Noise induced hearing lossNoise induced hearing loss

Predisposing factors:Predisposing factors:

Drug use (aspirin)Drug use (aspirin)GenderGender

Cause: Exposure to noiseCause: Exposure to noise

Acoustic trauma: Damage due to loud Acoustic trauma: Damage due to loud impulsive noiseimpulsive noise

Two forms of NIHL Two forms of NIHL

Temporary threshold shift (TTS)Temporary threshold shift (TTS)

Permanent threshold shift (PTS)Permanent threshold shift (PTS)

Relationship between noise level and duration of exposure Relationship between noise level and duration of exposure (OSHA, 1983)(OSHA, 1983)

85 dB A: 8 hours85 dB A: 8 hours 90 dB A: 4 hours90 dB A: 4 hours 95 dB A: 2 hours95 dB A: 2 hours 105 dB A: 30 minutes105 dB A: 30 minutes

Audiometric findingsAudiometric findings

Sensorineural hearing lossSensorineural hearing loss

Usually progressive with continued noise Usually progressive with continued noise exposureexposure

Characteristic notch around 4000 HzCharacteristic notch around 4000 Hz

Tinnitus matched to frequencies around 3-Tinnitus matched to frequencies around 3-6 kHz6 kHz

Measures to prevent NIHLMeasures to prevent NIHL

Avoid noise exposure, especially if on Avoid noise exposure, especially if on certain types of medicationcertain types of medication

Hearing protectionHearing protection

Monitor hearing loss periodicallyMonitor hearing loss periodically

PresbycusisPresbycusis

Age-related hearing lossAge-related hearing loss

Progressive, sensorineuralProgressive, sensorineural

Effects first seen in high frequenciesEffects first seen in high frequencies

Age-related changes occur not only in Age-related changes occur not only in cochleacochlea

Often: Speech-understanding difficulties Often: Speech-understanding difficulties

Progression of hearing loss with age in Progression of hearing loss with age in females and malesfemales and males

Females

0

10

20

30

40

50

60

70

80

90

100

250 500 1000 2000 4000 6000 8000

Frequency (Hz)

dB

HL

(A

NS

I, 1

96

9)

60-64

65-69

70-74

75-79

80-84

85-89

Males

0

10

20

30

40

50

60

70

80

90

100

250 500 1000 2000 4000 6000 8000

Frequency (Hz)

dB

HL

(A

NS

I, 1

96

9)

60-64

65-69

70-74

75-79

80-84

85-89

Méniére diseaseMéniére disease

Disease that originates in the labyrinthDisease that originates in the labyrinth

Classic symptoms: Hearing loss, tinnitus, and Classic symptoms: Hearing loss, tinnitus, and vertigovertigo

Symptoms can be paroxysmal, and are usually Symptoms can be paroxysmal, and are usually progressive.progressive.

Probable causes: Endolymphatic hydrops, othersProbable causes: Endolymphatic hydrops, others

Treatment: Diuretics to limit fluid retention, diet Treatment: Diuretics to limit fluid retention, diet control, sedatives, vestibular suppressants, surgery.control, sedatives, vestibular suppressants, surgery.