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Author

Warren E. Blazier

Bio: Warren E. Blazier is an academic researcher. The author has contributed to research in topics: Noise. The author has an hindex of 1, co-authored 1 publications receiving 64 citations.
Topics: Noise

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Journal ArticleDOI
TL;DR: Evidence suggests that a number of adverse effects of noise in general arise from exposure to low-frequency noise: Loudness judgments and annoyance reactions are sometimes reported to be greater for low- frequency noise than other noises for equal sound-pressure level.
Abstract: The sources of human exposure to low-frequency noise and its effects are reviewed. Low-frequency noise is common as background noise in urban environments, and as an emission from many artificial sources: road vehicles, aircraft, industrial machinery, artillery and mining explosions, and air movement machinery including wind turbines, compressors, and ventilation or air-conditioning units. The effects of low-frequency noise are of particular concern because of its pervasiveness due to numerous sources, efficient propagation, and reduced efficacy of many structures (dwellings, walls, and hearing protection) in attenuating low-frequency noise compared with other noise. Intense low-frequency noise appears to produce clear symptoms including respiratory impairment and aural pain. Although the effects of lower intensities of low-frequency noise are difficult to establish for methodological reasons, evidence suggests that a number of adverse effects of noise in general arise from exposure to low-frequency noise: Loudness judgments and annoyance reactions are sometimes reported to be greater for low-frequency noise than other noises for equal sound-pressure level; annoyance is exacerbated by rattle or vibration induced by low-frequency noise; speech intelligibility may be reduced more by low-frequency noise than other noises except those in the frequency range of speech itself, because of the upward spread of masking. On the other hand, it is also possible that low-frequency noise provides some protection against the effects of simultaneous higher frequency noise on hearing. Research needs and policy decisions, based on what is currently known, are considered.

410 citations

01 May 2003
TL;DR: In this paper, the authors provide a free-text for any format or medium provided that it is reproduced accurately and not used in a misleading context, and the material must be acknowledged as Crown copyright with the title and source of the publication specified.
Abstract: This publication (excluding the logo) may be reproduced free of charge in any format or medium provided that it is reproduced accurately and not used in a misleading context. The material must be acknowledged as Crown copyright with the title and source of the publication specified.

227 citations

Journal ArticleDOI
TL;DR: New measurements of the intelligibility of speech in conditions representative of elementary school classrooms found that for conditions of constant signal-to-noise ratio, intelligibility scores increased with decreasing reverberation time, but for conditions including realistic increases in speech level with varied reverberationTime, intelligible scores were near maximum for a range of reverberation times.
Abstract: This paper reports new measurements of the intelligibility of speech in conditions representative of elementary school classrooms. The speech test material was binaurally recorded in simulated classroom conditions and played back to subjects over headphones. Subjects included grade 1, 3, and 6 students (6, 8, and 11 year olds) as well as adults. Recognizing that reverberation time is not a complete descriptor of room acoustics conditions, simulated conditions included realistic early-to-late arriving sound ratios as well as varied reverberation time. For conditions of constant signal-to-noise ratio, intelligibility scores increased with decreasing reverberation time. However, for conditions including realistic increases in speech level with varied reverberation time for constant noise level, intelligibility scores were near maximum for a range of reverberation times. Young children's intelligibility scores benefited from added early reflections of speech sounds similar to adult listeners. The effect of varied reverberation time on the intelligibility of speech for young children was much less than the effect of varied signal-to-noise ratio. The results can be used to help to determine ideal conditions for speech communication in classrooms for younger listeners.

152 citations

Journal ArticleDOI
TL;DR: Significant differences were seen in comprehension scores as a function of age and condition; both increasing background noise and reverberation degraded performance in comprehension tasks compared to minimal differences in measures of sentence-recognition.
Abstract: The potential effects of acoustical environment on speech understanding are especially important as children enter school where students’ ability to hear and understand complex verbal information is critical to learning. However, this ability is compromised because of widely varied and unfavorable classroom acoustics. The extent to which unfavorable classroom acoustics affect children’s performance on longer learning tasks is largely unknown as most research has focused on testing children using words, syllables, or sentences as stimuli. In the current study, a simulated classroom environment was used to measure comprehension performance of two classroom learning activities: a discussion and lecture. Comprehension performance was measured for groups of elementary-aged students in one of four environments with varied reverberation times and background noise levels. The reverberation time was either 0.6 or 1.5 s, and the signal-to-noise level was either +10 or +7 dB. Performance is compared to adult subjects as well as to sentence-recognition in the same condition. Significant differences were seen in comprehension scores as a function of age and condition; both increasing background noise and reverberation degraded performance in comprehension tasks compared to minimal differences in measures of sentence-recognition.

112 citations

Journal ArticleDOI
TL;DR: In this article, the results of a wide acoustic environment survey were presented, where sound pressure measurements were carried out in a group of offices and the measurements lasted for five minutes and the resulting noise spectra were used to calculate the most significant acoustic parameters.

53 citations