Resonance, Sound Resonance, Sound Intensity, & Sound Intensity, & Sound

QualityQuality

Forced Vibrations...Forced Vibrations... ……occur when we make an object produce a occur when we make an object produce a

sound.sound.

Ex.Ex.– Clapping your handsClapping your hands– Hitting a tuning forkHitting a tuning fork– Playing a musical instrumentPlaying a musical instrument

Natural Frequency...Natural Frequency...

……the frequency at which an object the frequency at which an object produces a sound. produces a sound.

The natural frequency of a body depends The natural frequency of a body depends on its on its elasticityelasticity , , shapeshape , & , & materialmaterial compositioncomposition. .

Resonance...Resonance... A type of energy transferA type of energy transfer

Occurs when the natural frequency of two or Occurs when the natural frequency of two or more objects match.more objects match.

High intensity waves can destroy the object that High intensity waves can destroy the object that is vibrating.is vibrating.

More energy put into a forced vibration More energy put into a forced vibration increases sound intensity!!!increases sound intensity!!!

Increased wave amplitudeIncreased wave amplitude

The The “intensity”“intensity” refers to the amount of refers to the amount of energy that moves through a sound wave. energy that moves through a sound wave.

Intensity = P / (4Intensity = P / (4ππrr²)²)

LoudnessLoudness the physiological sensation related to sound intensity. the physiological sensation related to sound intensity.

Intensity increases by 10x and volume 2x for every increase in 10 decibels.Intensity increases by 10x and volume 2x for every increase in 10 decibels.

Source of SoundSource of Sound Loudness Loudness (db)(db)

Threshold of HearingThreshold of Hearing 00

ConversationConversation 6060

Ear Damage BeginsEar Damage Begins 8585

Amplified MusicAmplified Music 110110

Jet Airplane at 30 metersJet Airplane at 30 meters 140140

Sound QualitySound Quality Timbre Timbre (tamber)(tamber) is the sound quality is the sound quality

produced by an object or instrument.produced by an object or instrument.

BeatsBeats - the periodic variation in loudness of - the periodic variation in loudness of two sounds played together.two sounds played together.

A result of alternating constructive & A result of alternating constructive & destructive interference.destructive interference.

Ex. Instruments that are out of tune w/ each otherEx. Instruments that are out of tune w/ each other

The The beat frequencybeat frequency is equal to the is equal to the difference in the frequency of the two difference in the frequency of the two sounds.sounds.