In: Snoring5 Aug 2014
The testing room had a background noise level below 35 dBA (sound pressure measurement in decibels employing the A-weighting network that yields the response of the human ear), with an ambient noise level always > 10 decibels (dB) below the measured signal, and a reverberation time of < 1.5 s. These parameters ensured that the sound that was measured was generated by the patient. The microphone used to record the snoring sounds was suspended 24 inches above the surface of the patient’s bed. This arrangement allowed a noninvasive recording approach and, more importantly, a standardized distance that approximated the distance between sleeping bed partners. Based on acoustic measurements, it was estimated that a variation of not more than ± 3 dBA would occur if a patient changed position by rolling side to side. The recording equipment had a frequency response of ± 10 dB from 20 to 12,000 Hz, and a 70-dB dynamic range. The system was acoustically calibrated with a known test tone before each study. Allergies pills Reading here A noise exposure analyzer (model NA850A; Illbruck USA Inc; Minneapolis, MN) was used for all snoring sound measurements. This instrument examined the sound pressure level of a random noise source at 1-s intervals and classified it into 1-dB steps according to the amplitude exceeded. The sound generated by the subject during sleep was identified as snoring by the monitoring technical personnel.
The following patient information was entered into a computer database that was part of measurement apparatus: name, hospital medical record number, test date, duration of testing, distribution of A-weighted dB values over time, and the average A-weighted dB level (Leq). Three peak dB levels were selected for analysis from the resulting continuous distribution of the A-weighted dB values over time: the dBA level exceeded for 1% of the test period that represents the maximum peak level measured during the testing period (L1), the dBA level exceeded for 5% of the test period (L5), and the dBA level exceeded for 10% of the test period (L10).
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