sound grade 7
TRANSCRIPT
SOUND
KRIS ANN MAE YAP- BONILLAGRADE 7 SCIENCESUBIC NATIONAL HIGH SCHOOL
Sound is a mechanical wave (requires a medium
to travel) and a compressional/ longitudinal wave (molecules colliding).
Compressions
The close together part of the wave
Rarefactions
The spread-out parts of a wave
Waves transfer energy without transferring matter.
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
Hearing and the Human Ear
Properties of Sound
Pitch- description of how high or low
the sound seems to a person
Loudnesshow loud or soft a sound is
perceived to be.
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
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
- 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
The range of hearing, singing, and the quality of
notes.
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.
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!!!!
Self Check!