Conduction, bone hearing

Frequency Allergic skin reactions to titanium are rare. In 445 patients who had received bone-anchored skin-penetrating tkanium implants for anchorage of facial prostheses or bone-conducting hearing aids, nine had adverse skin reactions around the titanium implants none had delayed hypersensitivity to titanium [65 "]. In these and other cases [66 ] skin reactions have been attributed to infections with Staphylococcus aureus. 

There are three widely accepted routes by which bone-conducted sound stimulates the cochlea. These are the compres-sional, inertial and osseotympanic theories of bone conduction (12). Compressional bone conduction implies that the cochlear shell is compressed slightly in response of the pressure variation caused by a sound. Inertial bone conduction alludes to a relative motion between the ossicular chain and the temporal bone for low frequency vibrations. The osseotympanic theory denotes a mechanism by which relative movement of the skull, with respect to the mandible, sets up pressure variation in the air present in the auditory meatus. Since perception of microwave pulses are correlated with the capacity to hear high-frequency sound, it rules out inertial or osseotympanic bone conduction as potential mechanisms for microwave acoustic effect. 

The primary means for hearing is sound traveling through the outer and middle ear to the inner ear. A small amount of hearing occurs through bone conduction to the inner ear. 

Conductive Hearing Loss. Otosclerosis, inefficient movement of the three bones in the middle ear, results in hearing loss from poor conduction. This disease is treatable with surgery to replace the malformed, misaligned bones with prosthetic pieces to restore conductance of sound waves to the cochlea. 

Vibrations in solid or semi-solid material, or movement in liquid, can produce a series of minute changes in the pressure of the air which is in contact with the material. When this series of small air pressure variations reaches the ear and triggers a message in the auditory nerve, the brain registers this as sound. Sound waves can also travel as vibrations through solid materials such as steel, and Uquid materials such as water. We can hear the sound in steel if we put part of our skull in contact with the steel. This is known as bone conduction of the sound. Some of the pressure waves reaching us through the air can also travel to the inner ear by bone conduction rather than up the ear canal. 

Conductive hearing loss is a form that usually involves an outer or middle ear obstruction that reduces transmission of sound vibrations through air space, bone, or tissue into the middle ear. The treatment for this problem is with medicine or surgery. Hearing aids may also be used. 

A 6-year-old boy with transfusion-dependent P-thalassemia developed unilateral hearing loss shortly after low-dose deferoxamine (dose not specified). Ototoxicity was assumed, but the deficit was later found to be conductive and due to bone marrow proliferation within the ossicular chain as a consequence of the disease. 

A final thought about preparing to speak. Do you know how your voice sounds to others Unless you ve listened to and studied recordings of your voice, you don t know. Decker (1992) explains that, when you talk, the voice you hear is conducted largely through the bones in your head while the voice others hear is transmitted through the air. He says that the recorded voice is the real voice, at least as far as your audiences are concerned. 

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