Variations
There are cases where conventional PTA is not an appropriate or effective method of threshold testing. Procedural changes to the conventional test method may be necessary with populations who are unable to cooperate with the test in order to obtain hearing thresholds. Sound field audiometry may be more suitable when patients are unable to wear earphones, as the stimuli are usually presented by loudspeaker. A disadvantage of this method is that although thresholds can be obtained, results are not ear specific. In addition, response to pure tone stimuli may be limited, because in a sound field pure tones create standing waves, which alter sound intensity within the sound field. Therefore, it may be necessary to use other stimuli, such as warble tones in sound field testing.http://www.emedicine.com/ent/topic311.htm . There are variations of conventional audiometry testing that are designed specifically for young children and infants, such as visual reinforcement audiometry and play audiometry.http://www.ndcs.org.uk/family_support/education_and_health/health/understanding_deafness/#faqblock9 .
Conventional audiometry tests frequencies between 250 hertz (Hz) and 8 kHz, whereas high frequency audiometry tests in the region of 8 kHz-20 kHz. Some environmental factors, such as ototoxic medication and noise exposure, appear to be more detrimental to high frequency sensitivity than to that of mid or low frequencies. Therefore, high frequency audiometry is an effective method of monitoring losses that are suspected to have been caused by these factors. It is also effective in detecting the auditory sensitivity changes that occur with aging. Monteiro de Castro Silva I, Feitosa MA. High frequency audiometry in young and older adults when conventional audiometry is normal. Rev Bras Otorrinolaringol. 2006;72:665-72.
Read more about this topic: Pure Tone Audiometry
Famous quotes containing the word variations:
“I may be able to spot arrowheads on the desert but a refrigerator is a jungle in which I am easily lost. My wife, however, will unerringly point out that the cheese or the leftover roast is hiding right in front of my eyes. Hundreds of such experiences convince me that men and women often inhabit quite different visual worlds. These are differences which cannot be attributed to variations in visual acuity. Man and women simply have learned to use their eyes in very different ways.”
—Edward T. Hall (b. 1914)