CSD 2230 HUMAN COMMUNICATION DISORDERS

1. CSD 2230HUMAN COMMUNICATION DISORDERS Topic 5 Hearing Disorders and Hearing Loss Introduction to Sound Types of Hearing Loss

2. Sound System Source • Any vibrating object Medium • Any gas, liquid or solid Receiver • anything designed to detect the vibrations within the medium originating from the source

3. A Common Sound System Illustration of the distribution of molecules surrounding a source in an instant in time

4. Condensation and Rarefaction Bands of condensation and rarefaction emanating from a sound source

5. Propagation of a Disturbance Through a Medium Notice that as time goes on, molecules farther from the source become affected by the disturbance.

6. Frequency Rate of pressure change as a function of time Measured as cycles/sec or Hertz The primary determiner of pitch Intensity Magnitude of the pressure change Measured as the decibel (dB) The primary determiner of loudness Important Physical Characteristics of Sound

7. Frequency and Intensity Sounds a and c share the same frequency and sounds b and c share the same intensity

8. Loudness and Intensity Here are some common sounds and their decibel equivalents

9. The Hearing System Basic schematic diagram of the entire auditory system

10. Putting It All Together….

11. Types of Hearing Impairment • A loss of sensitivity • Auditory nervous system pathology

12. Important Terms • Time of onset • Congenital: present at birth • Acquired: obtained after birth • Adventitious: acquired after birth

13. Important Terms • Time Course • Acute: sudden onset/short duration • Chronic: long duration • Sudden: rapid onset • Gradual: changes slowly over time

14. Important Terms • Time Course • Temporary: limited duration • Permanent: irreversible • Progressive: advancing • Fluctuating: changes in degree over time

15. Important Terms • Number of Ears Involved • Unilateral: Just one • Bilateral: Both

16. Hearing Sensitivity Loss • “The ear is not as sensitive as normal in detecting sound” • Types: • Conductive • Sensorineural • Mixed

17. Conductive Hearing Loss • “Caused by an abnormal reduction or attenuation of sound as it travels from the outer ear to the cochlea”

18. Sensorineural Hearing Loss • “Caused by a failure in the cochlea to transduce the sound from the middle ear to neural impulses in the VIII Nerve.”

19. Sensorineural Hearing Loss • Implications include: • A reduction in the sensitivity of the receptor cells in the cochlea • A reduction in the frequency resolving power of the cochlea • A reduction in the dynamic range of the system

20. Mixed Hearing Loss • “A loss with both a conductive and sensorineural component.”

21. Types of Hearing Impairment • A loss of sensitivity • Auditory nervous system pathology

22. Auditory Nervous System Impairment • Causes: • Disease • Disordered auditory nervous system development

23. Auditory Nervous System Impairment • Kinds: • Retrocochlear disorders • Central auditory processing disorders

24. Auditory Nervous System Impairment • Auditory Characteristics: • Reduced ability to understand speech in a noise background • Problems understanding speech with reduced redundancy • Problems with localization and lateralization • Problems processing normal or altered temporal cues

25. Auditory Pathologies Outer and middle ear disorders • Conductive pathologies Cochlear disorders • Sensorineural pathologies Central auditory disorders • Central auditory pathologies

26. Outer and Middle Ear Disorders • Structural defects due to embryologic malformations • Structural changes secondary to infection or trauma

27. Outer Ear Disorders • Microtia and atresia

28. Microtia • “an abnormal smallness of the auricle”

29. Atresia • “the absence of an opening of the external canal”

30. Outer Ear Disorders • Microtia and atresia • Impacted cerumen • Perforation of the tympanic membrane

31. Outer Ear Disorders • Microtia and atresia • Impacted cerumen • Perforation of the tympanic membrane • Other

32. Otitis Media Most common cause of transient conductive hearing loss in children Inflamation of the middle ear Caused by eustachian tube failure Middle Ear Disorders

33. Ways to Classify Otitis Media • With or without effusion • Fluid type • Serous • Suppurative • Mucoid

34. Ways to Classify Otitis Media • With or without effusion • Fluid type • Duration • Acute • Chronic • Subacute • Persistent • Recurrent

35. Otitis Media Facts • 76-95% of all kids will have one episode of OM by age 6 • Prevalence is highest during the first two years of life • 50% of all kids with one episode before their first birthday will have 6 or more bouts within two years • Most episodes occur in winter and spring • Risk factors • Cleft palate • Down syndrome • Native Americans • Urban poor • Day care • Secondhand smoke

36. Middle Ear Disorders • Otitis media • Otosclerosis

37. Otosclerosis • “a bone disorder that affects the stapes and the bony labyrinth of the inner ear. The disease process is characterized by resorption of bone and new spongy formation around the stapes and oval window”

38. Otosclerosis • Facts: • Hereditary • Women are more likely to develop the disorder • Usually bilateral • progressive

39. Middle Ear Disorders • Otitis media • Otosclerosis • Cholesteatoma

40. Cholesteatoma • “an epithelial pocket that forms on the tympanic membrane. Once the pocket forms, the normal shedding of epithelium results in growth of the tumor”

41. Middle Ear Disorders • Otitis media • Otosclerosis • Cholesteatoma • Other • Physical trauma • Barotrauma • Middle ear tumors • Glomus tumor

42. Cochlear Disorders • Syndromes and inherited disorders • Syndromic disorders • Nonsyndromal disorders

43. Syndromes and Inherited Disorders Resulting in Sensorineural Hearing Loss

44. Types of Nonsyndromic Disorders • Dominant • Dominant progressive • Dominant progressive with adult onset • Recessive hereditary SNHL • X-linked

45. Cochlear Disorders • Syndromes and inherited disorders • Noise induced hearing loss

46. Noise Induced Hearing Loss • The degree of SNHL depends on • The intensity of the noise • The spectral composition of the noise • The duration of exposure • Individual susceptibility

47. OSHA Damage Risk Criteria

48. Cochlear Disorders • Syndromes and inherited disorders • Noise induced hearing loss • Other trauma • Infections

49. Infections • Congenital • Cytomegalovirus • HIV • Rubella • Syphilis • Toxoplasmosis

50. Infections • Acquired • Herpes Zooster Oticus (Chicken Pox) • Mumps • Syphilis