WHAT IS SOUND?• Sound is – A form of energy made by vibrations. – When an object vibrates it causes the air particles around it to move. – These particles bump into particles close to them and this continues until they run out of energy.
TRY THIS:• Put your finger on your neck and say “aah” as loud as you can.• Now say it as soft as you can.• You can not only hear the sound, but you can feel the vibration inside your throat.
HOW SOUND TRAVELS?• Sound passes through the medium as longitudinal waves.• When the vibrations are fast you hear a high pitch. When they’re slow, you hear a low pitch. High Pitch Low Pitch
PRODUCTION OF SOUND Sound is produced due to the vibration of objects. Vibration is the rapid to and fro motion of an object.Eg :- The sound of human voice is produced due to the vibration of the vocal cords. A stretched rubber band when plucked vibrates and produces sound.Activity :- Strike the prongs of a tuningfork on a rubber pad and bring it nearthe ear. We can hear a sound. If a Threadsuspended table tennis ball is touched Table tennis ballwith the vibrating prong, the ball ispushed away repeatedly. This shows Vibratingthat the prong is vibrating and tuning forkvibrating objects produces sound.
LOW SOUND AND HIGH SOUNDThe pitch of sound (shrillness or flatness) depends on thefrequency of vibration. If the frequency is high, the sound has high pitch and ifthe frequency is low, the sound has low pitch.
• High pitch = high frequency• Low pitch = low frequency
SOUND NEEDS MEDIUM TO TRAVEL Sound is a mechanical wave and needs a medium for propagation. Sound travels through solids, liquids and gases. Sound does not travel in vacuum.Activity:- Suspend an electric bell in an air tight bell jar. Connect the bell jar to a vacuum pump. If the switch is pressed, we can hear the sound of the bell. If air is pumped out through the vacuum pump, we cannot hear the sound of the bell. This shows that sound needs a medium to travel and sound cannot travel in vacuum. Cork Bell jar Electric bell
AMPLITUDE OF SOUND• Volume control• Loudness• Strength of the wave ( measured in db “decibels”)• Energy of the wave
DO YOU KNOW HOW DOES MUSICAL INSTRUMENT CREATE SOUND• It depends on the type of instrument. There are four types. – Woodwind – String – Percussion – Brass
WOODWIN INSTRUMENTS• Woodwinds make music by blowing on the top of the instrument or on a reed. Clarinet Oboe Bassoon Flute Piccolo
STRING INSTRUMENTS • Strings make music by plucking or strumming the strings. Cello Guitar HarpViolin Electric Guitar
PERCUSSION INSTRUMENTS• Percussion instruments make music by striking, shaking or scraping them. Tambourine PianoDrum Xylophone Maracas Cymbals
BRASS INSTRUMENT• Brass instruments make music by buzzing lips while blowing. TromboneFrench Horn Tuba Trumpet
HOW DOES VIOLIN PRODUSES SOUND?The body of the violin is a large hollow chamber thatfunctions as a speaker or amplifier for vibration. Thestrings are suspended above the body of the instrument bya bridge, a small maple piece of wood secured to the topof the instrument by the tension of the strings. Thevibration from the strings is transferred through the bridgeto the body of the instrument where the sound is thenamplified.
HOW DOLPHINS COMMUNICATE EACH OTHEROne way they do it is by making sounds. They don’t have vocal chords like wedo, but they can control muscles in their blowholes to make different noises.Some of the noises they make sound like whistles and squeaks. Some of theirsounds are ultrasonic, which means they are too high in pitch for people toeven hear!By making all these sounds, dolphins can identify themselves to each other.
Whales sing to each other.Sound travelsthrough water
NOISE POLLUTIONSound that is unwanted or disrupts one’s quality of life is called as noise. When there is lot of noise in the environment, it is termed as noise pollution.Sound becomes undesirable when it disturbs the normal activities such as working, sleeping, and during conversations.It is an underrated environmental problem because of the fact that we can’t see, smell, or taste it.World Health Organization stated that “Noise must be recognized as a major threat to human well-being”
HEALTH EFFECTS• According to the USEPA, there are direct links between noise and health. Also, noise pollution adversely affects the lives of millions of people.• Noise pollution can damage physiological and psychological health.• High blood pressure, stress related illness, sleep disruption, hearing loss, and productivity loss are the problems related to noise pollution.• It can also cause memory loss, severe depression, and panic attacks.
SOURCES OF NOISE POLLUTION• Transportation systems are the main source of noise pollution in urban areas.• Construction of buildings, highways, and streets cause a lot of noise, due to the usage of air compressors, bulldozers, loaders, dump trucks, and pavement breakers.• Industrial noise also adds to the already unfavorable state of noise pollution.• Loud speakers, plumbing, boilers, generators, air conditioners, fans, and vacuum cleaners add to the existing noise pollution.
SOLUTION FOR NOISE POLLUTION• Planting bushes and trees in and around sound generating sources is an effective solution for noise pollution.• Regular servicing and tuning of automobiles can effectively reduce the noise pollution.• Buildings can be designed with suitable noise absorbing material for the walls, windows, and ceilings.• Workers should be provided with equipments such as ear plugs and earmuffs for hearing protection.
• Similar to automobiles, lubrication of the machinery and servicing should be done to minimize noise generation.• Soundproof doors and windows can be installed to block unwanted noise from outside.• Regulations should be imposed to restrict the usage of play loudspeakers in crowded areas and public places.• Factories and industries should be located far from the residential areas.
• Community development or urban management should be done with long- term planning, along with an aim to reduce noise pollution.• Social awareness programs should be taken up to educate the public about the causes and effects of noise pollution.
HUMAN VOICE BOX In humans sound is produced by the voice box or the larynx. The voice box is at the upper part end of the windpipe.Tow vocal cords, are stretched across the voice box or larynx in such a way that it leaves a narrow slit between them for the passage of air
Sound travels to your ear SoundThe air vibratesbut does not travel fromthe alarm to the ear.
HUMAN EAR The outer ear called pinna collects the soundwaves. The sound waves passes through the earcanal to a thin membrane called eardrum. Theeardrum vibrates. The vibrations are amplified bythe three bones of the middle ear called hammer,anvil and stirrup. The middle ear then transmitsthe sound waves to the inner ear. In the inner earthe sound waves are converted into electricalsignals by the cochlea and sent to the brainthrough the auditory nerves. The brain theninterprets the signals as sound.
Mobile phones use radio Sound - electrical signal - radio signal - electrical signal - soundIn one phone the In the second sound is changed phone the radio into an electrical signal is changed signal then into Mobile into an electrical a radio signal. phone signal then into sound. beacons Radio signalSound - electrical signal - radio signal - electrical signal - sound
TELEPHONES The message travels through miles of wires as an electrical signal. loudspeakermicrophone electrical signal
SOME INTRUSTING FACTSSound travels 4 times faster through water thanthrough air.There is no sound in space.Geologists use their knowledge of how soundtravels through rocks to help them find oil fields.Whales in the ocean "sing" to each other. Thesound of their song can travel a distance of800km.Sound moves through the air at 340m persecond.