Hearing Aid Dispenser Written Exam Latest Update Graded A+

Hearing Aid Dispenser Written Exam Latest Update Graded A+ db loss of a perforation of TM 10-15db loss procedure done to fix perforation tympanoplasty or myringoplasty monomeric spots looks like a hole in TM, but reflects light like a mirror. holes that have healed. aka "mirror membranes" average dimentions of an adult eardrum 2.3-2.9cm in length, .7cm in diameters pars tensa lower 4/5 of TM and tight pars flaccida upper 1/5 of TM and flaccid otis externa "swimmers ear" - inflammation of the walls of the EAM. will not cause loss unless swelling blocks canal. treat: warm salt water, drying it, topical antibiotics polyps masses of tissue that grow outward from a surface cholesteatoma non-cancerous tumor in the middle ear. oderous discharge. sometimes perforates upper TM. invasions of skin into the middle ear - sac of concentric rings of protein. causes conductive loss. most dangerous pathology. enlarged canal result of ear surgery. often have no ear drum or ossicular chain. need approval of physician before fitting tympanosclerosis white, chalky calcium deposits caused by degeneration of tissue on eardrum, thicking and scarring from peforations and infections epitympanic cavity attic of middle ear. allows air into mastoid cells of temporal bone. branches several nerves incudotapedial junction top of incus to head of stapes annular ligament footplate of stapes that is held in the oval window speed of sound 700mph or 340 m/s (4x as fast through water, 14x as fast through steel) reflection is an echo or a reverberation reverberation often in a small room, 17m or less, reverbs can mask high frequencies echo heard and perceived later than original sound (more than 1/10s after) absorption aborbs sound. can improve environments w/ reflection or reverb. better in warmth and moist diffraction sharpness in the change in direction of sound, bending. high diffraction=bigger wavelengths (low freq) refraction sound passes through one medium to another, change in speed and wavelength infrasound below audible range of 20 Hz