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二、“现代”大气声学1.重力和科里奥利(Coriolis)力对声传播的影响(1)声重力波和内重力波重力场对寻常声波(包括可听声和频率较高的次声,当然更包括超声,但因后者在空气中衰减太快,不能成为大气声学研究对象)的影响完全可以忽略,但当频率低到一定程度时就必须考虑这种影响了.声波中的运动加速度与频率的平方成正比,对于寻常声波,这一加速度的数值远比重力加速度g大.但当频率的数量级约为g/c时,这两个加速度就属于同数量级的了.实际上,因重力作用,大气密度随高度增加而减小.例如,对于频率为g/c0.029Hz的声波,其波… 相似文献
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本文简述环境声学的发展过程以及在厅堂音质、环境噪声和噪声控制方面的新世纪展望。 相似文献
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The acoustic and perceptive characteristics of discourse units, including clauses, simple sentences, compound sentences and paragraphs, were studied. The acoustic characteristics were based on the analysis of a speech corpus consisted of ten monologues. The Perceived Boundary Strength (PBS) of the monologues was labeled on a five-point scale by 25 participants. The main results are as follows: (1) There is a significant difference in the PBS of clauses (corresponding to intonational phrase), sentences (including simple sentences and compound sentences) and paragraphs. But the PBS of simple sentences and compound sentences is the same, and the pitch reset and pause are also not significantly different between these two kinds of boundaries. (2) The pitch-based cue used to distinguish clauses, sentences and paragraphs appears to be the difference between pre- and post-boundary syllables, but not simply the pitch value of either syllable alone. (3) Declination mainly occurs within intonational phrases, whereas there is no consistent global declination in sentences or in paragraphs. (4) Pauses are longer and more varied at the boundary of larger discourse units. Moreover, there is a significant positive correlation between pause duration and degree of pitch reset at clause boundaries, but not at sentence or paragraph boundaries. 相似文献
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赵恒元教授因病于1994年2月11日晚12时不幸逝世,享年79岁.在赵先生逝世周年之际,我们作为他的同行和挚友,也代表所有他的同事和学生,谨写这篇短文,以表达对他的怀念和追思.赵先生1915年2月生于山西省寿阳县.1938年毕业于北京师范大学物理系.随后五十多年从事高等学校的教学、科研和管理工作.教学上,曾先后担任川北大学物理系主任、西安师院和陕西师大物理系主任、陕西师大副校长等等多项职务.先后讲授电动力学、近代物理、声学、超声学等课程.1982年以来培养出30多名声学专业的硕士研究生.1988年被评为国家级劳动模范.赵恒元… 相似文献
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《声学学报:英文版》2013,(4):454-457
43.05. History; 43.10. General; 43.15. Standards; 43.20. General linear acoustics; 43.25. Nonlinear acoustics; 43.28. Aeroacoustics and atmospheric sound; 43.30. Underwater sound; 43.35. Ultrasonics, quantum acoustics, and physical effects of sound; 43.38. Transdnction, acoustical devices for the gen- eration and reproduction of sound; 43.40. Structural acoustics and vibration; 43.50. Noise: its effects and control; 相似文献