2. Standards we will be covering
1. Waves can be transverse or longitudinal
2. Visual representation to construct an explanation of the
differences in transverse and longitudinal waves by
focusing on the vibration that generates the wave.
3. Relationship between wave speed, wavelength and
frequency
4. Standing waves - nodes, antinodes, reflections, boundary
conditions
3. Our Experiment
CJ being a violin player and Jesus being a guitar player, we decided to explore
why different instruments produce differing sounds even when playing the
same note
We discovered that we hear the same fundamental frequency as the pitch, but
the different instruments do not produce the same harmonics
4. Our Experiment (cont.)
We then wondered, why do the instruments create the same fundamental
frequency, but different harmonics?
There are many reasons to why this occurs:
Different bodies - A guitar body is much larger than that of a violin, and it is structured differently,
creating different vibrations
Instruments are constructed from different materials. Jesus’ electric guitar has strings made of
metal, whereas violins can have metal or nylon strings. Different materials create different
sound
The violin is played with a bow, which may impact the sound produced
5. How do stringed instruments work?
The vibrations of the strings on the instrument displace air molecules to create
sound
The vibrations of the strings alone are not enough, since the strings displace very
small amounts of space
However, when attached to a longer object, such as the body and neck of a
guitar, the strings displace more air
The strings cause the body of the instrument to begin vibrating at the same
frequency as the string, and the body of the instrument sends air molecules in
motion, creating sound
6. Understanding Waves on String Instruments
Standing waves are produced when a string is
plucked by the vibration reaching the end of
the string and reflecting back the other way
(we see this as the string moving up and
down or vibrating back and forth)
There is a place among the string where the
string is actually not moving, or the
displacement of the string is actually zero,
these are referred to as nodes
Inversely, there is a place on the string in which
the string has moved its maximum amount
producing the amplitude on the soundwave,
where the displacement of the string is
greatest, this is referred to as antinodes
7. Transverse Waves in music
A transverse wave is produced when when the oscillations of the wave form
right angles with the direction the wave is traveling, in other words the
vibration of the string is perpendicular to the direction it is traveling.
A longitudinal wave is produced when the oscillation of the wave are parallel to
the direction the wave is travelling; similar to a slinky type motion.
8. Transverse Waves in music (cont.)
When a string is played on an instrument, it displaces the air molecules around it
with vibrations
The vibrations caused by the string being plucked are caused by transverse
waves
Once the air molecules are vibrating to create sound, the sound waves, as all
sound waves, create longitudinal waves
9.
10. Wavelength, frequency, and pitch
Wavelength is how long a wave is
Longer waves oscillate slower, that is what causes the waves to be longer
The wavelength of a wave determines the frequency - the frequency of the
particles of air moving when a wave passes
Longer wavelength = Lower frequency
Shorter wavelength = Higher frequency
Frequency is measured in Hertz (Hz)
Pitches are measured in Hertz
