reveals the science of guitar

2. Whether you're a musician or you simply enjoy listening
to music,
have you ever stopped to think about how a guitar
works?
What are frets for? What does the big hole in the front
do?
In this presentation, we'll explore exactly how guitars
make music!

3. Guitar Parts
A guitar can be divided into three main parts:
The hollow body
The neck, which holds the frets
The head, which contains the tuning pegs

4. The most important piece of the body is the soundboard.
This is the wooden piece mounted on the front of the guitar's body,
and its job is to make the guitar's sound loud enough for us to hear.
In the soundboard is a large hole called the sound hole.
The hole is normally round and centered,
but F-shaped pairs of holes, as in a violin, are sometimes seen.
Attached to the soundboard is a piece called the bridge,
which acts as the anchor for one end of the six strings.
The bridge has a thin, hard piece embedded in it called the saddle,
which is the part that the strings rest against.
When the strings vibrate, the vibrations travel through
the saddle to the bridge to the soundboard.
The entire soundboard is now vibrating.
The body of the guitar forms a hollow sound box that
amplifies the vibrations of the soundboard. If you touch a
tuning fork to the bridge of a guitar you can prove that
the vibrations of the soundboard are what
produce the sound in an acoustic guitar.

5. Sound, Tones, and Notes
The guitar is a musical instrument, so its goal in life is to make music.
Music is the arrangement of tones into patterns that the human brain finds
pleasing (or if not pleasing, then at least intriguing).
In order to better understand music,
let's start at the beginning: "What is sound?"
Sound is any change in air pressure that our ears are able to
detect and process.
For our ears to detect it, a change in pressure has to be strong enough
to move the eardrums in our ears. The more strongly the pressure changes,
the "louder" we perceive the sound to be.
For our ears to be able to perceive a sound,
the sound has to occur in a certain frequency range. For most people,
the range of perceivable sounds falls between 20 Hertz
(Hz, oscillations per second) and 15,000 Hz. We cannot hear sounds
below 20 Hertz or above 15,000 Hertz.
A tone is a sound that repeats at a certain specific frequency.

6. This 440-Hz tone can be pictured as a sine wave, like this:
A tone is made up of one frequency or a very small number of related frequencie
The alternative to a tone is a combination of hundreds or thousands of
random frequencies. We refer to these random-combination sounds as noise.
When you hear the sound of a river, or the sound of wind rustling through leave
or the sound of paper tearing or the sound made when you tune your TV
to a nonexistent station, you are hearing noise.

7. You can see in this diagram that there are 72 fret positions,
but the table above shows only 37 unique notes.
Therefore you have multiple ways to finger identical notes on
This fact is frequently used to get all of a guitar's strings tun
For example, you can tune A on the first string (5th fret) to 4
Then you know that E at the 5th fret on the second string
is the same as the open first string, so you match those two
notes up by tuning the second string. Similarly
:The 4th fret on the 3rd string (B) is the same as
the B on the open 2nd string. The 5th fret on the 4th string (
is the same as the G on the open 3rd string.
The 5th fret on the 5th string (D) is the same
as the D on the open 4th string. The 5th fret on the
6th string (A) is the same as the A on the open 5th string.
Once you have all of the strings on a guitar perfectly tuned,
using 440 Hz for A as the primary note,
then the guitar will have notes with the frequencies
shown in the table above,
and it is said to be tuned to "concert pitch."

8. Strings and Frets
How does a guitar generate the frequencies shown above?
A guitar uses vibrating strings to generate tones.
Any string under tension will vibrate at a specific frequency that is controlled b
The length of the string
The amount of tension on the string
The weight of the string
The "springiness" of the string's material.
On a guitar, you can see that the different strings have different weights.
The first string is like a thread, and the sixth string is wound
so that it is much thicker and heavier.
The tension on the strings is controlled by the tuning pegs.
The length of the open strings, also known as the scale length,
is the distance from the nut to the saddle.
On most guitars, the scale length ranges from 24 inches to 26 inches.
When you press down on a string at a fret you change the length of the string,
and therefore its frequency when vibrating.

9. The frets are spaced out so that the proper frequencies are produced
when the string is held down at each fret.
The magic number to use in positioning frets is 17.817.

10. The Guitar’s Sound
An acoustic guitar generates its sound in the following way:
When the strings on a guitar vibrate, they transmit their vibrations to the saddl
The saddle transmits its vibrations to the soundboard.
The soundboard and body amplify the sound.
The sound comes out through the sound hole.
The particular shape and material of the sound board,
along with the shape of the body and the fact that a guitar uses
strings, give a guitar its distinctive "sound."

11. One modification that a guitar makes to that tone is to add harmonics to it.
For example, when you pluck one string it plays the pure note,
but the string also rings at harmonics like two-times,
three-times and four-times the pure tone.
Other strings also pick up the vibrations from the saddle and
add their own vibrations as well.
Therefore, the sound you hear from a guitar for any given note
is actually a blend of many related frequencies.
To get an idea of the effect this sort of blending has.
Here is a 440-Hz tone with an 880-Hz tone (at half the amplitude) added to it:

12. A guitar also adds an envelope to any note it plays.
The note doesn't just start and stop abruptly -- it builds and trails off.
Over the course of the note, the amplitude (loudness) of the note changes.
For example, a guitar's envelope might look like this:

13. Made By
Dipin Sawlani
Roll No. C-19