hearing device Flashcards
Site the three main parts of the ear.
Outer ear - middle ear and inner hear filled with liquid.
Site the steps for sound propagation
outer ear: aerotympanal conduction to the eardrum.
middle ear: sound conduction wia ossicles and sound wolume adjustment (muscle tensor tympani muscle).
Innerear: cochlear transforms acoustic stimuli in electricale xcitation.
Develop the sound propagation in the inner ear.
Vibration of basilar and tectorial membranes. bending of stereocilia of outer hair cells, it amplifies the travveling wave and inner cells get activated. and release neurotransmitters. This stimulates the cochlear or auditory nerve and forwarding to the brain.
What happens when the stereocilia of outer cells hair bends ?
it activates tip links and that open ion channels and allow ions to ented the cells.
With which liquid is filled the cochlea ?
Perilymph and endolymph.
What is the point of liquid fillind in the cochlea ?
faster impedance, transfer vibration to basilar membrane and this transfer to hair cells.
How is built the choclea ?
every point has its own resonance frequency.
What is the fletcher munson curve ?
a measur of sound pressure over frequency for a perceived constant loudness: the higher the frequency is, tje louder is the sound perceived.
Define what’s the percentage of person suffering from impairment and site the reasons ?
10 percent
Presbycusis (degeneration of cortico organ, disorder in blood supply…°, socio (noise), toxic injuries of the inner ears or inherited defectie hearing.
What are the challenges surrounding hearing aids.
-Adjustement of acoustic noise to device, adjustement of device signal to the ear, biocompatible material, easy to handle, aesthetic, fixation, adaptation to hearing impairment.
Site the component of non implanted hearing device.
microphone , pre amplifier, A/D converter, digital signal processor (DSP), D/A, amplifier , loudspeaker, battery.
Site three main solutions for implanted hearing aids:
middle ear implant system, bone conduction implant system or cochlear implant.
What is the aim of cochlear implant ?
Replaced function of harmed inner ear. this is the first successful replacement of human sense. ut the cochlear auditory nerve must be funcitonnal.
Site the components of cochlear implants.
External component : ear attachement, microphone, processor unit, operating switch, display, control unit with battery case, transmitter coil.
Implant : reference electrode, electrode array, receiver coil/electronics and a magnet.
Site the material of the cochlear implant for the electrode array/housing and encapsulation.
Platinum electrode sites, titanium/ceramics, silicone rubber.
