Sound 4th Grade Science

Sound Sound is produced when energy causes particles to vibrate. Sound carries energy. Sound travels in waves. These waves are different than light waves. These waves travel longitudinally.

Sound waves Sound waves move out in all directions from a vibrating object. You hear something when the vibrations strike your ear.

Longitudinal Waves Rarefaction Compression Section of a longitudinal wave where the particles are less crowded than normal Compression Section of a longitudinal wave where the particles are crowded together

How does sound travel? Sound must have a medium to travel. Sound cannot travel in a vacuum. Sound travels at different speeds. Sound travels in solids fastest and gases the slowest.

All sounds are not alike Wavelength dependent Frequency determines pitch. Measured in Hertz. (Hz) Amplitude determines loudness. Measured in Decibels.

How do we hear sound? Label on your worksheet- Write what is underlined 1. Outer Ear The outer ear collects sound waves. It acts like a funnel to direct sound waves into the ear. 2. Eardrum Sound waves make the eardrum vibrate like the head of a drum. 3. Middle Ear The vibrating eardrum makes three tiny bones in the middle ear vibrate. They are the hammer, anvil, and stirrup. 4. Inner Ear The little vibrating bones pass sound vibrations along to a tube that is filled with fluid in the inner ear. The fluid then vibrates. The vibrating fluid makes tiny hair cells vibrate, too. 5. Nerve to Brain The vibrations of the hair cells are passed along to a nerve that carries sound messages to the brain. The brain processes the messages, and you hear sound.

Frequency = Pitch Number of times a sound source vibrates in one second. Frequency determines pitch. Pitch is the highness or the lowness of a sound. A frog’s croak vs. a kitten's meow

Amplitude = Loudness The amount of energy in the sound wave Amplitude is related to loudness of a sound. Loudness is measured in decibels. Loud sounds can damage your hearing.

Echoes, sonar and echolocation Echoes occur when sound waves bounce off of a surface and they are heard again. Sonar is used with bouncing sound waves Bats use echolocation to find insects.

Tools and sound Stethoscopes Hearing aids Ultrasound

Sound quality - noise A pleasant sound has a regular wave pattern. The pattern is repeated over and over. But the waves of noise are irregular. They do not have a repeated pattern.

Sound- DRAW THE PICTURE AND LABEL!` Must have a vibration - motion starts sound energy Must have a medium – matter must transfer energy in a wave Must have a receiver – vibrations must reach an ear