Limitation of Sight and Hearing
INTRODUCTION
Defects of Hearing •Hearing defects means ear is not working correctly or as well as it should. •It may occur in more than one part of the ear. •1. DEAF-full or partial decrease in the ability to detect or understand sounds.
Deaf usually caused by :
- Eardrum is torn-cannot function
- Ossicle bone fused together-can’t vibrate
- Auditory nerve damaged by loud sound
- Cochlea damage due to sickness/ drugs •2. Temporary hearing loss-build-up of earwax •3. Presbycusis- hearing loss related to aging and other factors.
Correcting hearing defects •Syringes and warm water –remove wax •Replace damaged ossicles •Surgery- damaged eardrums •Electronic gadgets - implantation
Limitation of Hearing •Definition: The range of sound that human can hear. 20-20000Hertz •Limitations of hearing varies with people
Range of hearing in different individual •Children have eardrums that are more elastic. As a result, they can hear better. •As people age, their hearing deteriorates. Their eardrum become less elastic. The range of sound frequencies that they can detect decrease. Their ability to hear high-pitched sounds decrease. •Person exposed to constant loud noise experiences a loss of hearing-range of hearing is smaller than normal people.
Limitation of Sight
A. Blind spot
•At certain distance from the eye, some object that you can see previously may disappear, after certain moment, it will reappear.
•This phenomenon occurs because the image of the object has fallen onto the blind spot in your eye.
•This blind spot does not have any photoreceptors. As result, the image of the cross that falls on this spot cannot be detected, and that's why you can't see it.
B. Optical illusion
•Optical illusion are caused by disturbances to the nerve impulses going to the brain.
•The disturbances may caused by the object or condition around the object.
•The brain cannot accurately interpret the information sent by the receptors in eye.
•That’s why you will incorrectly
Defects of Hearing •Hearing defects means ear is not working correctly or as well as it should. •It may occur in more than one part of the ear. •1. DEAF-full or partial decrease in the ability to detect or understand sounds.
Deaf usually caused by :
- Eardrum is torn-cannot function
- Ossicle bone fused together-can’t vibrate
- Auditory nerve damaged by loud sound
- Cochlea damage due to sickness/ drugs •2. Temporary hearing loss-build-up of earwax •3. Presbycusis- hearing loss related to aging and other factors.
Correcting hearing defects •Syringes and warm water –remove wax •Replace damaged ossicles •Surgery- damaged eardrums •Electronic gadgets - implantation
Limitation of Hearing •Definition: The range of sound that human can hear. 20-20000Hertz •Limitations of hearing varies with people
Range of hearing in different individual •Children have eardrums that are more elastic. As a result, they can hear better. •As people age, their hearing deteriorates. Their eardrum become less elastic. The range of sound frequencies that they can detect decrease. Their ability to hear high-pitched sounds decrease. •Person exposed to constant loud noise experiences a loss of hearing-range of hearing is smaller than normal people.
Limitation of Sight
A. Blind spot
•At certain distance from the eye, some object that you can see previously may disappear, after certain moment, it will reappear.
•This phenomenon occurs because the image of the object has fallen onto the blind spot in your eye.
•This blind spot does not have any photoreceptors. As result, the image of the cross that falls on this spot cannot be detected, and that's why you can't see it.
B. Optical illusion
•Optical illusion are caused by disturbances to the nerve impulses going to the brain.
•The disturbances may caused by the object or condition around the object.
•The brain cannot accurately interpret the information sent by the receptors in eye.
•That’s why you will incorrectly