Sensorineural vs conductive hearing loss tests,sermon tito 2 11 14 year,how do i get rid of a buzzing in my ear - Step 1

Author: admin, 11.02.2016. Category: Cause Of Ringing In Ears

Sound "Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations” – Wikipedia.
Effect of weather Because sound is carried by air compression and decompression, sound travelling can be affected by temperature Eg.
The middle ear (function?) Efficient transfer of sound from the air to the fluid in the cochlea (inner ear) –Otherwise, sound would mostly be reflected. The middle ear Acoustic reflex Muscles in the middle ear (tensor tympani) can contract to pull the stapes away from the oval window, and therefore reduce drastically transmission.
The Cochlea Shaped like a spiral (no functional reason – space economy?) Filled with uncompressible fluids Rigid, bony walls ? transmit sound pressure without loss! Basilar membrane (cont’d) Mechanical properties of BM varies across length: –Narrow & stiff at base –Wider & less stiff at apex ? position of the peak depends on frequency! Stereocilia (cont’d) Transforms mechanical movements into neural activity Stereocilia are joined by fine links (“tip links”) Deflection of the stereocilia apply tension to those links ? opens “transduction channels” ? flow of potassium ions, voltage alteration, etc.

Inner hair cells Each inner hair cell is connected ~ 20 neurons Most (all?) information is transferred by inner hair cells.
Otoacoustic emissions Experiments by Kemp (1978): if a click is sounded next to the ear, it is possible to detect a sound coming out of the ear (using a microphone sealed into the ear canal) –Reflexions?
Neurons in the auditory nerve Approximately 30,000 neurons in each auditory nerves (left,right) Study this using fine tipped micro-electrodes to record voltage in single cells Most neurons fire spontaneously (0-150Hz) Most neurons are tuned to specific frequencies.
Minimum Audible Pressure An absolute threshold is the minimum detectable level of a sound, in the absence of other external sounds. Absolute Thresholds Depends on people: individuals may vary by up to 20dB and have “normal” hearing. Sensorineural hearing loss Due to defects in: –cochlea –auditory nerve –higher centers in the brain.
Frequency that gives best response at a point of the BM is called Characteristic Frequency (CF) for this point.

Phase locking: spikes occur at specific phase of the stimulating waveform ? temporal regularity. Depends on set-up: important to define precisely how the intensity is measured –Probe microphone (ideally close to the eardrum) Usually using headphones. MAP MAF is binaural, MAP is monaural MAF factors in the head, pinna & meatus effects (broad resonance) Thresholds increase rapidly at very high and very low frequencies ? transmission characteristics of the middle ear! In response to a steady frequency, all points vibrate at the same frequency ? some point with greater amplitude.

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