SOUND

Sound waves whose frequencies are less than 20 Hz are in the infrasonic sound. e . g earthquakes, thunder, volcanoes , elephants and whales etc.

Musical sound is one which is pleasing to the ear. e g Sound produced by a harmonium is a musical sound. The string of a sitar also gives out a musical sound.

unpleasant sounds are called noise. e g Classroom

Some animals can hear sounds of frequencies higher than 20,000 Hz. that is called Ultrasonic sound wave .Dogs have this ability. The police use high frequency whistles which dogs can hear but humans cannot.The ultrasound equipment, familiar to us for investigating and tracking many medical problems, works at frequencies higher than 20,000 Hz.

Audible and Inaudible SoundsThe fact is that sounds of frequencies less than about 20 vibrations per second (20 Hz) cannot be detected by the human ear. Such sounds are called inaudible. On the higher side, sounds of frequencies higher than about 20,000 vibrations per second (20 kHz) are also not audible tothe human ear. Thus, …

What are an Audible and Inaudible Sounds? Read More »

The frequency determines the shrillness or pitch of a sound. If the frequency of vibration is higher we say that the sound is shrill and has a higherpitch. If the frequency of vibration is lower, we say that the sound has a lower pitch.

Loudness of sound is proportional to the square of the amplitude of the vibration producing the sound. For example, if the amplitude becomes twice, the loudness increases by a factor of 4. The loudness is expressed in a unit called decibel (dB). The following table gives some idea of theloudness of sound coming from various …

Loudness of sound Read More »

The to and fro motion of an object is known as vibration. This motion is also called oscillatory motion.

 It is the height of crest or depth of trough from the mean position of the wave. S I unit of amplitude is meter ( m) . C G S unit of amplitude is cm

The number of oscillations per second is called the frequency of oscillation. Frequency is expressed in hertz. Its symbol is Hz. A frequency of 1 Hz is one oscillation per second.