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相消干涉(destructive interference)，和相长干涉(constructive interference)是物理学术语。
我认为还有一个元素是街头篮球
MySQL (beta) at CHEARSdotinfo.co.uk -> The Sampling Theorem As long as there are at least two samples per period of the original waveform, we can assume that the resynthesized waveform will have the same frequency. But when there are fewer than two samples per period, the frequency (and perhaps the timbre) of the original signal is lost. The sampling theorem describes the relationship between the sampling rate and the bandwidth of the signal being transmitted. there are at least two samples per period of the original waveform. To give a concrete example, suppose we introduce an analog signal at 26 KHz into an analog-to-digital converter operating at 50 KHz. The converter reads it as a tone at 24 KHz, since 50 -26 = 24 KHz. The essential point of the sampling theorem can be stated precisely as follows: In order to be able to reconstruct a signal, the sampling frequency must be at least twice the frequency of the signal being sampled. The highest frequency that can be produced in a digital audio system is called the Nyquist frequency. In musical applications, the Nyquist frequency is usually in the upper range of human hearing, above 20 KHz. Then the sampling frequency can be specified as being at least twice as much, or above 40 KHz. --- Ideal Sampling Frequency Many people hear information (referred to as "air") in the region around the 20 KHz "limit" on human hearing (Neve 1992). Indeed, Rudolf Koenig, whose precise measurements set international standards for acoustics, observed at age 41 that his own hearing extended to 23 KHz (Koenig 1899). It seems strange that a new digital compact disc should have less bandwidth than a phonograph record made in the 1960s, or a new digital audio recorder should have less bandwidth than a twenty-year old analog tape recorder. Many analog systems can reproduce frequencies beyond 25 KHz. Scientific experiments confirm the effects of sounds above 22 KHz from both physiological and subjective viewpoints (Oohashi et al. 1991; Oohashi et al. 1993). In sound synthesis applications, the lack of "frequency headroom" in standard sampling rates of 44.1 and 48 KHz causes serious problems. It requires that synthesis algorithms generate nothing other than sine waves above 11 KHz (44.1 KHz sampling rate) or 12 KHz (48 KHz sampling rate), or foldover will occur. This is because any high-frequency component with partials beyond the fundamental has a frequency that exceeds the Nyquist rate. The third harmonic of a tone at 12.5 KHz, for example, is 37.5 KHz, which in a system running at 44.1 KHz sampling rate will reflect down to an audible 6600 Hz tone. In sampling and pitch-shifting applications, the lack of frequency headroom requires that samples be lowpass filtered before they are pitch-shifted upward. The trouble these limits impose is inconvenient. --- Antialiasing and Anti-imaging Filters In order to make sure that a digital sound system works properly, two important filters are included. One filter is placed before the ADC, to make sure that nothing (or as little as possible) in the input signal occurs at a frequency higher than half of the sampling frequency. Logically enough, such a filter is called an antialiasing filter. The other filter is placed after the DAC. Its main function is to change the samples stored digitally into a smooth, continuous representation of the signal.
In this morning，I got my first acoustic music course at Oregon of university which is the most beautiful college I never seen!Also, the great atmosphere of study and cutting edge school establishment are extremely impressed. the course is as amazing as this university,although just began the course , I already love it. Professor Stolet showed us the studio where we are going to spend most of our time in it in two weeks. Jeffrey taught us electroacoustic music uses modern technology to find sounds to make music through recording sample. Recording sample can be very critical, it can directly affect the quality of your music. We recorded few neutral sounds such as coin rolling, human voices and glass, etc. Then we used Peak pro to edit samples that we recorded. The process of editing samples must be very careful. If you don't, you won't have a sound as great as it should be. I opened my mind after first class and it gave me a lot of new ideas, but there is a kind of ambiguity on the contents of human voice part in the recording. Since Chinese is a kind of language with 5 tones and it sounds very melodic, we have to choose it very carefully to be the recording sample in our piece. Wang Chi recited a poetry that was talking about a men expressed his respect and love to his mother, but i think it is not all right that we ignore the language meaning and just focus the tone of the language. We should have some purposes to use this sample of the poetry that has the same emotion from the works. I know Prof. Stolet is an enthusiasm with Chinese, but i hope he could learn more about Chinese with deeper understanding of the culture. Otherwise, it looks like a culture abusement :) 这个早上，我在俄勒冈大学参加电子音乐的课程，这个学校是我见过风光最美的大学。并且这个学校良好的学习氛围和先进的设备让我印象深刻。这个课程像大学一样精彩，虽然课程刚开始，但是我已经非常感兴趣。 stolet教授，给我们展示了他的工作室，我们将会在未来的两周在这个工作室工作。stolet教我们用现代科技去寻找自己想要的声音去制作音乐，和如何去录制声音。声音的录制是非常严格的，它直接影响音乐的质量。我们录制了几个自然界的声音，像滚动钱币的声音，人声，玻璃的声音等等。然后我们用peak pro 这个软件去编辑我们已经录制的采样，编辑的过程一定要非常的细心，如果不的话，你不会拥有一个足够好的采样声音。 我通过今天的课程开阔了眼界，让我有了很多新的想法，但是在录制人声部分我对人声的内容有一些歧义。我们之所以选择用中国的语言来采样，因为中国话是带有声调的语言，更加旋律化。一位女生朗读了一首游子吟，这首诗讲的是诗人对母爱的感激以及对母亲深深的爱与尊敬。我认为如果只关注这首诗的“旋律”部分而忽略了诗的内容的话是得不偿失的，应该有目的的用这个诗的素材来做符合音乐情感的作品。我知道stolet教授一定非常热爱中文，但是我希望他多多学习中文，更深入的了解中国的文化。
Luigi Nono was an Italian avant-garde composer of classical music and remains one of the most prominent composers of 20 century (wikipedia) Nono’s music is very quiet and simple; however this idea is throughout his music. Expect “II canto sospeso”, I have never known about Nono could compose electroacoustic music until I had this lesson today. His piece, For Solo Tuba and Live electronics (1987), is very unique .I'm not sure it is the first piece that uses live instrument an electroacoustic music, but I certainly believe it influences electroacoustic music at present. Science and technology of today is better than past, I have to say although this piece used extremely limited method, such as reverb and delay, it did an amazing things! In this piece, chapter one is my favorite. He used a few rows and each row has a different performance practice, for instance when you play "row number one", you need to play the note and sing at same time; when you play "row number two", you need to play a note just get the valve half pressed and so on. There are seven of rows in total. In summary, chapter one is a puzzle for me, which was why I like it so much. If I'm a tube soloist, when I play this chapter, it is more like an adventure I have never had before. Seven rows use seven different colors and it does not mean "row number one" has to be played at the beginning. Before he writes his music, he will discuss with someone. It is just like a brain storm. Nono invented a lot new performance practice, so it is also a challenge to the player. There is an interesting thing in the score, you can see a long note its dynamics from "pppp" to "ffff". It is kind of extreme use of dynamic and it is very hard to play. I think it's a dynamic envelope as same as "ADSR"(attack, decay, sustain, release).
Alvin Lucier is a batman. Why I say it? In his music, he is always fightting with "feedback". In 2007 Beijing modern music festival, Central Conservatory of Music invited Alvin Lucier to give a lecture. Alvin Lucier marked a new epoch in body language of performing arts. He uses dynamic-media convey visual-imagery in sound and makes people through his music evoke a natural view in brain. Some other people already talk a lot about his piece, I Am Sitting in a Room, so I will talk about his breakthrough composition, Music for Solo Performer for Enormously Amplified Brain Waves and Percussion. It was the first piece to feature sounds generated by brain waves in live performance and the biological stimuli played an increasing role in Lucier's subsequent work, most notably through his notation of performers' physical movements. Everyone's body have magnetic field when people think, the magnetic field will change, became a biology electric current through magnetic field and we call that brain wave. Animals might have the same alpha wave came from human being. Is it possible we could have a real “three blind mice” ensemble? I never thought about someone could use his brain wave to compose a piece. It reminds me a completely difference thing: Schumann Resonance. It is a set of spectrum peaks in the extremely low frequency (ELF) portion of the Earth's electromagnetic field spectrum. Schumann resonances are global electromagnetic resonances, excited by lightning discharges in the cavity formed by the Earth's surface and the ionosphere. I am wondering if we also can use this theory to compose a piece?
I would like to quote two extracts from John Cage, he says: “silence is not the same as no sound” and “I compose music to hear things I have not heard before”. Those words illustrate an attitude that John Cage looks upon music. It's extraordinarily important and this notion has a significant influence over John Cage. It is not merely a good chance to know John Cage, but also a good chance of music! John age developed a notational system called "time brackets." Each performer performs his music in a strict order, but the actual start-and stop-times for each event vary. While the time bracket system ensured that the total time for a performance would always remain the same, it allowed flexibility to the performers in the spirit of Cage's indeterminate aesthetic. I know about "time brackets from the lecture and I would like to use it in my own piece. The "time brackets" broke an pattern of traditional music notation, for example, you can play a note at 0'00" to 0'45"or you can play it at 0'30" to 1'15", which means that perform is kind of freedom that you want to follow your heart. There is a lot space for performer to play music belonging to him. After the lecture, I have done some research. I found he uses a concept of “I Ching” to write a piece called 4'33". The three movements of which are performed without a single note being played. The content of the composition is meant to be perceived as the sounds of the environment that the listeners hear while it is performed, rather than merely as four minutes and thirty three seconds of silence, and the piece became one of the most controversial compositions of the twentieth century. Another famous creation of Cage's is the Prepared Piano (a piano with its sound altered by placing various objects in the strings), for which he wrote numerous dance-related works and a few concert pieces, the best known of which is Sonatas and Interludes.
这次的MAX/MSP工作坊是在9月初开始的，我很兴奋，因为我从来没有系统的学习过MAX，只是私底下看看软件自带的教程。虽然已经有了一个初步的了解，但具体内容还不是很清楚。这次的工作坊只有5天，我觉得算是速成吧。但好在就是MAX部分和MSP部分并不是分隔开来讲的。记得我自己看教程的时候，先看的MAX部分，看了很多章节之后还是没听见任何声音，那时候对这个软件已经失去兴趣了。所以我觉得这次的教学在这点安排的是非常好的。每天的上午我们会学一些新的物件和怎么使用，下午就相对自由一些，把自己的想法付诸实践编写成PATCH，遇到什么困难，就请教老师。但，这次的工作坊也有很多需要改进的地方，5天的课程实在太短了，刚刚对MAX有一些感觉，进入了一些状态时就结束课程了，觉得很遗憾。
