INTENSITY DETERMINES LOUDNESS 2 3 ALL WAVES CARRY

INTENSITY DETERMINES LOUDNESS (2. 3)

ALL WAVES CARRY ENERGY � The more energy a wave carries, the more intense it is and the louder it will sound to listeners. � Waves with a higher amplitude will have greater intensity or loudness

� Intensity- has the amount of energy a sound wave

� Decibel- intensity � The (d. B) the unit used to measure sound greater the amplitude, the more intensity a sound wave has and the louder the sound will be.

Question � How does a drummer vary the loudness of the sound coming from the drums?

Answer � The drummer varies the energy with which he hits the drum � Loudness is also affected by the distance between the source and the listener

SOUND WAVES TRAVEL IN ALL DIRECTIONS � As the waves travel farther away, the energy is spread over a greater area. The intensity is decreased � The sound waves with lower intensities are heard as quieter sounds � Intensity can also be decreased when energy is absorbed in a medium.

INTENSITY OF A SOUND CAN BE CONTROLLED � Over time and distance, a sound wave gets weaker and weaker until the sound becomes undetectable � The pitch, however, does not typically change as sound grows weaker � So, even as amplitude decreases, the frequency stays the same � Changing the intensity of a sound wave changes its amplitude

Question � How can sound intensity be controlled?

Answer � Mufflers noise on cars and trucks reduce engine � Have you heard a car without a muffler or with a broken muffler? � Some exhaust systems are designed to be louder than others

Question � How can you change the intensity of a sound without changing the pitch?

Answer ◦ Amplification � Amplification- the increasing of the strength of an electrical signal- It is often used to increase the intensity of a sound wave

� Acoustics-the scientific study of sound � It involves both how sound is produced and how it is received and heard by humans and animals � Acoustical engineers help design buildings to reduce unwanted echoes. They may add tiles that are designed to absorb or redirect the energy of sound waves.

INTENSE SOUND CAN DAMAGE HEARING � Continual exposure to sounds of 90 d. B or louder can damage or destroy the cells in your cochlea � Ear protection is used to help prevent damage to these cells �A typical rock concert is between 85 and 120 d. B � Noises above 130 d. B are dangerous and noises above 140 d. B can be painful

USES FOR SOUND � Intense sound frequencies are used in ultrasounds which can break up kidney stones or examine organs and fetuses. � Music, Telephones

� Echolocation-sending ultrasound waves and interpreting the returning sound echoes � Sonar- “sound navigation and ranging” � Dolphins and some whales use echolocation to locate objects underwater