Auditory sensation is one of the important sensation for human beings as it provides us the pleasure of enjoying sound. The physical stimulus for auditory sensation is sound waves.Auditory sensation is the experience of sound on ear. Ear is the receptor of auditory sensation .Frequency and intensity of sound determines the nature of sound.
Working of ear(Sensation in ear):
Our ears is divided into three parts:outer ear ,middle ear. And inner ear.The sound waves from the ear are first collected by the outer ear(pinna).It channels them into the auditory canal to reach and bump up against the eardrum,the thin stretchable ,vibrating membrane that separates the eardrum to vibrate. The quivering of the eardrum causes three tiny bones in the middle ear called the hammer(Malleus),the anvil(Incus)and the stirrup(stapes) to hit each other in sequence and carry the vibrations to the inner ear. The last of these three bones,the stirrup is loosely connected to the oval window. Just below the oval window ,there is a membrane called the round window which tries to equalize the pressure in the inner ear when the stirrup hits against the oval window.
The oval window is a membrane of the cochlea,the inner ear mechanism. The cochlea is a pea-sized coiled tube. It is filled with some fluid and contains the basilar membrane stretched throughout its lengths. Once transmitted across the oval window and into the inner ear , the sound waves set up a disturbance in the fluids contained in the cochlea. When the fluids in the cochlea begin to move , the basilar membrane vibrates. The basilar membrane then transmits the sound vibration to the actual auditory receptors-hair cells located on the organ of Corti,a structure that is attached to the basilar membrane. As waves travel through the cochlea ,the hair is moved and the hair cells are pulled by their movement. Stimulation of the hair cells , in turn , excites the spinal ganglion cells , which send neural impulses through the auditory nerve to the brain.