auditory

• The Hearing Sense The properties of sound are indeed similar to those of light, as both senses rely on waves. But the physical properties of sounds are different from those in light.
• The outer ear or pinna is the visible and external part of the ear that serves as a kind of concentrator, funneling the sound waves from the outside into the structure of the ear.
• Auditory canal or ear canal entrance to the pinna. The short tunnel that runs down to the tympanic membrane, or eardrum. When sound waves hit the eardrum, they cause three tiny bones in the middle ear to vibrate.
• The three tiny bones in the middle ear are known as the hammer(malleus), anvil (incus), and stirrup (stapes), each name stemming from the shape of the shape of the respective bone. The vibration of these three bones amplifies the vibrations from the eardrum. The stirrup, the last bone in the chain, causes a membrane covering the opening of the inner ear to vibrate.
• inner ear this membrane is called the oval window, and its vibrations set off another chain reaction within the inner ear.
• COCHLEA the snail-shaped structure which filled with fluid.
• basilar membrane is the resting place of the organ of corti which contains the receptor cells for the sense of hearing.
• On the organ of corti are special cells called hair cells, which are the receptors for sound
• hen these auditory receptors or hair cells are bent up against the other membrane, it causes them to send a neural message through AUDITORY NERVE
• AUDITORY NERVE (which contains the axons of all the receptor neurons) and into the brain, where the auditory cortex will interpret the sounds (the transformatrion of the vibrations of sound into neural messages is transduction).
• The louder the sound in the outside world, the stronger the vibrations that stimulate more of those hair cells – which the brain interprets as loudness.
• PITCH refers to how high or low a sound. Psychological experience of sound that corresponds to the frequency of the sound waves; higher frequencies perceived as higher pitches.
• PLACE THEORY based on an idea proposed by Hermann von Helmholtz, in this theory, the pitch of a person hears depends on where the hair cells are stimulated are located on the organ of corti.
• FREQUENCY THEORY developed by Ernest Rutherford in 1886, states that pitch is related to how fast the basilar membrane vibrates. The faster this membrane vibrates, the higher the pitch; the slower it vibrates, the lower the pitch.
• CONDUCTION HEARING IMPAIRMENT means that sound vibrations cannot be passed from the eardrum to the cochlea. The cause might be a damaged eardrum or damage to the bones of the middle ear (usually from an infection). In this kind of impairment, hearing aids may be of some use of restoring hearing.
• NERVE HEARING IMPAIRMENT the problem lies either in the inner ear or in the auditory pathways and cortical areas of the brain. Normal aging causes loss of hair cells in the cochlea, and exposure to loud noises can damage hair cells.
• Hearing or audition (audioception) is the sense of sound perception. Mechanoreceptors in the inner ear turn vibration motion into electrical nerve pulses. The vibrations are mechanically conducted from the eardrum through a series of tiny bones to hair-like fibers in the inner ear that detect the mechanical motion of the fibers.
• Sound can also be detected as vibrations conducted through the body by tactition. The inability to hear is called deafness or hearing impairment.
• Humans are able to hear a wide variety of sound frequencies, from approximately 20 to 20,000 Hz
• Our ability to judge or estimate where a sound originates, called sound localization, is dependent on the hearing ability of each ear and the exact quality of the sound.
• Bushy neurons can resolve time differences as small as ten milliseconds, or approximately the time it takes for sound to pass one ear and reach the other.