Noise induced hearing loss Predisposing factors: Predisposing factors: Drug use (aspirin) Drug use (aspirin) Gender Gender Cause: Exposure to noise Cause: Exposure to noise Acoustic trauma: Damage due to loud impulsive noise Acoustic trauma: Damage due to loud impulsive 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 (OSHA, 1983) Relationship between noise level and duration of exposure (OSHA, 1983) 85 dB A: 8 hours 85 dB A: 8 hours 90 dB A: 4 hours 90 dB A: 4 hours 95 dB A: 2 hours 95 dB A: 2 hours 105 dB A: 30 minutes 105 dB A: 30 minutes

Audiometric findings Sensorineural hearing loss Sensorineural hearing loss Usually progressive with continued noise exposure Usually progressive with continued noise exposure Characteristic notch around 4000 Hz Characteristic notch around 4000 Hz Tinnitus matched to frequencies around 3-6 kHz Tinnitus matched to frequencies around 3-6 kHz

Measures to prevent NIHL Avoid noise exposure, especially if on certain types of medication Avoid noise exposure, especially if on certain types of medication Hearing protection Hearing protection Monitor hearing loss periodically Monitor hearing loss periodically

Presbycusis Age-related hearing loss Age-related hearing loss Progressive, sensorineural Progressive, sensorineural Effects first seen in high frequencies Effects first seen in high frequencies Age-related changes occur not only in cochlea Age-related changes occur not only in cochlea Often: Speech-understanding difficulties Often: Speech-understanding difficulties

Progression of hearing loss with age in females and males

Méniére disease Disease that originates in the labyrinth Disease that originates in the labyrinth Classic symptoms: Hearing loss, tinnitus, and vertigo Classic symptoms: Hearing loss, tinnitus, and vertigo Symptoms can be paroxysmal, and are usually progressive. Symptoms can be paroxysmal, and are usually progressive. Probable causes: Endolymphatic hydrops, others Probable causes: Endolymphatic hydrops, others Treatment: Diuretics to limit fluid retention, diet control, sedatives, vestibular suppressants, surgery. Treatment: Diuretics to limit fluid retention, diet control, sedatives, vestibular suppressants, surgery.