Vibrations Sound waves are compression waves. They are made of atoms being pushed, or compressed, by other atoms. Why wouldn’t sound waves carry in space?

Sound waves are mechanical waves, which means they need a medium to travel through and they can’t travel through a vacuum.

Vibrations Parts of sound waves … Wavelength – distance between troughs on either side of a single wave.

Vibrations Parts of sound waves … Amplitude – height of the sound wave. high wave = loud low wave = soft

Vibrations Parts of sound waves … Frequency – speed, the number of vibrations per second. frequency = pitch fast vibrations = high pitch slower vibrations = low pitch

Vibrations Slowly through gases, more quickly through liquids, States of Matter Sound waves travel … Slowly through gases, more quickly through liquids, and fastest through solids

Vibrations

Vibrations Speed of Sound: 343 m/sec (Speed of Light: 300,000 km/sec) Which is faster?

Sound Question: Can you experience sound waves by feeling vibrations? When the bass is turned up high.

Sound Loudness is the human perception of how much energy a sound wave carries.

Sound Pitch: how high or low a sound is. Pitch corresponds to frequency. The higher the pitch the higher the frequency. Question: Name a musical instrument with a high pitch. Question: Name a musical instrument with a low pitch.

Sound Decibel Scale: measure of the energy carried by sound waves.

Sound Pitch: Humans can detect frequencies between about 20Hz and 20,000Hz. Dogs can detect up to 50,000Hz. Bats as high as 150,000Hz.

Sound Dangerous levels of sound energy. You must learn to protect your hearing or you may have hearing problems later in life. Have you ever had ringing in your ears?

Sound Echo: a reflected sound wave

Sound What is SONAR? Sound Navigation And Ranging. Uses sound to detect objects under the surface of the water. Videos: Submarines and Sonar 2, Dolphins Sonar 1:30

Sound Echolocation: emitting high pitched squeaks and listening for echoes to determine location. Bats and dolphins use echolocation to navigate. Video: Echoes and Echolocation 1:29

Sound Doppler Effect: The change in frequency that occurs when a source of sound is moving relative to the listener. Example the pitch of a siren gets higher as it moves toward you. As the siren moves away, the pitch gets lower. Radar guns use the Doppler effect. Video: Doppler Effect 1:28

Sound Sound waves can be used to treat certain medical problems. Small incision is made in the eye, then an ultrasonic instrument uses sound waves to break up the lens, and the particles are removed. Breaking up kidney stones. Video: Ultrasound 2:44

Music Natural frequencies: every object will vibrate at a certain frequency.

Music Music: a group of sounds deliberately produced to make a regular pattern. The difference between music and noise can vary from person to person. Music is created by vibrations. You beat a drum, the head vibrates. You play a guitar the string vibrates. You tap a bell, it vibrates at a certain frequency.

Music Most musical instruments produce more than one frequency at which they vibrate. Fundamental frequency: the lowest frequency produced by a vibrating object. Overtones: higher frequencies produced by a vibrating object.

Music Resonance: an object is made to vibrate at its natural frequency by absorbing energy from a sound wave. The vibrating tuning fork causes the table to vibrate at the same frequency, or resonate. The combined vibrations of the table and tuning fork increase the loudness of the sound waves produced.

Music Reverberation: repeated echoes of sound. In a empty gym the sound of your voice can be reflected back and forth several times by the floor, walls, and ceiling. Video: Reverberation 2:15

Ear

Definitions: anvil - (also called the incus) a tiny bone that passes vibrations from the hammer to the stirrup. cochlea - a spiral-shaped, fluid-filled inner ear structure; it is lined with cilia (tiny hairs) that move when vibrated and cause a nerve impulse to form. eardrum - (also called the tympanic membrane) a thin membrane that vibrates when sound waves reach it. Eustachian tube - a tube that connects the middle ear to the back of the nose; it equalizes the pressure between the middle ear and the air outside. When you "pop" your ears as you change altitude (going up a mountain or in an airplane), you are equalizing the air pressure in your middle ear. hammer - (also called the malleus) a tiny bone that passes vibrations from the eardrum to the anvil. nerves - these carry electro-chemical signals from the inner ear (the cochlea) to the brain. outer ear canal - the tube through which sound travels to the eardrum. pinna - (also called the auricle) the visible part of the outer ear. It collects sound and directs it into the outer ear canal semicircular canals - three loops of fluid-filled tubes that are attached to the cochlea in the inner ear. They help us maintain our sense of balance. stirrup - (also called the stapes) a tiny, U-shaped bone that passes vibrations from the stirrup to the cochlea. This is the smallest bone in the human body (it is 0.25 to 0.33 cm long).

Ear Outer Ear: Collects sound waves and directs them into the ear canal. (also called the pinna)

Ear Middle Ear: Sound waves vibrate the eardrum, which is a membrane that stretches across the ear canal. When the eardrum vibrates, it transmits vibrations to three small bones (hammer, anvil, stirrup) which amplify the sound

Ear Inner Ear: One of the three small bones vibrates another membrane leading into the inner ear, which is filled with fluid. Vibrations in the fluid are transmitted to hair-tipped cells. These cells generate signals containing information about sounds. The nerve impulses from the cells then travel to the brain. Video: Ear 1