#96
Jul29-12, 09:05 AM
P: 1,970
Quote Quote by ramganesh View Post
As sound energy is not sufficient for producing large amount of electrical energy
ie.,80db=1milla watt so why dont we go for energy amplifiers having 10^6 gain
One reason may be that energy amplifiers do not exist so far.
sophiecentaur
#97
Jul29-12, 11:38 AM
Sci Advisor
PF Gold
sophiecentaur's Avatar
P: 11,873
Quote Quote by ramganesh View Post
As sound energy is not sufficient for producing large amount of electrical energy
ie.,80db=1milla watt so why dont we go for energy amplifiers having 10^6 gain
An "amplifier" requires a power supply. That power supply would need to provide the extra 99999extra mW. Where would that come from? Answer: the mains electricity supply and not the traffic noise.

When people try to come up with solutions to Engineering problems, they really should apply some of the discipline that Engineering demands. Rule number one: you don't get 'owt for nowt.
Dek
#98
Jul30-12, 05:16 PM
P: 1
Surely we're looking at this from the wrong perspective. When sound is produced this is energy from it's dissipation. We should be thinking about harnessing energy at the point of sound being created. The best place to do this is in looking at waves, and picking up the energy before it dissipates against the rocks and sand.
sophiecentaur
#99
Jul30-12, 06:38 PM
Sci Advisor
PF Gold
sophiecentaur's Avatar
P: 11,873
The best approach is to reduce the amount of noise produced in the first place. It's about making more efficient systems.
Mahipat Singh
#100
Aug4-12, 05:47 AM
P: 6
Researching on clouds methodology, where i am getting lot of sounds and electricity, this will help me to produce huge amount of sound into electricity.
sophiecentaur
#101
Aug5-12, 05:57 AM
Sci Advisor
PF Gold
sophiecentaur's Avatar
P: 11,873
What constitutes a "huge amount"? 1W, 1MW? If you can't answer that then you have no answer to any of this.
nydhruv
#102
Aug28-12, 02:00 PM
P: 1
I read that sound absorbing material absorb the sound waves and store it in the form of energy, usually heat. Will it be possible to store this energy through some mechanism over a period of time and then use when there is a requirement?
sophiecentaur
#103
Aug28-12, 02:56 PM
Sci Advisor
PF Gold
sophiecentaur's Avatar
P: 11,873
Why do people ignore the QUANTITIES involved? Is this not the whole crux of this topic??? Does the amount of energy involved not strike you as relevant?
Bobbywhy
#104
Aug28-12, 05:03 PM
PF Gold
P: 1,880
nydhruv, Welcome to Physics Forums!

Your suggestion to store heat from the absorption of acoustical energy makes no sense. Did you read sophiecentaur's post(s) above? Do your maths. The AMOUNT or QUANTITY of this heat, if you calculate it, will be tiny, miniscule, infinitesmal, and hardly measurable.
LastTimelord
#105
Aug28-12, 05:08 PM
P: 32
Noise is not a very large amount of energy at all. If a person were to scream as loud as they could for 5 years, they will have produced enough energy in noise to heat a cup of coffee.
Keith Edward
#106
Feb4-13, 06:53 PM
P: 2
http://personal.stevens.edu/~mmohdisa/about.html

Beyond this, there is now a capsule that generates microvoltage from low-frequency sound that powers implanted medical devices.

The tech is new. It will evolve. I envision a transfer process or interface that would further the efficiency of the process. If the SPL can be transferred to a more effective conductor (liquid) I could see it being harvested more expressly.

I keep watching with fascination.
sophiecentaur
#107
Feb5-13, 12:19 PM
Sci Advisor
PF Gold
sophiecentaur's Avatar
P: 11,873
Quote Quote by Keith Edward View Post
http://personal.stevens.edu/~mmohdisa/about.html

Beyond this, there is now a capsule that generates microvoltage from low-frequency sound that powers implanted medical devices.

The tech is new. It will evolve. I envision a transfer process or interface that would further the efficiency of the process. If the SPL can be transferred to a more effective conductor (liquid) I could see it being harvested more expressly.

I keep watching with fascination.
Did you read the conclusions? The Power levels involved are laughable (of course) in the results. Why would you expect that a "more effective conductor" would help? What new principle would it all be based on? They have used their resonators in an attempt to match the impedance of the incoming sound to their energy converter and they have a detectable amount (but so does any microphone) but they do not claim to be getting any more energy than is actually available.
Do you really believe that 'somewhere out there' there is a vast amount of acoustic power? If there were then we would be deafened!
sophiecentaur
#108
Feb6-13, 05:15 AM
Sci Advisor
PF Gold
sophiecentaur's Avatar
P: 11,873
Quote Quote by LastTimelord View Post
Noise is not a very large amount of energy at all. If a person were to scream as loud as they could for 5 years, they will have produced enough energy in noise to heat a cup of coffee.
If you go into some cafes, you would have to scream a lot longer than that before you were served?


Register to reply

Related Discussions
Electrical dark, and spectrum noise. General Physics 1
Converting mechanical to electrical energy Classical Physics 2
Converting energy Atomic, Solid State, Comp. Physics 2
Converting from sound to electrical energy? General Physics 1
Converting energy General Physics 14