Transcript Sound Part II - How do instruments make sound

Sound Part II
How do instruments make sound?
Well we already
know that sound is a
vibration. We have learned what sound
looks like, and how sound changes
amplitude and pitch.
So, how do instruments make sound?
How do they change the pitch, and
amplitude of the sound that they create?
Brass
Winds
Percussion
Strings
There are four different types of instruments:
Although they all look and sound
different, they all have one thing in
common, they vibrate.
But where they are different is how they
vibrate and how the instrument
resonates the sound.
When an instrument resonates a sound,
the material it is made from vibrates a
certain way, producing a particular tone,
or pitch.
Different materials will resonate in
different ways. Such as brass and steel.
Although they are both metals, they
sound very different when they vibrate.
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The same is true for organic material
such as wood. Organic means it is
grown. Wood is a very popular material
to make instruments out of…
http://www.alliedlutherie.com/weekly5.htm
And you guessed it… different types of
wood resonate differently, thus making
different sounds.
http://www.fretnfiddle.com/pages/fretwork.htm
So if I make two guitars exactly the
same, but one made of mahogany and
the other cherry, they will have subtle
differences in the way they sound.
So what is making the vibration with in
the instrument itself? Well each
instrument family works in a different
way.
Let’s look at the percussion family first.
When we hit the top of the drum we
make the drum head vibrate, and it
creates a sound.
Dr. Dan Russell Acoustics Animations
This model shows us how the drum
head vibrates after you strike it with a
stick, or your hand.
Dr. Dan Russell Acoustics Animations
As the head moves up and down it
creates a deep sound. The sound
resonates along the wood barrel, and
the sound comes out the bottom.
Dr. Dan Russell Acoustics Animations
Some drums can change there pitch by
striking the head in different places. But
they are limited as to what sounds they
can produce.
The String Family
Hitting a drum with a stick makes a great
sound. However hitting a string
instrument will not give you the same
result.
Striking or hitting is only one way to
create a sound.
The string family uses a method of rubbing
or plucking to produce beautiful sounds.
Violins and Cellos are two instruments
that are played by rubbing a bow over
steel strings.
A guitar is not played with a bow, instead
we use a pick to pluck or strum the
strings.
www.phys.unsw.edu.au/music
Once the string is vibrating, the sound
resonates into the wooden base around
it. The sound bounces around the inside
and comes out of the hole in the center
of the instrument.
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Bridge
Note these two little pieces of wood.
They are called a bridge. They are
located at each end of the instrument.
www.phys.unsw.edu.au/music
Bridge
It is the job of the bridge to keep the
string off of the guitar base. This allows
the string to vibrate with out rubbing on
the instrument.
www.phys.unsw.edu.au/music
Bridge
With out the bridge the string would
vibrate for only an instant before the
friction would stop the vibration.
The string instruments can change their
pitch to any note you want to play,
simply by pushing down on a string on
the neck of the instrument.
When you push down on the string you
shorten its length, thus making the string
vibrate at a faster rate.
The faster the string vibrates the higher
the pitch. The slower the lower the
pitch.
So in other words, when you push down
on a string you shorten the length so it
vibrates faster, thus making the sound a
higher in pitch.
Winds and Brass
Reed instruments, like the
saxophone, or clarinet use a “reed” to
create the vibration.
www.phys.unsw.edu.au/music
The reed vibrates when the musician
blows through it.
You hit the percussion instruments, pluck,
strum, or bow string instruments; and you
blow through a reed to play a saxophone.
So how does a flute make noise?
Flutes use the air itself to vibrate.
Players
Lips
The air jet
alternates going in
and out of the bore.
Bore of
the flute
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When the musician blows into the
bore of the flute. It causes the air to
compress and vibrate, as it alternates
going in and out of the flute.
www.phys.unsw.edu.au/music
Open
Closed
Wind instruments change their pitch
by covering holes in the pipe. When
the holes are covered it shortens the
length of the pipe that the vibration
can resonate in.
www.phys.unsw.edu.au/music
Closed
The shorter the length of the pipe
used, the higher the pitch.
www.phys.unsw.edu.au/music
Look at the difference between the wave
lengths, of the two flutes. Which one has the
lower pitch?
Lower
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The longer the length of the pipe, the
lower the pitch.
Brass
No reads to blow, no strings to pluck, no
skins to hit, nothing but brass. Musicians
just don’t blow into a trumpet... They
Buzz!
A buzz of the lips that is. When the
musician buzzes his lips into the mouth
piece it creates the vibration. The vibration
then resonates throughout the instrument.
Brass instruments change their pitch
much the same way wind instruments do.
They change the distance the vibration
travels before it leaves the end.
Most brass instruments have a system of
valves that shorten or increase the path of
the sound on its way out.
Again the shorter the distance the higher
the pitch. The longer the lower!
Trombones use a slide that increases and
shortens the distance within the tubes.
When you put all the instruments
together it sounds something like this...
Its time to play...
Using these words tell how
each of the following
instruments produces its
vibration
Traditional Indonesian Drum
The alboka is a double hornpipe or clarinet
native to the Basque region of Northern Spain.
Two European pan flutes
Oh look... There is
the bow!
shofar is a ram's horn that is used as a musical instrument for
religious purposes. It is used on Judaism's high holy days of Rosh
Hashanah and Yom Kippur. The shofar originated in Israel for
Jewish callings.
The hammered dulcimer is a stringed musical instrument
with the strings stretched over a trapezoidal sounding board.
A Bell is usually an open-ended hollow drum which
resonates upon being struck. The striking implement can be
a tongue suspended within the bell, known as a clapper.
The Ghaychak or Ghijak is a roundbodied musical instrument with 3 or 4
metal strings and a short fretless neck
The bugle is one of the simplest brass instruments; it is
essentially a small natural horn with no valves. All pitch
control is done by varying the player's embouchure, since
the bugle has no other mechanism for controlling pitch
Steel Drum
originating in the twin
island state of
Trinidad & Tobago
located in the
Caribbean.
Criteria
Creativity
60%
Quality of
Sound 20%
Over and
Above
Exceeds
Standards
Meets
Standards
Below
Standards
Stradivarius
Reincarnate
Les Paul
Wept
+ ______pts
60 pts
Yamaha
couldn’t’ have
built it better
Rocks in a
coke bottle...
a timeless
tradition
+ 1-5
Extra Points
Perfect Pitch
+ ______pts
Quality of
Work 20%
Made by a
Grandmaster
Craftsman
+ ______pts
Manual
Optional 10%
What can I say,
perfection squared
+ ______pts
59-50 _____ pts
Eight notes
Finely Tuned
make an
20 pts
octave
19-15___ pts
Exquisite
Workmanship
20 pts
Letter perfect
10 pts
My Mom
and/or Dad
did it
And they did a
great job too!
Zero pts
49-1_____ pts
Slightly out of
tune
14-1____ pts
Wow, and it
sounds great
too!
Zero pts
Looks Great
19-15__ pts
The paint was
still wet
14-1____ pts
Dad did a great
job with the
band saw
Zero pts
Short and sweet
9 pts
Printed off of the
web or poorly
written
8-1 _____pts
Embossed
typeface, nice
touch Mom
Zero pts
Home Work: Go home and look at your
instrument, does it have what it needs to
have? Does it have a resonance chamber?
What vibrates? What amplifies the sound?
Can you change the pitch? Can you change
the tone? If you can’t...
SOUND PROJECT IS DUE
THURSDAY
DECEMBER
TH
17
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Teacher Lecture Notes
This is a straight forward introduction to sound. Follow up this
lesson with tuning forks. Allow students to explore with them after
they have been instructed how to use them. Ask the question: How
can you hear it best? (pointing the tines at your ear) How can you
hear it the longest? (Placing the base of the fork on your skull) Can
you hear through your elbow? (Place the base of the fork on the big
bone in your elbow, while with the connected arm, place a finger in
your ear.) Have fun!!! 
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