Document 6M8jwkGXXgmEprVVRRGGEYq1

TABLE 45-A PREFERRED FREQUENCIES FOR ACOUSTICAL MEASUREMENTS (American Standard SI 6) Center Frequency (Hz) Bands (Hz) 31 5 630 125 250 500 1.000 2,000 4,000 8,000 16,000 Overall 22 3 to 446 44 6 to 89 2 88 4 to 1770 177 0 to 354 0 354 0 to 707 0 707 0 to 1,414 0 1,414 0 to 2,828 0 2,628 0 to 5,656 0 5,656 0 to 11,3100 11,3100tO 22,620 0 All pass Noise-exposure measurement should be undertaken only by personnel with training and experience in making physical meas urements with electronic equipment (Fig 45-4) (Readers wishing further information on the techniques of noise measurement should consult the references listed under "Noise-Exposure Analysis" at the end of this chapter) Glossary of terms This glossary has been adapted from the Guide for Industrial Audtometnc Techni cians, published by the Safety and Health Services, Employers Insurance of Wausau, Wis, and from American Standard SI 1, Acoustical Terminology AAOO The American Academy of Oph thalmology and Otolaryngology is a profes sional organization of medical specialists who establish standards pertaining to vision and hearing It is also the sponsor of the Sub committee on Noise Research Center AMA HEARING IMPAIRMENT FORMULA The American Medical Association, with the support of the American Academy of Oph thalmology and Otolaryngology, has estab lished a formula for evaluating hearing im pairment based on the average of the hearing levels of the three speech frequencies of 500, 1000, and 2000 Hz Acoustic, acoustical Means contain ing, producing, arising from, actuated by, re lated to, or associated with sound Acoustic is used when the term being qualified desig nates something that has the properties, di mensions, or physical characteristics asso ciated with sound waves, acoustical is used when the term being qualified does not desig nate explicitly something that has properties, dimensions, or physical characteristics ACUITY This sense pertains to the sen sitivity of hearing Air bone gap The difference in deci bels between the heanng levels for a par ticular frequency as determined by air con duction and bone conduction Attenuate To reduce in amount as in audiometry by turning the heanng level dial in units of 10 or 5 decibels in order to obtain a threshold of heanng Attenuation The reduction, expressed in decibels, of the sound intensity at a desig nated first location as compared with sound intensity at a second location, which is acous tically farther from the source Audible range The frequency range over which normal ears hear--approximately 20 Hz through 20,000 Hz Above the range of 20,000 Hz, the term ultrasonic is used Below 20 Hz, the term subsonic is used Audible sound Sound containing fre quency components lying between 15 and 20,000 Hz Audiogram A record of hearing loss or heanng level measured at several different frequencies--usually 500 to 6000 Hz The audiogram may be presented graphically or numencally Audiologist A person trained in the specialized problems of heanng and deafness AUDIOMETER A signal generator or in strument for measunng objectively the sen sitivity of heanng m decibels referred to audiometric zero Audiometric technician A person who is trained and qualified to administer audiometnc examinations Automatic audiometry The method 1517