THE MUSIC OF SOUND
Sound :
Sound is a form of energy which produces sensation of hearing in our ears.
Production of sound :
Sound is produce due ti vibrations of an object such as a stretched membrane or a string under tension.
Waves:
A wave is a disturbance movng through a medium when the particles of the medium set neighbouring particles in motion .A wave motion is a mode of transmission
of energy through the medium .A wave in ehich the particled of the medium oscillate (vibrate)about their mean positions in a direction perpendicular to the direction of wvae
propagation is called a transverse wave .
A wave in which the particles of the medium oscillate (vibrate ) about their mean posiotions in a direction parallel to the direction of wave propagation is called a longitudinal wave.
The particles do not move from one part to another part of the medium.
Propagation of sound :
Sound requires a medium for propagation .i.e. ,it cannot travel through vaccum. Sound propagetes in the fom of longitudinal waves.
As sound propagates through a medium,there is a change in the density and pressureof the medium.
Compressions are regions of highestpressure as well as highest density and rarefactions are regions of lowest pressure as well as lowest density.
Range of hearing in humans :
The range of hearing in humans is from 20 Hz to 20000 Hz.
Infrasound and ultrasound:
The sound of frequency less than 20 Hz. is called infrasound and that of frequency more than 20000 Hz. is called ultrasound.
We cannot hear infrasound and ultrasound.
Ultrasound are used 1) to establish ship to ship communication
2)for welding plastic surfaces
3) to kill bacteria in liquids like milk to preserve them
4)in echocardiography
5) for imaging internal organs of the human body
6) in industry to clean parts of a machine
7) to detect cracks and flaws in metal blocks.
Reflection of sound :
Sound waves follow the same laws of reflection as followed by light waves .
The directions in which sound is incident and reflected make equal angles with the normal to the reflecting surface at the point of incidence and the three are in the same plane.
Echo and reverberation:
Repetition of sound due to reflection of original sound from a surface is called echo.
The sensation of sound persists in our brainfor about 0.1 second.
The speed of sound in air at 22 degree Celsius is 344 m/s.
Hence ,for hearing distinct echo ,the minimum distance of the reflecting surface from the souce of sound must be 17.2 m in air at 22 degree Celsius .
The persistence of sound due to repeated reflection of ssound in a big hall or an auditorium is called reverberation.
SONAR:
Sound Navigation And Ranging (SONAR) refers to determination of the distance and location underwater objects using ultrsonic waves.
The human ear :
The human ear converts pressure variations in air with audible frequencies into electrical signals that travel to the brain ,via th eauditory nerve.Hence ,we can hear sound.
Frequency = 1/ time period
Speed of sound = frequency * wavelength
Sound :
Sound is a form of energy which produces sensation of hearing in our ears.
Production of sound :
Sound is produce due ti vibrations of an object such as a stretched membrane or a string under tension.
Waves:
A wave is a disturbance movng through a medium when the particles of the medium set neighbouring particles in motion .A wave motion is a mode of transmission
of energy through the medium .A wave in ehich the particled of the medium oscillate (vibrate)about their mean positions in a direction perpendicular to the direction of wvae
propagation is called a transverse wave .
A wave in which the particles of the medium oscillate (vibrate ) about their mean posiotions in a direction parallel to the direction of wave propagation is called a longitudinal wave.
The particles do not move from one part to another part of the medium.
Propagation of sound :
Sound requires a medium for propagation .i.e. ,it cannot travel through vaccum. Sound propagetes in the fom of longitudinal waves.
As sound propagates through a medium,there is a change in the density and pressureof the medium.
Compressions are regions of highestpressure as well as highest density and rarefactions are regions of lowest pressure as well as lowest density.
Range of hearing in humans :
The range of hearing in humans is from 20 Hz to 20000 Hz.
Infrasound and ultrasound:
The sound of frequency less than 20 Hz. is called infrasound and that of frequency more than 20000 Hz. is called ultrasound.
We cannot hear infrasound and ultrasound.
Ultrasound are used 1) to establish ship to ship communication
2)for welding plastic surfaces
3) to kill bacteria in liquids like milk to preserve them
4)in echocardiography
5) for imaging internal organs of the human body
6) in industry to clean parts of a machine
7) to detect cracks and flaws in metal blocks.
Reflection of sound :
Sound waves follow the same laws of reflection as followed by light waves .
The directions in which sound is incident and reflected make equal angles with the normal to the reflecting surface at the point of incidence and the three are in the same plane.
Echo and reverberation:
Repetition of sound due to reflection of original sound from a surface is called echo.
The sensation of sound persists in our brainfor about 0.1 second.
The speed of sound in air at 22 degree Celsius is 344 m/s.
Hence ,for hearing distinct echo ,the minimum distance of the reflecting surface from the souce of sound must be 17.2 m in air at 22 degree Celsius .
The persistence of sound due to repeated reflection of ssound in a big hall or an auditorium is called reverberation.
SONAR:
Sound Navigation And Ranging (SONAR) refers to determination of the distance and location underwater objects using ultrsonic waves.
The human ear :
The human ear converts pressure variations in air with audible frequencies into electrical signals that travel to the brain ,via th eauditory nerve.Hence ,we can hear sound.
Frequency = 1/ time period
Speed of sound = frequency * wavelength
