Progress made over the past decade in understanding the mechanisms of sound production in music wind instruments is reviewed. The behavior of air columns, horns, and fingerholes is now fairly well understood, and most recent interest centers on details of the sound generator — the reed in woodwinds, the lips in brass instruments, and the air jet in flute-family instruments. Not only do these generators produce the sound, but they are also largely responsible, through their nonlinearity, for controlling the harmonic content and thus the musical timbre of the instrument, the one major exception being in loud playing on brass instruments where propagation nonlinearities in the air column are also important. Despite considerable progress, there remain important and interesting questions to be answered.
Recent research on the acoustics of percussion instruments has focussed on observing their modes of vibration and understanding how they radiate sound. Holographic interferometry, on account of its high resolution, is an especially useful method for modal analysis on a wide variety of percussion instruments. Several new percussion instruments as well as studies on some very ancient ones are described. New instruments include tuned wind chimes, Caribbean steelpans, major-third bells, bass handbells, Choirchimes, and glass instruments.
This paper presents several methods for the alignment of a music score (given in MIDI form) to a human performance of the same musical piece. Two distinct cases are considered: first, MIDI-to-MIDI alignment, where rhythm changes, note time shifts, and player errors are handled by a Dynamic-Programming (DP) algorithm. Next, a method for MIDI-to-audio alignment is presented, incorporating spectral data into the DP method. Experiments on a music database showed the effectiveness of the alignment algorithms. For cases where the alignment process gets trapped in a wrong local minimum, an efficient manual bootstrapping method was developed and shown to lead to the selection of the correct alignment.
The sawari is an instrumental mechanism of a certain class of stringed instruments so that the string touches to it repeatedly when vibrating. The Chikuzen biwa is one of Japanese plucked stringed instruments; it is equipped with a sawari which is a narrow strip of surface on the top of shirabeguchi (the nut). It is known that only a minute change in the shape of this surface results in a large difference in the quality of the resulting “sawari” tone. This paper studies the sawari tone under different grades, or strengths, of the sawari created by shaving the top surface of shirabeguchi differently with masterly craftsmanship, together with one without sawari (no shaving at all), using an excellent Chikuzen 5-stringed biwa, to compare quantitatively the effect of the degree of shaving on the resulting sound. The analysis shows the temporal development of the amplitudes of up to 24th partials for open strings under each of the above-mentioned sawari conditions. The sawari effect appears in two aspects: (1) to intensify the partials of 6th to 20th and up, and (2) to elongate their durations.
In this paper, we introduce a new percussion instrument, “hokyo,” made of a particular stone, “Sanukite,” and study its vibrational properties. The hokyo has a unique and somewhat complicated structure. Vibrational modes of the hokyo were analyzed by the finite element method, and their existence was verified by fast Fourier analysis of its tone and experimental modal analysis. The vibrational modes of the hokyo are principally determined by the rather simple behavior of the centered inner rod with a quasi-fixed end and a free end. The term “quasi-fixed end” means that the inner rod is not fixed exactly but only approximately at the base. The important modes of the inner rod are the fundamental bending mode, the torsional mode, and the longitudinal mode. The out of phase motion between the inner rod and the outer frame of a hokyo, coupled to each other by the base, produces a quasi-fixed boundary condition at the base. The quasi-fixed end gives a practical advantage to the hokyo in that it can shorten the length of the instrument very much compared to the instrument with free ends.
The aim of this study was to investigate the implicit memory for short rhythmic tone sequences from the viewpoint of cognitive psychology. The nature of memory representation for rhythmic tone sequences was researched by using priming and recognition tasks. At first, participants were asked to rate “coherence" of a rhythmic tone sequence. Then, half of the participants performed the priming task: studied and nonstudied tone sequences, both of which were of the same intensity, were presented in succession at intervals of 2 s, and participants were asked to judge which of the two tone sequences sounded “louder." The rest of the participants performed a yes/no recognition test. The following results were obtained: 1) studied tone sequences were judged to be louder than non-studied ones in both pitch-changed and not changed conditions, 2) the priming effect decreased as the pitch changed, 3) the direction of pitch change did not influence the priming, 4) priming and recognition performance were independent of one another. These results lead to the conclusion that an implicit memory for musical rhythm exists, and pitch information is coded into the representation underlying perceptual priming of rhythmic tone sequences.
We studied the relationship between amplitude and frequency fluctuations of harmonics and the perceived quality of flute tones with vibrato. To investigate the effects of minute and irregular fluctuations on timbre, a real flute tone and synthesized flute tones whose relative amplitude levels of harmonics and extent of vibrato were equal to those of the real tone, were used for the subjective experiments. Listener’s preference for flute tones was found to be affected by the degree of intensification or attenuation of the frequency and amplitude fluctuations above 13 Hz. Also, we investigated the physical properties of the fluctuations that affect perceived quality of flute tones, by synthesizing fluctuation waves of harmonics. The results of evaluation by test subjects show that there was no perceived difference in quality between the original tone and synthesized tones with fluctuations that were synthesized by randomization of the phase spectra of the original fluctuations. In contrast, synthesized tones with fluctuations that were synthesized from filtered noise were perceived to be significantly inferior to the original tone. These results suggest that spectral variation of fluctuation waves which is at higher frequency and lower amplitude than spectral variation of vibrato influences perceived quality.
The relationship between off-scale perception and the perception of simultaneity of two pure tones presented almost simultaneously is studied. The characteristics of off-scale perception and the perception of simultaneity were measured as a function of the onset asynchrony between the two quasi-simultaneous tones. The experimental results revealed that off-scale perception is affected by the onset asynchrony of about 30 ms even when listeners cannot detect the asynchrony. It is reported that there exists an onset asynchrony of about 30–40 ms among sounds generated by natural musical instruments in an ensemble. This study is important for revealing the auditory characteristics used to judge the appropriateness of the tone height of sounds in a musical performance, as this judgement depends substantially on the listeners’s off-scale perception.
In previous studies, it was shown that the temporal control in equal-interval tapping is governed by a memory mechanism, which preserves the information of the preceding 20 intervals to determine the interval of the present tap. In the first stage of the present study, an equal-interval tapping experiment was carried out. The results of the experiment confirmed that the 20-interval memory mechanism governs the temporal control of single-finger equal-interval tapping for various tempi. In the following stages of the present study, simple rhythmic patterns were constructed with long and short time values with a 2:1 ratio. The temporal fluctuation in repetitive tapping of these rhythmic patterns was analyzed using Fourier analysis and autoregressive models. The results showed that the 20-interval memory mechanism also governs the temporal control of the tapping for the simple rhythmic patterns: In the case of a rapid tempo, the 20-interval memory mechanism is active for the long time value, whereas in the case of a slow tempo, it is active for the short time value. The point at which the memory mechanism switches between the long and short time values is located around a tempo in which the short time value corresponds to 350 ms.
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