4. Activity: Humming a Tune
▰Procedures:
Place your fingers on your throat and
hum your favorite song for 1 minute.
Questions:
▰What did you observed?
▰What did you feel when you hum?
▰How do you think your vocal chords make a
sound? 4
5. “Sound is produced when
matter vibrates. These
vibrations travel outwards
from the source.
5
5
6. Sound consists of waves and
these waves travel as a
longitudinal wave.
7. LONGITUDINAL WAVE
▰Longitudinal Waves are waves that are usually created by
pulling and pushing the material or medium. Alternating
compressions and rarefactions are observed.
7
8. LONGITUDINAL WAVE
▰These compressions and rarefactions move along with the
direction of the pushing and pulling activity of a material. Thus, the
wave moves parallel to the motion of material or the particles of the
medium.
8
9. LONGITUDINAL WAVE
▰The distance from one compression to the next or between two
successive compressions in a longitudinal wave is called wavelength.
9
10. LONGITUDINAL WAVE
▰If you count the number of compressions passing by a certain point
in 1 second, you are able to determine the frequency of a longitudinal
wave.
▰The greater the frequency, the higher the pitch
10
11. TRANSVERSE WAVE
▰ The movement of particles is perpendicular to the direction of
wave travel. The compressions resemble the trough while the
rarefactions are the crest.
11
Examples of transverse
waves include: ocean waves
electromagnetic waves –
light waves, microwaves,
radio waves.
14. 14
▰Sound waves that travel in air come in contact
with our eardrums causing it to vibrate.
▰People hearing sounds while submerged in a
pool is evidence sound travels through a liquid.
▰People hearing sounds with their ear pressed
against a table is evidence sound travels through
a solid.
NOTE!
▰People unable to hear sounds in a vacuum is evidence
sound requires a medium like solids, liquids and most
gases to travel.
15. Where does the sound
travel fastest: solid,
liquid or gas?
15
20. 20
The hotter the medium the faster the sound travels
▰With more collisions per unit time, energy is transferred
more efficiently resulting in sound traveling quickly.
21. The hotter the medium the faster the sound travels
▰ Speed of sound is directly affected by the temperature of
the medium.
▰Heat, just like sound, is a form of kinetic energy. At higher
temperatures, particles have more energy (kinetic) and thus,
vibrate faster. And when particles vibrate faster, there will be
more collisions per unit time.
▰With more collisions per unit time, energy is transferred
more efficiently resulting in sound traveling quickly.
21
22. 22
▰Sound travels at about 331
𝑚
𝑠
in dry air at 0˚ C. The speed of sound
is dependent on temperature of the medium where an increase is
observed with an increase in temperature.
▰T is the temperature of air in Celsius degree and 0.6
𝑚/𝑠
𝐶
is a
constant factor of temperature. Let’s try it out at a room temperature
of 25˚Celsius.
29. REVERBERATION
▰The prolongation of the reflected
sound is known as reverberation.
▰Reverberation refers to the
multiple reflections or echoes in a
certain place.
▰A reverberation often occurs in a
small room with height, width, and
length dimensions of approximately
17 meters or less. 29
30. ECHO SOUNDING
▰Echo sounding is used to map the
ocean floor and to determine the depth
of the ocean or sea by
transmitting sound waves into water.
▰Bats listen to the echoes to figure
out where the object is, how big it is,
and its shape or detect distances.
30
32. REFRACTION
▰Refraction is described as the change in speed
of sound when it encounters a medium of
different density.
▰This change in speed of sound during
refraction is also manifested as sort of
”bending” of sound waves.
32
33. 33
▰Sound waves propagating through air are bent and
undergo refraction when the air temperature varies (the higher
the temperature, the greater the speed of sound).
