Download Presentation title

The ear and causes of
hearing loss
Learning objectives
• to describe how the ear works
• to identify the different types of hearing loss
• To explain common causes of hearing loss
• Relevant for: Assignment 1a
(deadline 30th Nov 14)
City Lit
The ear
What is sound?
A vibrating source causes particles of air to vibrate in a
wave form
The sound wave varies in:
- frequency (pitch)
- amplitude/intensity (loudness)
City Lit
Sound waves
frequency (pitch)
amplitude (loudness)
City Lit
City Lit
Outer, middle and inner ear
City Lit
Hair cells in the cochlea
City Lit
Damaged hair cells
City Lit
Hearing sound through air
http://www.youtube.com/watch?v=stiPMLtjYAw
City Lit
Hearing sound through the skull
City Lit
Types of hearing loss
Conductive
Sensori-neural
Mixed
Central processing
Non organic
City Lit
Conductive hearing loss
The journey of the sound waves from the outer
ear to the cochlea is impeded or obstructed
Can affect either the outer and/or the middle ear
City Lit
Types of hearing loss
City Lit
Sensori-neural hearing loss
Results from damage to the cochlea and/or the
auditory nerve
Affects the inner ear
Can affect how well a person discriminates and
understands speech sounds
City Lit
Damaged hair cells
City Lit
Sensori-neural hearing loss
City Lit
In groups/pairs:
How many different causes of hearing loss
can you think of?
City Lit
Some causes of conductive hearing loss
Wax or foreign bodies
Malformation or damage to outer or middle ear
Scarred or perforated eardrum
Eustachian Tube dysfunction
Otosclerosis
Atresia
Trauma
Otitis Externa and Otitis Media
Cholesteatoma
City Lit
Some causes of
sensori-neural hearing loss
Anoxia
Noise induced (NIHL)
Prematurity
Viral
Mumps, Measles, Rubella
Ménière’s disease
Meningitis
Acoustic neuroma
Vascular
Brain tumour
Trauma
Neurofibromatosis (NF2)
Ototoxic drugs
Presbyacusis
(age –related ARHL)
Genetic
City Lit
Causes of hearing loss
Syndromes
e.g. Ushers, Downs, Treacher Collins, Alports
Central processing disorders
e.g. auditory processing disorder (APD)
other cognitive difficulties
Non-organic hearing loss
e.g. malingering =deliberately faking a hearing loss
psychogenic = arising from psychological factors
City Lit
Explain to your partner
1. How do we hear (with normal hearing)?
2. What is a conductive hearing loss? What is a sensorineural loss?
3. Why will someone with a sensori-neural hearing loss
probably have difficulty distinguishing speech?
4. Draw lines on the diagram to separate the three parts of
the ear
City Lit
Useful sources
Action on Hearing Loss www.actiononhearingloss.org.uk
Hearing Link
City Lit Document Title
http://hearinglink.org/