Sound is a mechanical wave that requires a medium to travel. It is produced when an object vibrates, exerting a force on the surrounding air or medium. The loudness of a sound is measured in decibels, with louder sounds having higher amplitudes. Sound travels fastest through materials with high density, as the closer molecules can transfer energy more quickly through collisions. The human ear can detect sounds from 20-20,000 Hz but some animals can hear ultrasonic or infrasonic waves outside this range.

1. SOUND
KRIS ANN MAE YAP- BONILLA
GRADE 7 SCIENCE
SUBIC NATIONAL HIGH SCHOOL

2. Sound is a mechanical
wave (requires a medium
to travel) and a
compressional/ longitudinal
wave (molecules colliding).

4. Compressions
The close together part of the wave
Rarefactions
The spread-out parts of a wave

7. Waves transfer energy
without transferring matter.

9. In which media does sound
travel fastest?
 Sound travels better through high-density
materials
 The closer the molecules are together, the faster they
can collide and transfer energy

10. Hearing and the Human Ear

13. Properties of Sound

14. Pitch
-description of how high or low
the sound seems to a person
Loudness
how loud or soft a sound is
perceived to be.

15. Loudness of Sound in Decibels
Sound Loudness
(dbs)
Hearing
Damage
Average Home 40-50
Loud Music 90-100 After long
exposure
Rock Concert 115-120 Progressive
Jet Engine 120-170 Pain

16. KINDS OF SOUND WAVES
1. AUDIBLE SOUND
- human ear can hear
( 20 – 200 000 Hz)
2. ULTRASONIC WAVES
above 20 000 Hz
- Cannot be detected by human ear but some
animals do.
- Dogs can detect as high as 50 000 Hz and bats
can hear up to 100 000 Hz.
- Uses in ULTRASOUND

18. - Sound below 20 Hz.
SOURCES OF INFRASOUND:
- Vibrating heavy machines
- Earthquakes
- Thunder
- Volcanoes
- It cannot be heard by human ear but can cause
damage.
3. INFRASOUND WAVES

19. The range of hearing,
singing, and the quality of
notes.

24.  Sound is produced when an object
vibrates.
 When an object vibrates it exerts
a force on the surrounding air
 Loudness of a sound is recorded in
decibels
 As a sound gets louder, the
amplitude of the wave increases.

25.  The moving air mass carries the
sound of the vibration to your ear.
 The air is the MEDIA that it travels
through.
 Medium is what the wave travels
through (ex. solid, liquid, gas)
 NO MEDIUM NO SOUND!!!!

26. Self Check!