煤粉风机噪声治理

针对喷煤煤粉风机产生的噪声,尤其是排风管出口噪声的治理,结合现场实际情况,设计并实施了切实可行的治理方案,明显降低了出口噪声。     

大冶铁矿球团鼓风机房噪声控制治理

主要介绍了大冶铁矿球团厂竖炉鼓风机房噪声治理的过程,其中包括噪声的诊断分析,控制治理方案,设计特点以及治理前后的情况对比和需要进一步完善的地方。     

安钢烧结主风机噪声治理实践

介绍了安钢烧结厂针对大功率、高负压烧结主风机噪声特性,在90／105m^2烧结机噪声治理中所采取的措施。治理后作业环境达到了国家工业企业噪声卫生标准的要求,同时也满足了主风机的运行、维护和检修要求。     

输送SO2和SO3的罗茨风机噪声治理

分析了输送SO2和SO3的罗茨风机的噪声特性和控制要求,设计实用的消声器和隔声罩,加大通风换气量,达到了噪声治理的预期目标。     

100t级电炉炉体冶炼噪声控制研究

本文分析了100t级电炉冶炼噪声的产生机理，对噪声控制技术进行了探讨、研究，并提出降噪方案。该项技术在国内同级电炉噪声治理方面很有代表性，具有广泛的推广价值。     

鼓风机噪声的治理

采用隔声、隔振、吸声等措施，治理我厂的两台９－２０ＮＯ６型鼓风机的噪声，使其达到国家规定的《工业企业噪声卫生标准》和《工业企业厂界噪声标准》，保障作业工作及周围居民的身体健康。     

气体生产设备的噪声治理

通过对气体生产设备噪声治理，使厂界噪声能够达到《工业企业厂界噪声标准(GB12348--9)》中Ⅲ类标准，提高了临近居民的生活质量。     

铅熔炼鼓风机房噪声治理

对铅熔炼鼓风机房产生的噪声进行了分析,提出了风机降低噪声综合治理方案并成功实施。     

铅熔炼鼓风机房噪声治理

对铅熔炼鼓风机房产生的噪声进行了分析,提出了风机降低噪声综合治理方案并成功实施。     

大功率风冷线风机噪声综合治理

介绍了高线风冷线风机噪声产生的原因,通过增加专业环保隔声装置,将风机噪声控制在国家标准要求的范围内,实现了打造绿色环保企业的目标。     

论地下矿山噪声污染的危害与防治

噪声污染是地下矿山目前十分严峻的环境问题。为有效进行噪声的防治，首先应该依据所需的数据类型选择进行各种噪声检测工作，噪声防治的方法包括处理噪声源、中断噪声途径或噪音的传播以及隔离劳动者与噪音的接触等。     

Effects of noise on pure-tone thresholds in blackbirds (Agelaius phoeniceus and Molothrus ater) and pigeons (Columba livia).

Blackbirds and pigeons were trained to detect tones in quiet and in broadband noise by using positive-reinforcement techniques. In Experiment 1, thresholds in noise were obtained in blackbirds as a function of both tone frequency and noise intensity for a pulsed noise masker (noise gated on and off with tone). For blackbirds, critical ratios (the ratio of the power of the just-detectable tone in noise to the power of the noise masker) obtained in pulsed noise showed no consistent relation to tone frequency. For pigeons, on the other hand, critical ratios obtained in continuous noise increased by about 3 dB/octave across their range of hearing, being similar to known critical ratio functions for cats and humans. In Experiment 2, critical ratios in blackbirds obtained with both continuous noise and pulsed noise were compared. Blackbird critical ratios were more stable in continuous noise and averaged 4 dB lower than critical ratios in pulsed noise. The blackbird critical ratio function obtained with continuous noise was similar to the known critical ratio function of another avian species, the parakeet. Thus, small birds appear to have atypical critical ratio functions, compared with pigeons and other vertebrates. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Erythroid marrow activity and hemoglobin H levels in hemoglobin H disease

BACKGROUND: Active noise reduction (ANR) is an electronic system that works by continuous sampling of noise inside the earshell of the headset with a small microphone. This signal is inverted in phase through the headset speaker, thus reducing noise levels by destructive interference of the acoustic field. The system provides good low-frequency noise attenuation, but aircrew differ in their subjective opinion of ANR. The present study is an attempt to provide an objective assessment of the effect of ANR on noise levels at the tympanic membrane. METHODS: There were 7 subjects with normal ears who were placed in an environment of recorded noise from a BO-105 helicopter. A microphone probe was inserted to within 5 mm of the tympanic membrane of each subject's right ear. Noise levels in the ear were measured without a headset and with two different ANR headsets. Measurements were performed with and without the ANR system on, and with and without white noise through the headset communication system. The white noise was used to simulate aircraft communication noise. RESULTS: The two headsets tested had differing levels of passive and active attenuation. The ANR system produced a substantial low-frequency attenuation. However, noise levels in the mid frequencies increased somewhat when the ANR system was switched on. This effect was augmented when white noise in the communications system was introduced, particularly for one of the two headsets. Low-frequency noise attenuation of ANR systems is substantial, but an increased mid- and high-frequency noise level caused by the ANR may affect both communication and overall noise levels. Our data provide advice on what factors should be taken into account when ANR is evaluated for use in an aviation operational environment.     

Noise Evaluation for Pavement Maintenance in Metropolitan Highway Bridges

Dynamic response of a bridge under traffic load induces acoustic energy at the bridge surface. The acoustic energy change generates an additional coupled noise component caused by vibration of a bridge deck associated with the pavement conditions and moving velocity of the vehicle. This paper presents a three-dimensional finite-element method developed for the dynamic response and noise propagation model, and analyzes the coupled effect induced by traffic loading based on different pavement conditions. Even though vibration-induced noise at the bridge is below the audible frequency range of 20–20,000?Hz, it amplifies the traffic noise source to the highly annoyed level of noise in the metropolitan area. Among several factors that contribute to the traffic noise, interaction between pavement and vehicle is considered according to the different surface roughness and vehicle velocity. The result shows that poor pavement condition contributes to the increase of traffic noise at a high traveling speed of the vehicle. In the pavement maintenance stage, the coupled effect as an additional noise source should be considered to mitigate the traffic noise for its added value in conjunction with regulation of engine emission noise and construction of a noise barrier.     

钢管厂精整工段的噪声防治

对钢管厂精整工段的噪声产生原因进行了分析 ,在此基础上 ,针对各种噪声产生原因提出了不同的噪声治理措施 ,并对低噪声和无噪声料筐进行了详细论述。     

Neural ensemble coding of target identity in echolocating bats

The Volvo plant at Olofstr?m, Sweden is engaged in the pressing and assembling of sheet-metal components for automobiles. During the past 25 years, determined efforts have been made to introduce less noisy methods of production and to limit the levels of noise emission in three large workshops at the plant. Noise levels were mapped with the aid of stationary noise measurements. The results are expressed in terms of noise emission zones and presented as noise contour maps. The investigations were made on four occasions between 1967 and 1991. Following the comparative area calculations of the noise emission zones, it was deduced that the noise levels had been significantly reduced, despite an increased production. The results show that noise reduction measures applied to the presses. An increase in automation in sheet-metal handling, improved quality in the pressing of components and changes in the range of products have contributed to the reduction of noise levels at the plant.     

Effects of background noise on click-evoked otoacoustic emissions

OBJECTIVE: To investigate the effect of increased levels of background noise on click-evoked otoacoustic emission (CEOAE) recordings and to compare the effectiveness of the default CEOAE program with the QuickScreen CEOAE program in increased levels of noise, using an Otodynamics ILO88 recording device. DESIGN: The right ears of 40 young adult women with normal hearing were assessed using CEOAEs under four different noise conditions and with two different methods of data collection. The noise conditions were in quiet, 50 dB A, 55 dB A, and 60 dB A of white noise. Data were collected at each noise level in the default mode and also using the ILO88 QuickScreen program. RESULTS: There was a significant change in a number of important CEOAE output parameters with increased noise. In the default mode, mean whole wave reproducibility was 89.2% in quiet but declined to 85% with 50 dB A of white noise, 65% at 55 dB A and 20% at 60 dB A. The QuickScreen program proved more robust to the effects of noise than the default. In that mode, mean whole wave reproducibility was 91.7% in quiet, 92.5% with 50 dB A of white noise, 82.5% at 55 dB A and 45% at 60 dB A. CONCLUSIONS: The findings of the study indicate ambient noise levels for accurate CEOAE recording should not exceed 50 to 55 dB A of noise and alternatives to the default program should be considered in non-sound-treated situations.     

Perception of microphone noise in hearing instruments

In a well-designed instrument the noise level is reduced until it is dominated by the front end noise. In a hearing instrument this is the microphone noise. This paper examines the perception of noise in a hearing instrument by both normal-hearing and hearing-impaired listeners. The noise levels are specified as input-referred values in one-third octave bands. Two sets of measurements, the just-objectionable level (JOL) and the just-audible level (JAL), were assessed in third octave bands from 250 to 5000 Hz. The data indicated that the use of a subjectively described acceptability of noise, JOL, is an unreliable measure due to a very large variability across listeners. It is recommended that mean values for the noise threshold level, the JAL, be used as a guide in the optimization of microphone noise design.     

Synergestic effects of noise and aminoglycoside antibiotic (gentamicin) on auditory function in the gerbil

Exposure to excessive noise can cause auditory impairment in people as well as in animals, which can be aggravated by many different ototoxic substances, such as aminoglycosides. In the present study, the gerbil was selected as the experimental animal because the gerbil has low-frequency auditory sensitivity that is similar to human beings. Auditory function in gerbils upon exposure to noise and/or gentamicin was evaluated from non-invasive records of brainstem auditory evoked potentials (BAEPs). Fifty mature male Mongolian gerbils were divided randomly into four groups. The control group was exposed neither to noise nor to gentamicin. The noise group was exposed to 100dBA noise ten hours a day for four weeks. The gentamicin group was treated with one dose of gentamicin, 75 mg/Kg i.m., daily for four weeks. The noise + gentamicin group was exposed concurrently to both noise and gentamicin treatment. BAEPs were recorded from all gerbils 24 hours before any experimental treatment, then every week for eight consecutive weeks. Long-term exposure to noise and/or gentamicin treatment was found to reduce gerbil's body weight. The increase in auditory threshold upon concurrent exposure to both noise and gentamicin treatment (evaluated from BAEPs) exceeded the sum of effects caused by exposure to noise alone and to gentamicin alone. Although differences of peak or interpeak latencies among the four groups were not statistically significant, large standard deviations were noted in the noise+gentamicin group. Thus the apparent threshold shifts in gerbils indicated a major noise and/or gentamicin induced auditory impairment to the cochlea, and the slight latency variations probably suggested a minor injury to the auditory pathways. We emphasize that noise and aminoglycoside antibiotic gentamicin can cause damage to the hearing ability at the frequency range vital to human speech recognition, and their effects are synergetic.     

Contrast detection in noise: a new method for assessing the visual function in cataract

The detectability of a signal decreases in the presence of externally added visual noise. A linear relation exists between the energy of a signal at threshold and the spectral density of the added visual noise. This relation, represented by contrast detection in noise function, allows a given loss in contrast sensitivity (CS) to be attributed to an increase in the internal intrinsic noise and/or a decrease in the detection efficiency of the observer. Intrinsic noise gives a measure of the random background noise within the visual system, whereas detection efficiency is a measure of how effectively the observer utilizes the available stimulus information. Recent work shows that neural dysfunction produces a decrease in the detection efficiency, whereas optical deficits produce a change in the intrinsic noise only. We investigated whether the CS loss in cataract can be attributed to either a change in intrinsic noise, in detection efficiency, or both. Contrast detection in noise functions was measured for 10 uniocular cataract patients. Comparison between the two eyes showed no significant difference in detection efficiency, although the intrinsic noise increased significantly in the cataractous eye. The data suggest that detection efficiency may provide a measure of neural visual function behind a cataract and, conversely, that intrinsic noise provides a measure of the visual effect of the cataract itself. We discuss the implications of intrinsic noise as a measure of cataract for both clinical assessment and research.