1. INTRODUCTION TO AUDIOLOGY (SPHS 1100)
WEEK 4 POWER POINT
TOPICS
TYPES OF HEARING LOSS
CAUSES OF HEARING LOSS
DEGREE OF HEARING LOSS
AUDIOGRAM

2. GOALS and OBJECTIVES GOAL
Learner will understand the different topics related to Audiology
OBJECTIVES
TLW identify the causes of hearing loss. (cognitive)
TLW differentiate types of hearing loss. (cognitive)

3. TYPES OF HEARING LOSS
The type of hearing loss depends up on where in the ear problem occur. The three main types are
Conductive hearing loss.
Sensorineural hearing loss.
Mixed hearing loss

4. TYPES OF HEARING LOSS

5. TYPES OF HEARING LOSS Conductive hearing loss
A problem in the outer or middle ear causes conductive hearing loss.
A decrease in strength of a sound is called attenuation.
Conductive hearing loss involves reduction in sound level, or the ability to hear faint sounds.
Persons with conductive hearing loss find that their sensitivity to sounds that are introduced by air conduction is impaired by such a blockage.

6. TYPES OF HEARING LOSS
If the sound is introduced by bone conduction, it passes the obstacle and goes directly to the sensorineural mechanism.
The inner ear and other sensorineural structures will be unimpaired and hearing by bone conduction will be normal.
This occurs when sound is not able to reach cochlea. This is due to malformation of ear canal.
This problem can be fixed through simple surgical procedures. 

7. TYPES OF HEARING LOSS Sensorineural hearing loss
A problem in the inner ear can cause sensorineural hearing loss .
It is also known as nerve-related hearing loss as the damaged nerves in the inner ear can cause the loss.  
These losses cannot be fixed through surgical procedures.
Sensorineural hearing loss involves reduction in sound level, inability to hear sounds and  also affects speech understanding .

8. TYPES OF HEARING LOSS Mixed hearing loss
Hearing loss which is caused by combination of conductive and sensorineural hearing loss.
The problem might be both in the outer or middle ear and in the inner ear.

9. CAUSES OF HEARING LOSS Causes of conductive hearing loss
Malformation of outer ear, ear canal or middle ear structures.
Problems associated with middle ear pathology such as fluid in the middle ear from colds and allergies
Poor Eustachian tube function
Ear infection, perforated eardrum and benign tumors.
Impacted earwax
Foreign body in the ear
Otosclerosis which is abnormal growth of bone of the middle ear

10. CAUSES OF HEARING LOSS Causes of sensorineural hearing loss
There are two types of causes
Prenatal or Perinatal causes
Postnatal causes

11. CAUSES OF HEARING LOSS PRENATAL OR PERINATAL CAUSES
Infections such as rubella, herpes, toxoplasmosis, syphilis and cytomegalovirus.
Hearing loss that runs in family.
Asphyxia or lack of oxygen at birth.
Birth weight of less than 1500 grams.
Defects of head and neck.

12. CAUSES OF HEARING LOSS POSTNATAL CAUSES Exposure to loud noise.
Bacterial Meningitis
Ototoxicity caused by exposure to drugs
Physical damage to head or ear
Hearing loss due to aging which is called as presbycusis

13. Other descriptors associated with hearing loss
Bilateral
Hearing loss in both ears.
Unilateral
Hearing loss in one ear and normal in other ear.
Symmetrical
In symmetrical hearing loss the degree and configuration are similar in both ears.
Asymmetrical
In asymmetrical hearing loss the degree and configuration are different in both ears.

14. Other descriptors associated with hearing loss
Progressive versus sudden
In progressive hearing loss the loss becomes worse over time where as in sudden the loss happens quickly.
Fluctuating versus stable
 Fluctuating hearing loss changes over time, sometimes getting better sometimes getting worse. Stable hearing loss does not change over time and remains the same.

15. Degree of hearing loss
Degree of hearing loss refers to severity of hearing loss.
According to Clark J.G. (1981) the degree of hearing loss is classified as
Normal-  -10 to 15 dBHL
Slight –  16 to 25 dBHL
Mild- 26 to 40 dBHL
Moderate- 41 to 55 dbHL
Moderately severe- 56 to 70 dBHL
Severe- 71 to 90 dBHL
Profound- 91+ dBHL

16. AUDIOGRAM
An audiogram is a graph illustrating a person’s usable hearing and the amount of hearing loss that an individual has for each ear.
The frequency or pitch of the sound is referred to in Hertz.
The intensity or loudness of sound is measured in decibels.

17. Example of Audiograms with different degree of hearing loss

18. References Images http://www.dallashear.com/types-of-hearing-loss.html
cFamilyServices/Audiology/Forfamilies/readaudiogra m.htm