Module 4: CSD 232

Sound

Consists of vibrations through a medium.

Longitudinal Wave (Ears)

A wave in which the motion of the medium is parallel to the direction of the wave.

Transverse Wave (eyes)

A wave in which the motion of the medium is perpendicular to the direction of the wave.

Compression

When particles come together in a sound wave.

Rarefaction

When particles move apart in a sound wave.

Frequency

The number of cycles of oscillation per second, measured in Hertz (Hz).

Loudness

How much movement an individual makes determines the intensity, The amplitude, or the intensity of vibration (measured in dB and varied units.

Audiogram

A chart that displays an individual's hearing thresholds at various frequencies.

Conductive Hearing Loss

Hearing loss is caused by problems in the outer or middle ear. (You can experience this type of hearing loss without harm)

Sensorineural Hearing Loss

Hearing loss caused by problems in the inner ear or beyond, usually permanent.

Mixed Hearing Loss

Combination of conductive and sensorineural hearing loss present in the same ear.

Central Auditory Processing Disorder (CAPD)

A disorder that affects the brain's ability to process auditory information, despite normal hearing thresholds.

Temporary Threshold Shift (TTS)

A short-term hearing loss that occurs after exposure to loud noise but recovers over time.

Permanent Threshold Shift (PTS)

A long-term or permanent hearing loss due to exposure to intense noise.

Presbycusis

Age-induced hearing loss

Types of threshold shifts

Includes prolonged exposure to loud sounds, Hg loss is measurable in terms of threshold shifts, If the hearing recovers, the shifts are temporary (aka Temporary Threshold shift or TTS), If the hearing fails to recover, the shifts are permanent (Permanent Threshold Shift or PTS)

Acoustic Trauma

A form of noise-induced hearing loss caused by exposure to impulsive sounds.

Noise Control Strategies

Control at source: Modifying equipment. Protect at ear level: Ear plugs. Control Transmission: Absorb sounds (carpet, acoustic tiles)

Noise standards

NIOSH standards for max exposure, 85 dBA for 8 hours. If you turn up loudness by 3 dB or “double intensity”. Down the time by half.

Types of changes in cochlea

Biological changes in the hair cells. Physical dislodging of hair cells

Risks associated with thresholds

Aspirin may increase TTS, Men are more likely to end up with NIHL, and Children exposed to loud toys are at risk of HL, The individual size of the cars can vary the sound level by up to 25 dB

Central Auditory Processing Disorders

CAPD problems typically affect brainstem pathways/auditory cortex (auditory nervous system), Hearing thresholds may be normal, but the ability to use and interrupt auditory information is lost

Degrees of Hearing Loss

Normal hearing, Mild hearing, Moderate hearing, Moderately severe, Severe hearing loss, Profound hearing loss (cannot use hearing to communicate at all, deaf)

Gender difference

Men have poorer sensitivity above 1kHz. Women have poorer sensitivity below 1kHz

Treatment

• Speak slower rather than louder when talking to people who have presbycusis

  • Use hearing Aid, Body aid, BTE (BEHIND THE EAR), ITC(IN THE CANAL), ITE (IN THE EAR), CIC Eyeglass   BC. Left ear is blue right ear is red