# 0.4 Jbs2000-what is sound?  (Page 2/3)

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## Sensing vibration

If you are standing somewhere between the car and the point at which the vibrations are no longer significant, the air molecules in your ear canals willbegin to vibrate. This will stimulate nerves that lead from your ear to your brain. Your brain will interpret the stimulation as something that we refer to sound .

Therefore, when the tree falls, it causes the air molecules to vibrate. However, if there are no ear canals around, no nerves to be stimulated, and no brain to interpretthat stimulation, there is no sound.

## Creating sound with a hammer

All we need to do to cause a person to experience sound is to cause the air molecules in that person's ear canals to vibrate at afrequency somewhere between 20 Hz (cycles per second) and 20,000 Hz, depending on the person's age. Usually as a person ages, the range defined bythose upper and lower limits decreases. Thus, a young person may "hear" the high-pitched whine of a power saw while an older person may not experience soundin that situation.

There are many ways that we can cause most humans to experience sound. One way for example, is to strike a bell with a hammer. Another way is to write aprogram to cause the diaphragm of a computer speaker to vibrate. That will be the topic of the next few modules in this course.

## Creating sound with a computer

One way to create sound with a computer would be to hold it out and drop it on the floor. However, that is not what we intend to do. Instead, we intend towrite computer program that will cause the computer to create sound.

## An object of a class

As you will learn in a future module, we can define a class and instantiate an object of that class for use in producing sound with a computer. When usedproperly in a program, that object will cause signed numeric values stored in an array to be converted to electrical current in the speakers attached to the computer.Positive values will cause the current to flow in one direction and negative values will cause the current to flow in the opposite direction.

## Alternating positive and negative values

If we populate that array with alternating groups of positive and negative values, that will cause the current being delivered to the speakers toalternate, switching from one direction to the other. The level of the alternating currents will be roughly proportional to the magnitudes of thealternating positive and negative values. Given sufficient magnitude within a frequency range supported by the speakers, the alternating currents will causethe diaphragms of the speakers to vibrate or move back and forth. This, in turn, will cause the adjacent air molecules to vibrate, which may be sensed as soundby a person within hearing distance of the speakers.

## Populating the array

There are many ways that we can write a program to populate the array with alternating groups of positive and negative numbers. One of the simplest ways is topopulate the array with scaled versions of the values produced by the static sin function or the static cos function of the Math class. The Math class is contained in the Java Standard Edition class library. A common name for a series of such values is sinusoid .

where we get a research paper on Nano chemistry....?
what are the products of Nano chemistry?
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
Preparation and Applications of Nanomaterial for Drug Delivery
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
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