sound grade 7

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!