Tilak college of education Technology based teching Roll no-92 Name : Rachna Kandalkar

SOUND

INRODUCTON As we are aware about sound it requires a medium for propagation The sound which is produced by the mechanical disturbances The sound waves are basically longitudinal waves in which particles do not moves one place to another but they oscillaated backe and up The frequency of sound is no of oscillations per unit time. The frequency of sound is represented by υ The SI unit is Hertz The speed of sound is v= λ. υ

Aim : To enable student to know about ultrasound and reflection of sound Many times we observe bats flying at night or dark without colliding any obstacle because they can hear and produce a sound of frequency higher than 20000Hz which human being cannot hear. This is known as Ultra sound. The sound which has frequency less than 20Hz called infrasound or infrasonic sound As an example sound produced by vibration of oscillation of pendulum and sound of earthquake by vibration of sound earth surface.

AUDIBLE RANGE OF HUMAN EAR…. Range of human being ear is from approximately 20Hz to 20000Hz. Under the age of five children can hear,dogs can hear up to 25000Hz As people grow older their ears becomes less sensible to higher frequency

Ultrasound Often we observe a dog raising its ears suddenly and becomes alert when stranger is approaching by a long distance. We cant see or hear the stranger but the dog can sense someone is coming so the sound waves having frequency greater than 20000Hz called ultrasound Dolphins, bats and rats can produce in nature The ultras sound has a special property that they can travel along the path even in presence of obstacles

Uses of ultrasound. Ultrasound is used to established ship to ship communication It is used for welding and plastic surfaces For industrial purposes They are well being used to kill bacteria in liquids like Preservation of milk The echocardiotechnique is based on ultrasound which is one of the great use among above.

REFLECTION OF SOUND DEFINITION The reflection of sound is the change in the direction of a wavelength at an interface between two different media so that wave front returns into medium from which is originated.

It is similar to light waves The sound waves gets reflected at surface of solids liquids It requires obstacle of large sized and rough.

SOUND PULLUTION Sound Pollution can Couse hypertension, high stress levels, tinnitus, hearing loss, sleep disturbances and other harmful effect. Sound becomes unwanted when it either interferes with normal activities such as sleeping, conversation, or disrupts or diminisher one’s quality of life.

SOUND CANTROL

SOUND LEVEL METER

Recapitulation What is the range of human being ear ? What is infrasound ? What is ultrasound ? What is sound pollution ?

Application

Assignment List the sound pollution sources and find out that controlling point

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