SOUND WAVES, HEARING AND INTERACTIONS

A sound wave is a longitudinal, mechanical wave that is caused by vibrations and travels through a medium. SOLID - fastest LIQUID – slower than solid GAS – slowest

LONGITUDINAL WAVES ARE ALSO CALLED COMPRESSION WAVES LONGITUDINAL WAVES ARE ALSO CALLED COMPRESSION WAVES. ------------------- - - - - - - - - ----------------- COMPRESSION RAREFACTION COMPRESSION

SOUND WAVES NEED A MEDIUM…… A MEDIUM REFERS TO THE MATERIAL, MADE UP OF MOLECULES TO TRAVEL THROUGH…..NO MEDIUM, NO SOUND. THERE IS NO SOUND IN SPACE.

OUR EARS CONVERT MECHANICAL SOUND WAVE VIBRATIONS TO ELECTRICAL SIGNALS. THESE ELECTRICAL SIGNALS ARE SENT TO THE BRAIN TO ALLOW US TO INTERPRET SOUNDS.

PITCH! LOW PITCH = LOW FREQUENCY HIGH PITCH = HIGH FREQUENCY

FREQUENCY IS EXPRESSED IN HERTZ (Hz). 1 HERTZ = 1 WAVE LENGTH.

THE HIGHER THE FREQUENCY – THE SHORTER THE WAVE LENGTH – THE HIGHER THE PITCH!

THE LOWER THE FREQUENCY – THE LONGER THE WAVE LENGTH – THE LOWER THE PITCH!

A SOUND’S LOUDNESS IS ITS WAVE HEIGHT OR AMPLITUDE A SOUND’S LOUDNESS IS ITS WAVE HEIGHT OR AMPLITUDE. AMPLITUDE IS MEASURED IN UNITS CALLED DECIBELS (Db).

THE DOPPLER EFFECT IS A CHANGE IN THE OBSERVED FREQUENCY (PITCH) OF A SOUND WAVE WHEN THE SOURCE, THE OBSERVER, OR BOTH ARE MOVING. MOVING TRAIN & CAR HORN SOUNDS ARE BEST.

BEFORE THE SOURCE = HIGH PITCH. AFTER THE SOURCE = LOW PITCH.

ECHO !-------------------------ECHOOO!

A REFLECTED SOUND IS AN ECHO. THE MORE REFLECTED THE BETTER THE ECHO.

BATS, DOLPHINS & WHALES USE ECHOLOCATION TO FIND FOOD AND EACH OTHER.

SONAR IS A TYPE OF ECHOLOCATION ORIGINALLY USED BY THE NAVY – NOW WE USE TO FIND FISH.