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Technology for a Quieter America (2010) / Chapter Skim
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Appendix I: Glossary of Selected Terms
Pages 175-180

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From page 175...
... * Active control -- Reducing sound and secondary sources of excitation to cancel, or at least reduce, the response of a sys - NOTE: Day average sound level in decibels is related tem to prime noise sources; also to suppress self-excitation to the corresponding day sound exposure level, LEd, acoscillations of an unstable system.
From page 176...
... Conduc pressure-squared level; in common practice, however, tive hearing loss: Hearing loss caused either by blockage called sound pressure level, unless an ambiguity results from so doing. of the external ear or by disease or damage in the middle ear, so that the signal amplitude reaching the inner ear is †Effective perceived noise level -- Level of the time integral reduced.
From page 177...
... = L peq , T + 10 log   dB,  T0  NOTE: Procedures for computing perceived noise level are stated in Federal Aviation Regulation Part 36, Noise where p(t) is the instantaneous sound pressure, p0 is the refer Standards: Aircraft Type and Airworthiness Certifica ence sound pressure, and Lpeq.T is the equivalent continuous tion, Appendix B, and in International Civil Aviation sound pressure level.
From page 178...
... exposure is the pascal-squared second. †Sound-level meter -- Device used to measure sound pres†Sound exposure level -- Ten times the logarithm to the sure level with a standardized frequency weighting and base 10 of the ratio of a given time integral of squared in indicated exponential time weighting for measurements of stantaneous A-weighted sound pressure, over a stated time sound level, or without time weighting for measurements of interval or event, to the product of the squared reference time-average sound pressure level or sound exposure level.
From page 179...
... * Weighting network -- Electronic filter in a sound-level †Speech interference level -- One-fourth of the sum of the meter that approximates, under defined conditions, the freband sound pressure levels for octave bands with nominal quency response of the human ear.


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