5 Auditory system

81 dB or greater hearing threshold (“4FAHL”: avg at 0.5, 1, 2, 4 kHz)

146.000 deaf-born children per year*

• 35 dB or greater hearing threshold (avg at 0.5, 1, 2, 4 kHz) in better ear

• 250 million people in the world affected: projected 700 Mio in 2050

• Half of deafness and hearing impairment is avoidable

• Unaddressed hearing loss’ global annual costs US$ 980 billion

• Adult-onset hearing loss is the 2nd leading cause for Years Lived with a Disability (YLD).

• Impaired development of speech, language, cognitive skills in children

• Slow progress in school

• Difficulties in obtaining, performing and keeping an occupation

• Social isolation and stigmatization in all ages and both sexes

• Profound social and economic effects in communities and countries.

At first: only one wire (single channel), not possible to understand speech, but ok with lip reading

sound signal is amplified -> filtered -> envelope=fluctuation -> compression -> electrode transmits

one electrode at a time

Vocoder: Simulate information reduction in CIs

Shows information that is transmitted by a cochlear

Put up an electric field -> cell membrane gets charged (channels open for ions)

pulse usually is followed by an action potential

3: not beeing used, too quiet

Pulse = Stimulus

bucket gets filled and bucket has holes

action potential

with rate adaptation (if there are too many pulses, AP can not keep up - nerve would eventually stop firing)

Numbers=elektrodes are ranked by pitch by patient

rankings are off because nerver fibers have died, so multiple electrodes stimulate the same instead of different

goal: patients can distinguish the electrodes

compression