SAT VOCAB TWO Audible (adj.) able to be heard Oscillate (v.) to sway from one side to another Dissonance (n.) lack or harmony or consistency Undulate (v.) to move in waves

SAT VOCAB TWO Now that we are through with waves, we are moving onto the topic of sound. Sound waves are waves that are _______________. The reason we can hear them is that the waves make our ear drum ___________________ because the wave _______________ in the ear canal. When we hear something that is not of a pleasing quality, it creates ________________ and we think of it as noise.

Sound Chapter 12

REVIEW Waves transport ENERGY, not matter. Waves are mechanical (matter) or non-mechanical (no matter). Sound is mechanical. Light is non-mechanical. Transmission of Sound

SOUND WAVES Sound waves are Compressional waves. The vibrations of the molecules are parallel to the direction of the wave. Produced by the compressions and rarefactions of matter.

SOUND WAVES Sound is produced by a vibrating object. As one individual particle is disturbed, it transmits the disturbance to the next interconnected particle. This disturbance continues to be passed on to the next particle. The result is that energy is transported without the actual transport of matter.

SOUND WAVES LABEL YOUR DIAGRAM

SOUND WAVES

WHAT DO SOUND WAVES LOOK LIKE Visualizing Sound

SPEED OF SOUND Speed depends upon how fast one particle can transfer its motion to another particle. Speed of sound depends on the Elasticity Medium (Density) Temperature Why? Sonic boom

SPEED OF SOUND Speed of Sound: depends on the elasticity, density and temperature. Elasticity – the ability of an object to bounce back to its original shape. Sound travels faster in more elastic objects. Typically gases are the least elastic, liquids are next and solids are the most elastic. Density – generally speaking, in material of the same state of matter (solid, liquid or gas) the denser the medium the slower the sound travels. Sound travels slower in lead than it does in steel. Temperature – generally speaking the higher the temperature, the faster the speed of sound.

SPEED OF SOUND Speed of Sound – on average Air is 767 mph (346 m/s) – about 1 mile per 5s. Water is 3,315 mph (1,482 m/s) about 1 mile per 1.1s. Steel is 13,330 mph (5,960m/s) about 1 mile per 0.27s or 3.7mile per 1s.

SPEED OF SOUND

SPEED OF SOUND

BREAKING THE SOUND BARRIER Chuck Yeager – first man to fly faster than the speed of sound Andy Green – first man to drive a land vehicle faster than the speed of sound. October 14, 1947 – in X1 “Glamorous Glennis” October 15, 1997 – in SuperSonic Car “Thrust SSC” 763 MPH

HOW WE HEAR

HOW WE HEAR When a sound wave reaches the ear, a series of high and low pressure regions hit the eardrum. The arrival of a compression or high pressure region pushes the eardrum inward; the arrival of a low pressure region serves to “pull” the eardrum outward. The continuous arrival of high and low pressure regions sets the eardrum into motion.

HOW WE HEAR Auricle (Pinna-the ear flap) – used to focus the sound waves into the ear canal Ear Canal (Auditory Canal) – focuses the sound onto the ear drum. Ear Drum (Tympanic membrane) – Sound starts the ear drum vibrating.

HOW WE HEAR Ear Drum vibrates Three smallest bones vibrate, one after the next Hammer (Malleus) is touching the ear drum & vibrates first. Next is the Anvil (Incus). Last is the Stirrup (Stapes). Eustachian Tube: tube that connects the middle ear with the throat. This allows the pressure on both sides of the ear drum to equalize.

HOW WE HEAR The Stirrup vibrates the oval window of the cochlea. Cochlea is a long fluid filled tube, folded in half and thencoiled up like a snail shell. The entire inner surface is lined with cilia, little hairs. Once cilia are vibrated, the attached nerves are stimulated & send signal to the brain. Balance is achieved by the semicircular canals. Three canals in three different planes are able to determine the body’s position in space .

HOW WE HEAR Need to know these structures & their function: Outer Ear, Middle Ear, Inner Ear, Auricle, Ear canal, Ear drum, Hammer, Anvil, Stirrup, Oval Window, Cochlea, Auditory Nerve, Semicircular Canals, Eustachian Tube.

PROPERTIES OF SOUND Intensity – the amount of energy the wave carries; sound level is measured in decibels (dB); it influences how far away a sound can be heard.

PROPERTIES OF SOUND Loudness – how we perceive intensity. depends on the amplitude. Larger amplitude means more pressure. Remember: amplitude is a measure of the amount of energy in the wave.

PROPERTIES OF SOUND

PROPERTIES OF SOUND Frequency – the number of wavelengths that pass a particular point (vibrations) per second, Hz. Human Hearing – between 20 Hz – 20,000 Hz. Below 20 Hz is called infrasound. Above 20,000 Hz is called ultrasound. Pitch - determined by frequency; the highness or lowness of sound. high frequency yields high pitch sounds Low frequency yields low pitch

PROPERTIES OF SOUND Low Pitch High Pitch Low to High Frequency Pitch and Frequency Resonance – when the frequency of sound matches the natural frequency of an object.

TACOMA NARROWS BRIDGE COLLAPSE Nov. 7, 1940 Galloping Gertie On a day of rather high winds, Gertie took on a 30-hertz transverse vibration (like sending waves down a rope by moving the end up and down) with an amplitude of 1½ feet! It later took on a twisting motion of about 14 hertz and quickly tore itself in two.

PROPERTIES OF SOUND Sound waves can be reflected. A reverberation is perceived when the reflected sound wave reaches your ear in less than 0.1 second after the original sound wave. An echo takes longer.

PROPERTIES OF SOUND Doppler effect Variation in the perceived pitch of a sound due to a moving sound source. “bunches up” in front of the source Spreads out behind the source

PROPERTIES OF SOUND Doppler Effect

PROPERTIES OF SOUND A sonic boom is the sudden onset and release of pressure after the buildup by a sound shock wave. Sonic Boom

This picture shows a sonic boom created by the THRUST SSC team car as it broke the land speed record and broke the sound barrier on land.

MUSIC VS NOISE Music is sounds that are deliberately used in a repeated pattern. Noise has random patterns and pitches. Sound Applications

MUSIC VS NOISE Materials have their own natural frequencies. Examples: guitar strings, wine glass, other musical instruments Resonance is the ability of an object to vibrate by absorbing energy at its natural frequency. Wine glasses

USING SOUND Acoustics is the study of sound. Sound is studied so that concert halls, classrooms, theaters, etc. can be constructed to minimize destructive interference and diffuse reflection.

ECHOLOCATION The use of sound waves and echoes to determine where objects are in space. Bats send out sound waves using their mouth or nose.   When the sound hits an object, an echo comes back. They can tell the distance between themselves and the object .  They can identify an object by the sound of the echo.

ECHOLOCATION They can even tell the size, shape and texture of  a tiny insect from its echo.   Most bats use echolocation to navigate in the dark and find food. VIDEO

SONAR Sonar - Sound Navigation and Ranging Sonar uses sound waves to 'see' in the water It is helpful for exploring and mapping the ocean because sound waves travel farther in the water than do radar and light waves.

ULTRASOUND a device that uses high frequency sound waves to create an image of some part of the inside of the body, such as the stomach, liver, heart, tendons, muscles, joints and blood vessels.

BIOACOUSTICS Bioacoustics is a branch of science concerned with the production of sound and its effects on living systems. Animals that generate infrasound include elephants, whales, alligators, hippos, rhinos, giraffe, lions, tigers and several birds. Animals that generate ultrasound include dolphins, bats, many birds and insects.

CYMATICS from Greek meaning “wave”. Typically a surface is vibrated and regions of maximum and minimum displacement are made visible in a thin coating of particles, paste or liquid. Different patterns emerge as the surface vibrates. Cymatics