共查询到20条相似文献,搜索用时 15 毫秒
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本文简要介绍了活塞发声器的工作原理及其声压级的测量原理,着重分析了未知耦合腔体积活塞发声器的有效体积与声压级的测量方法。 相似文献
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椰胡是具有地方特色的拉弦乐器之一,多用于演奏广东音乐和广东戏曲、曲艺的伴奏。但对其发声强度一直未进行过科学的测试。本文介绍在华南理工大学半消声室内参照ISO(GB)标准对椰胡声功率级的测量工作。由两位资深乐师分别用两把椰胡在pp,mp,f和ff力度下演奏单音、音阶和乐曲,对每一把椰胡的每一测试内容,由十通道测试设备同步测试中心频率为100~10000 Hz的1/3倍频带声压级谱,通过计算获得每把椰胡在演奏每项内容时的声功率级和动态范围。通过对两把椰胡的测试结果进行平均,获得该乐器在演奏上述内容时的典型声功率级数值及频谱。文中并将半消声室内的测试结果与混响室内的测试结果相对比,探讨测试环境对测试结果的影响。民族乐器发声强度及其频谱特性的获得是开展民族音乐厅堂音质研究的基础。 相似文献
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The number of helicopter operations has rapidly increased during the last 20 years in Japan. Helicopter noise sounds different from other aircraft; the waveform of the sound pressure is impulsive and the signal duration is relatively long. The Environmental Agency of Japan implemented new guidelines for evaluating noise exposure around small airports, including heliports, in 1990. This study was executed in connection with the development of provisional guidelines. Psychoacoustic experiments were carried out to identify an evaluation index for helicopter noise. In order to examine the effect of duration independently, we not only used original sound recordings, but also synthesized sound signals. The durations of these sound signals were time compressed or expanded without degrading the quality of the original sound recording. The test results show that the effect of duration is significant, and that the A-weighted sound exposure level is a better index than the maximum A-weighted sound pressure level for the evaluation of helicopter noise. 相似文献
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The fundamental frequency (F0) for the habitual pitch (F0HAB), F0 for the lowest physiological tone (F0L), F0 for the highest physiological tone (F0H), F0 range of phonation (F0 Rg), sound pressure level (SPL) for habitual loudness (SPLHAB), SPL for the softest tone (SPLS), SPL for the loudest tone (SPLL), and SPL range of phonation (SPL Rg) were measured in 40 normal adult subjects and 1,563 voice patients with varying diseases. F0H, F0 Rg, SPLL, and SPL Rg were decreased in many disease groups. F0HAB and F0L varied. SPLHAB and SPLS were increased in some disease groups. F0-related parameters reflected effects of treatments in the cases with polyp, Reinke's edema, epithelial hyperplasia, carcinoma, and paralysis. Effects of treatments were manifested in SPL-related parameters in the cases with nodule, polyp, carcinoma, and paralysis. 相似文献
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针对现有方法对材料吸声系数进行现场测量时存在低频测量误差大的问题,本文提出了一种利用扬声器线阵列对材料吸声系数进行现场测量的新方法。该方法使用基于能量比值约束的最小二乘法在待测材料表面进行平面波声场重建并结合双传声器传递函数法对材料的吸声系数进行测量。数值仿真表明在100~1600 Hz频率范围内,新方法在未加约束时能够对材料的吸声系数进行准确测量。在半消声室中利用新方法测量了三聚氰胺泡沫的吸声系数,分析了能量比值约束值对测量结果的影响,并和阻抗管以及其它两种现场测量方法的测量结果进行了对比。结果表明该方法能够对吸声材料在160~1600 Hz频段内的吸声系数进行准确测量,并且相较于现存的现场测量方法,新方法具有更低的测量频率下限。 相似文献
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This paper presents a study on the perception of soundscapes in train stations. The two issues addressed by this study are (1) to show that people’s knowledge about the space typology that makes up a train station is also based on sound information, and (2) to show that this information is involved in the recognition of the type of space. This study is composed of two stages. In the first stage, two auditory experiments are performed on 66 soundscape samples recorded under natural conditions: (1) free categorization with verbalization and (2) forced-choice recognition. The statistical and lexical analysis of the first experiment reveals three main types of acoustical information: sound sources, human activities, and room effects. The results of the second experiment show that people were able to recognize the type of space (platform, hall, etc.) just by listening to its soundscape. Comparison between Experiments 1 and 2 reveals the auditory similarities of the soundscapes that were recognized as belonging to the same category. In the second step, an in situ questionnaire survey was carried out and confirms the laboratory results. Indeed, when travelers are asked to describe the soundscape of the space in which they are situated, they use the same kind of auditory similarities as those found in the experiments. 相似文献
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US National Parks and management of park soundscapes: A review 总被引:1,自引:0,他引:1
Nicholas P. Miller 《Applied Acoustics》2008,69(2):77-92
For more than 17 years the US National Park Service has been developing the methods, processes and skills required to effectively manage the soundscapes of the National Parks. The author and his company have had the honor of providing technical acoustics related assistance throughout much of this period. This article presents his reflections on the process, its technical and political complexities, and provides what are hoped to be useful syntheses derived both from his experiences and from past and recent discussions with many of the participants. Specifically, the article describes the fundamental questions that need to be answered for management of natural soundscapes, the types of noise issues that arise in parks, the need for quantitative data, approaches to identifying, measuring and collecting those data, and a suggested approach for developing criteria designed to effectively manage sounds in natural areas. 相似文献
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A fast automatic calibration system for a sound level meter in an anechoic environment has been developed. The precise and fast generation of the constant frequency-independent acoustic pressure field and reduction of digital voltmeter readout to sound pressure level were achieved by a newly designed software algorithm, assuming the system linearity. The performance test justified the assumed linearity, and showed that the searching speed was sufficiently fast within the small error limit. 相似文献
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J.W. Trevathan 《Applied Acoustics》2008,69(2):127-131
A study of the airborne sound transmission in a multi-tenanted building has shown that elements of the building which are nominally identical do not have the same acoustic performance. It was seen that some of this variation in performance could be attributed to visually-observable differences in the constructions. Some of the variation could not be explained however, and it was concluded that this variation was due to workmanship. The level of this variation was seen to be approximately 1 dB for a light steel framed construction. This variation is considerably less than that measured previously for a monolithic construction. 相似文献
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Procedures for the field measurement of airborne sound insulation between rooms with diffuse fields are described in International Standard ISO 140-4. However, many dwellings contain rooms with volumes less than 50 m3, where low frequency measurements are less reliable; hence there is a need for a measurement procedure to improve the reliability of field measurements in rooms with non-diffuse fields. Procedures are proposed for sound pressure level and reverberation time measurements for the 50, 63 and 80 Hz third octave bands. The sound pressure level measurement combines corner microphone positions with positions in the central region of each room. This provides a good estimate of the room average sound pressure level with significantly improved repeatability. 相似文献
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Maximum sound pressure levels are commonly used for environmental noise and building acoustics measurements. This paper investigates the signal processing errors due to Fast or Slow time-weighting detectors when combined with octave band filters, one-third octave band filters or an A-weighting filter. For 6th order Butterworth CPB filters the inherent time delay caused by the phase response of filters is quantified using three different approaches to establish the following rules-of-thumb: (1) time-to-gradient/amplitude matching occurs when Bt ≈ 1, (2) time-to-peak matching occurs when Bt ≈ 2 and (3) time-to-settle matching occurs when Bt ≈ 4 for octave band filters, and when Bt ≈ 3 for one-third octave band filters. Four different commercially-available sound level meters are used to quantify the variation in measured maximum levels using tone bursts, half-sine pulses, ramped noise and recorded transients. Tone bursts indicate that Slow time-weighting is inappropriate for maximum level measurements due to the large bias error. The results also show that there is more variation between sound level meters when considering Fast time-weighted maximum levels in octave bands or one-third octave bands than with A-weighted levels. To reduce the variation between measurements with different sound level meters, it is proposed that limits could be prescribed on the phase response for CPB filters and A-weighting filters. 相似文献
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Dae Seung Cho 《Applied Acoustics》2008,69(3):185-195
This paper presents a new and efficient method to determine sound power levels (PWLs). PWLs, generally used for modeling outdoor sound simulations, are obtained from sounds that are emitted by various types of vehicles and cause road traffic noise. Other models, such as HARMONOISE and the ASJ Model, are also based on PWLs. However, a more efficient method is required for determining PWLs from sound pressure levels (SPLs) that typically are measured by field testing and evaluating the influence of different vehicles and road surfaces. The statistical pass-by (SPB) of ISO 11819-1 is used for SPL measurements; however, numerous SPBs must be carried out to reduce measurement uncertainty as well as to satisfy requirements related to meteorological conditions and background noise. In order to alleviate this problem and to make the determination of PWLS more efficient, a testing approach is presented that uses both the novel close proximity (NCPX) method and the pass-by method to determine PWLs. 相似文献
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Previous studies have shown that auditory cues contribute to the identification of several components of a public space such as the volume, but also the type of activity to which the space is dedicated. This paper demonstrates that solutions to improve way-finding in a public place can be based on providing additional auditory information. A methodical approach in three phases is proposed and applied in the case of a train station. First, problems encountered by travellers in a train station are identified by way of an ergonomic study under real conditions with recruited travellers. The results reveal three kinds of problems: orientation errors, lack of confirmation of direction, and lack of information about the remaining distance to be covered. In the second phase, functional and environmental specifications were developed in order to create sound signals for each identified problem. A sound designer proposed several non-speech sound signals based on two schemas: a pair of sounds for the orientation and confirmation functions, and a timeline sequence for the remaining distance. Finally, in the third phase, the sound signals were installed in the train station using an experimental broadcasting system and were evaluated in a second ergonomic study using the same method. The results show that the number of orientation errors decreased and that participants felt more confident during their walk. Sound signals for the orientation and confirmation functions were understood and used by the participants. However, the timeline sequence signalling remaining distance was not understood. 相似文献
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Since the classical room acoustics can not be used for long enclosures due to the inhomogeneous sound field, much work has been carried out recently to investigate the sound propagation in long enclosures, which are helpful to the acoustic design of practical long enclosures, such as the high-speed railway tunnels. However, most of these works focuses on the straight long enclosures without branches or with one branch. In this paper, the effects of the multiple branches on sound propagation of long enclosures are studied. The sound pressure level (SPL) attenuation, early decay time (EDT), and reverberation time (T30) of long enclosures with multiple branches have been investigated by physical scale models based acoustic experiments. Several interesting results have been obtained concerning the sound propagation of long enclosures with multiple branches. It shows that the sound field of long enclosures with multiple branches is more complex and inhomogeneous than that of the long enclosures without branches or with one branch. 相似文献