Test: Sound - 2 - UPSC

The sound of single frequency is called tone. A number of tones together form a note of the sound.

Human ear consist of three parts- outer ear, middle ear and inner ear. The shape of outer ear is like a funnel through which vibration reaches to eardrum.

The speed of sound depends upon the material medium in which sound is travelling. Sound travels faster in solid (metals) followed by water and air respectively.

Vocal cords are situated in neck of human beings. Sound is produced due to vibration of vocal cords.

The number of vibration per second is called frequency. The pitch of sound depends upon frequency of sound.

The time takes to complete one vibration is called time-period. Time period is inversely proportional to frequency. Time-period 1/frequency

Tympanic membrane is another name of eardrum. When vibrations of audible range reach to eardrum it starts vibrating to produce sound.

drum vibrates to produce sound which is interpreted by brain.

Sound wave is longitudinal wave as it consists of compression and rarefaction. The region of high density form compression and that of less density rarefaction.

Ultrasound equipment is used for investigating and tracking medical problems. The sound of frequency greater than 20000 Hz is called ultrasound.

The SI unit of frequency is

The speed of sound in air is about 344 m/s and minimum time-interval between two sounds require is 0.1second to hear two sound. So, 2xdistance = speed x time = 344x0.1= 34.4 m. minimum distance from sound to reflecting surface is 17.2m.

The speed of sound increase with increase in temperature. At higher temperature, the particles of medium have higher energy to vibrate faster.

The motion of object which repeats after fixed interval of sound is called periodic motion. Simple pendulum is most common well-known periodic motion.

Sound cannot travel through vacuum as sound require material medium for its propagation. Sound can travel through air, water and solids.

The range of audible sound is 20Hz to 20,000Hz. The sound above the 20,000Hz is called ultrasound and less than 20Hz is called infrasound.

The sound of frequency more than 20,000Hz is called ultrasound. Ultrasound cannot be heard by human.

Ultrasound is used in echocardiography to known the functioning of heart. Echocardiography is common known as ECG.