我与何泽慧先生交往点滴

<正>1994年我从南京大学博士毕业后来到高能所宇宙线室(现在的粒子天体物理中心),当时我和其他几位同事在二楼的一间大办公室办公,何泽慧先生在天体楼二楼也有一间办公室。我记得无论是在年纪大的老师还是年轻同事的谈话中,大家都以很尊敬的语气提到一个称呼:"何先生"。时间久了,知道这是对我国杰出的女科学家何泽慧院士的尊称。     

《音乐建筑──音乐、声学、建筑》评介

北京市建筑设计研究院项端祈高级工程师撰写的《音乐建筑－音乐、声学、建筑》一书已于１９９９年６月由中国建筑工业出版社出版．这是一本内容丰富的参考书,它提供了大量有关音乐厅、歌剧院、多功能剧院、琴房教室和排练厅、音乐录音室的声学设计资料,并配有精美的插图和照片．建筑师和建筑声学工作者可以从中获得许多有价值的参考,其中包括国外的和国内的,国内的多来自作者多年工程设计的实践经验． 音乐建筑设计涉及音乐、声学和建筑诸多方面,是比较特殊的建筑类型．由于音乐欣赏带有相当大的主观性,故要满足使用者的要求,除了已…     

我的第一篇文章

"少年易老学难成,一寸光阴不可轻"。回想起来,大概每一位新进实验室的博士生都有一种紧迫而又不知所措的感觉。做什么?好像领域里的探索都被前人做完了。怎么做?又有一种"老虎吃天,无处下口"的困惑。每天早上去中科院物理所主楼二楼朝北的一间办公室坐下来,磨蹭会儿,看看书,然后去图书馆里看文献,一上午过去了.     

室内“返潮”的物理原理及其对策

室内“返潮”的物理原理及其对策杨世荣（桂林空军高炮学院５４１００３）刘敏（广西城建学校桂林５４１００３）我国南方的某些地区，每年春夏之交气温回升之际，室内，特别是底层楼室内的地面、家具表面总是湿漉漉的，俗称“返潮”．１“返潮”的物理原因“返潮”不一定...     

八十华诞 硕果累累──祝贺虞福春教授八秩大寿暨执教58周年

八十华诞硕果累累──祝贺虞福春教授八秩大寿暨执教５８周年１９９４年１２月９日上午，北京大学加速器楼洋溢着欢声笑语，校领导与师生共庆实验核物理学家、博士生导师虞福春教授八十华诞暨执教５８周年。虞福春先生１９３６年毕业于北京大学物理系，先后在中央研究院物...     

《音乐建筑──音乐、声学、建筑》评介

北京市建筑设计研究院项端祈高级工程师撰写的 《音乐建筑－音乐、声学、建筑》一书已于1999年 6月由中国建筑工业出版社出版.这是一本内容丰富 的参考书,它提供了大量有关音乐厅、歌剧院、多功 能剧院、琴房教室和排练厅、音乐录音室的声学设计 资料,并配有精美的插图和照片.建筑师和建筑声学 工作者可以从中获得许多有价值的参考,其中包括国 外的和国内的,国内的多来自作者多年工程设计的实 践经验. 音乐建筑设计涉及音乐、声学和建筑诸多方面, 是比较特殊的建筑类型。由于音乐欣赏带有相当大的 主观性,故要满足使用者的要求,除了已掌握的音质 基本物理参量和与之相应的建筑措施外,还需考虑不 少不确定的或未知的因素.但不能因此而认为音乐厅 的音质设计成功与否要"凭运气",是"黑箱作业".     

邓昌黎先生回母校作报告

1984年11月1日,著名美籍高能物理加速器专家、北师大名誉教 授、老校友邓昌黎先生应邀回母校北京师大作了有关质子、反质子碰撞 机及1984年物理诺贝尔奖有关实验的学术报告.应邀出席报告会的 还有北京大学诸圣麟教授、中国音乐学院老志诚教授等. 报告会上,邓先生首先以他长期从事高能物理加速器科技研究事 业的切身体会,总结了物理学和自然科学发展的客观规律,他指出:真 正的物理学是能证实的物理学,物理学的水平应由仪器的水平决定; 高能物理应由加速器的能量级别而定.他还以广义相对论和1984年 诺贝尔物理学奖的实际工作为例进一步阐明了…     

1798年6月：卡文迪许计算地球的重量

1798年6月，伟大的化学家和物理学家亨利·卡文迪许（Henry Cavendish，1731—1810）发表了他著名的地球密度之测定。卡文迪许生性固执、极度害羞且古怪，人们一提到他，就会想起那穿着已过时50年的衣服，总是避开人群，尤其惧怕女性的怪科学家。他都在夜晚外出散步，以避免被邻居撞见，甚至在家中另装一个楼梯，以防上下楼时和仆人相遇。     

校本课程实施案例——有关核电发展的安全与环境问题的专题活动

1案例实施情景情景一:下午第四节课,一楼报告厅不时传出阵阵的掌声,走进一看,高一同学坐满了整个报告厅.这里在听什么报告呢?是什么报告能激起同学们如此高涨的热情?抬头一看,只见报告台上拉了一幅横     

物理之于人生

中国有句哲言：“水平不流，人平不语”，意思是说，水若是平的就不会流动，正如水一样，人若能心态平静，则就不会再多言语。这便是物理与人生哲理绝妙融合的一个很好喻证。水是无形而又有形的物质，古人常用水来比喻人生意境，并孜孜追求之，正所谓“上善若水”，在纷繁的物质世界里能做到这一点确是不易。其实人的性情如能似水，润泽万物而又毫无所求，汇聚江河而又不亢不卑，     

电影音乐录音中的电平控制

声音信号的重要计量值为 VU 值和峰值，它们分别直观反映声音强度及失真情况。为了透彻分析和阐述电影音乐节目制作系统的特性，该文通过实验的方法，测量了大量乐器在典型演奏法下的 VU值和峰值。进而通过实验数据的结果，做出 P/VU概率分布曲线。各音乐信号的 P/VU分布情况决定了系统的电平储备，掌握此结论非常有助于进行电影音乐节目制作过程中的电平控制。     

Monaural room acoustic parameters from music and speech

This paper compares two methods for extracting room acoustic parameters from reverberated speech and music. An approach which uses statistical machine learning, previously developed for speech, is extended to work with music. For speech, reverberation time estimations are within a perceptual difference limen of the true value. For music, virtually all early decay time estimations are within a difference limen of the true value. The estimation accuracy is not good enough in other cases due to differences between the simulated data set used to develop the empirical model and real rooms. The second method carries out a maximum likelihood estimation on decay phases at the end of notes or speech utterances. This paper extends the method to estimate parameters relating to the balance of early and late energies in the impulse response. For reverberation time and speech, the method provides estimations which are within the perceptual difference limen of the true value. For other parameters such as clarity, the estimations are not sufficiently accurate due to the natural reverberance of the excitation signals. Speech is a better test signal than music because of the greater periods of silence in the signal, although music is needed for low frequency measurement.     

Quality and loudness judgments for music subjected to compression limiting

Dynamic-range compression (DRC) is used in the music industry to maximize loudness. The amount of compression applied to commercial recordings has increased over time due to a motivating perspective that louder music is always preferred. In contrast to this viewpoint, artists and consumers have argued that using large amounts of DRC negatively affects the quality of music. However, little research evidence has supported the claims of either position. The present study investigated how DRC affects the perceived loudness and sound quality of recorded music. Rock and classical music samples were peak-normalized and then processed using different amounts of DRC. Normal-hearing listeners rated the processed and unprocessed samples on overall loudness, dynamic range, pleasantness, and preference, using a scaled paired-comparison procedure in two conditions: un-equalized, in which the loudness of the music samples varied, and loudness-equalized, in which loudness differences were minimized. Results indicated that a small amount of compression was preferred in the un-equalized condition, but the highest levels of compression were generally detrimental to quality, whether loudness was equalized or varied. These findings are contrary to the "louder is better" mentality in the music industry and suggest that more conservative use of DRC may be preferred for commercial music.     

Computational models of music perception and cognition II: Domain-specific music processing

In Part I [Purwins H, Herrera P, Grachten M, Hazan A, Marxer R, Serra X. Computational models of music perception and cognition I: The perceptual and cognitive processing chain. Physics of Life Reviews 2008, in press, doi:10.1016/j.plrev.2008.03.004], we addressed the study of cognitive processes that underlie auditory perception of music, and their neural correlates. The aim of the present paper is to summarize empirical findings from music cognition research that are relevant to three prominent music theoretic domains: rhythm, melody, and tonality. Attention is paid to how cognitive processes like category formation, stimulus grouping, and expectation can account for the music theoretic key concepts in these domains, such as beat, meter, voice, consonance. We give an overview of computational models that have been proposed in the literature for a variety of music processing tasks related to rhythm, melody, and tonality. Although the present state-of-the-art in computational modeling of music cognition definitely provides valuable resources for testing specific hypotheses and theories, we observe the need for models that integrate the various aspects of music perception and cognition into a single framework. Such models should be able to account for aspects that until now have only rarely been addressed in computational models of music cognition, like the active nature of perception and the development of cognitive capacities from infancy to adulthood.     

Complex network structure of musical compositions: Algorithmic generation of appealing music

In this paper we construct networks for music and attempt to compose music artificially. Networks are constructed with nodes and edges corresponding to musical notes and their co-occurring connections. We analyze classical music from Bach, Mozart, Chopin, as well as other types of music such as Chinese pop music. We observe remarkably similar properties in all networks constructed from the selected compositions. We conjecture that preserving the universal network properties is a necessary step in artificial composition of music. Power-law exponents of node degree, node strength and/or edge weight distributions, mean degrees, clustering coefficients, mean geodesic distances, etc. are reported. With the network constructed, music can be composed artificially using a controlled random walk algorithm, which begins with a randomly chosen note and selects the subsequent notes according to a simple set of rules that compares the weights of the edges, weights of the nodes, and/or the degrees of nodes. By generating a large number of compositions, we find that this algorithm generates music which has the necessary qualities to be subjectively judged as appealing.     

Acoustic analysis and mood classification of pain-relieving music

Listening to preferred music (that which is chosen by the participant) has been shown to be effective in mitigating the effects of pain when compared to silence and a variety of distraction techniques. The wide range of genre, tempo, and structure in music chosen by participants in studies utilizing experimentally induced pain has led to the assertion that structure does not play a significant role, rather listening to preferred music renders the music "functionally equivalent" as regards its effect upon pain perception. This study addresses this assumption and performs detailed analysis of a selection of music chosen from three pain studies. Music analysis showed significant correlation between timbral and tonal aspects of music and measurements of pain tolerance and perceived pain intensity. Mood classification was performed using a hierarchical Gaussian Mixture Model, which indicated the majority of the chosen music expressed contentment. The results suggest that in addition to personal preference, associations with music and the listening context, emotion expressed by music, as defined by its acoustical content, is important to enhancing emotional engagement with music and therefore enhances the level of pain reduction and tolerance.     

Short sound decay of ancient Chinese music bells

Ancient Chinese music bells, which have oval-like cross sections, possess the unique feature of a short sound-decay time that is especially suitable for music with fast tempo. Although recorded in the literature nearly 1000 years ago, this feature has never been truly understood. Recent damping measurement of oval pipes with different axial ratios suggested a challenging task for acousticians as the increase of the modal damping with the pipe's axial ratio is significant only when the pipe response is measured in air but not in vacuum. In this paper, the decrease of sound-decay time of oval pipes with the increased cross-section ovality is investigated. This is the first time that such short sound-decay feature is explained in terms of the rich sound radiation characteristics of the symmetric modes of music bells and the oval pipes. Finite element and boundary element methods are employed to explain how axial ratio significantly affects the normal velocity distribution, radiation efficiency, and directivity of acoustic modes.     

Phase synchronization of instrumental music signals

Signal analysis is one of the finest scientific techniques in communication theory. Some quantitative and qualitative measures describe the pattern of a music signal, vary from one to another. Same musical recital, when played by different instrumentalists, generates different types of music patterns. The reason behind various patterns is the psycho-acoustic measures – Dynamics, Timber, Tonality and Rhythm, varies in each time. However, the psycho-acoustic study of the music signals does not reveal any idea about the similarity between the signals. For such cases, study of synchronization of long-term nonlinear dynamics may provide effective results. In this context, phase synchronization (PS) is one of the measures to show synchronization between two non-identical signals. In fact, it is very critical to investigate any other kind of synchronization for experimental condition, because those are completely non identical signals. Also, there exists equivalence between the phases and the distances of the diagonal line in Recurrence plot (RP) of the signals, which is quantifiable by the recurrence quantification measure τ-recurrence rate. This paper considers two nonlinear music signals based on same raga played by two eminent sitar instrumentalists as two non-identical sources. The psycho-acoustic study shows how the Dynamics, Timber, Tonality and Rhythm vary for the two music signals. Then, long term analysis in the form of phase space reconstruction is performed, which reveals the chaotic phase spaces for both the signals. From the RP of both the phase spaces, τ-recurrence rate is calculated. Finally by the correlation of normalized tau-recurrence rate of their 3D phase spaces and the PS of the two music signals has been established. The numerical results well support the analysis.     

Correlations in a Mozart's music score (K-73x) with palindromic and upside-down structure

In this work, we study long-range correlations in a “Scherzo-Duetto di Mozart” score (K-73x) for two violins. This is a fascinating piece, as the second violin part is upside down on the same sheet below the first violin, and some parts are like a palindrome. Given such ingenious structure, it is expected the existence of long-range correlations in the score structure. In order to quantify long-range correlations, we considered the music score as a sequence of integer numbers, each of them corresponding to last common denominator units of note. By using detrended fluctuation analysis (DFA), correlations are quantified by means of the scaling exponent that reflects the type of correlations for a given distance between neighbors note. The following conclusions can be drawn from the analysis: (a) For about 10-25 neighbor note distances, correlations are similar to 1/f-noise. This is an interesting finding since it has been shown that pleasant sounds for humans display a behavior similar to 1/f noise. (b) As the neighbor note distance increases, the long-range correlations decays continuously. For some score sections, the music score behaves like non-correlated (i.e., purely random) noise. Summing up, the results show that the studied Mozart's score contains a certain degree of correlation for relatively small note distances, and becomes close to non-correlated behavior for long note distances. We considered also the sequence constructed by considering the distance between the simultaneously played notes of the two violins. Interestingly, for relatively small neighbor note distances, a scaling behavior similar to that found for individual violins is also displayed. In some sense, this is an expression of the specific structure (palindromes plus upside down construction) used by Mozart in the composition of this music score. Although we focused on a particular high-art music score, our results suggest that modern methods borrowed from statistical physics can be useful for the systematic study of music composition techniques.     

The effect of loudness on the reverberance of music: reverberance prediction using loudness models

This study examines the auditory attribute that describes the perceived amount of reverberation, known as "reverberance." Listening experiments were performed using two signals commonly heard in auditoria: excerpts of orchestral music and western classical singing. Listeners adjusted the decay rate of room impulse responses prior to convolution with these signals, so as to match the reverberance of each stimulus to that of a reference stimulus. The analysis examines the hypothesis that reverberance is related to the loudness decay rate of the underlying room impulse response. This hypothesis is tested using computational models of time varying or dynamic loudness, from which parameters analogous to conventional reverberation parameters (early decay time and reverberation time) are derived. The results show that listening level significantly affects reverberance, and that the loudness-based parameters outperform related conventional parameters. Results support the proposed relationship between reverberance and the computationally predicted loudness decay function of sound in rooms.