9th Class Science Sound Human Ear

        Human Ear

Human ear is one of the most important sense organ which enables human to hear the sound distinctly, also to recognize the sound. The human ear is divided into three parts outer ear, middle ear and inner ear.

The outer ear consist of the pinna and ear canal. It collects the sound from the surrounding and transmit it to the middle ear. The middle ear consist of eardrum and three interconnected bones called hammer, anvil and stirrup. These three bones amplifiy the sound several times and transmit it to the inner ear. The inner ear consists of a liquid filled coiled tube called the cochlea. It converts these sounds into electrical signals and then send to the brain via auditory nerve. The brain interprets the sound and reacts accordingly.  

        The vibrations or the pressure variations inside the inner ear are converted into electrical signals by the______.

(a) Cochlea

(b) Anvil

(c) Hammer

(d) Stirrup

(e) None of these

Answer: (a)

          Vibrations inside the ear are amplified by the three bones namely the ______ in the middle ear.

(a) Hammer, Anvil and Pinna

(b) Auditory bone. Anvil and Stirrup

(c) Hammer, Cochlea and Stirrup

(d) Hammer/Anvil and Stirrup

(e) None of these

Answer: (d)

• Disturbance created in the medium is called waves.
• Sound is a longitudinal waves,
• The distance between two consecutive crest or trough is called wavelength.
• The number of vibration per second is called frequency.
• The maximum upward or downward displacement about the mean positon is called amplitude.
• The reflection of sound after striking the surface after some time is called echo.
• The persistence of sound after repeated reflection is called reverberation of sound.
• Ultrasound can be used in medical science for ultrasonography and echocardiography.
• Ultrasound can be used to find the distance of underwater objects..