Greetings, Ran across an interesting site: If the button on the bottom won't work for you, the address is http://www.speech.kth.se/music/smac03/abs03_link.html ORAL Modeling the longitudinal vibration of piano strings B Bank, L Sujbert Budapest University of Technology and Economics, Department of Measurement and Information Systems, Budapest, Hungary This paper is about the physical modeling of the longitudinal string vibrations in the piano. Informal listening tests show that the longitudinal vibrations play an important role in attack of the sound, and are responsible for the metallic character of low notes. However, their modeling has not yet been considered in the literature. First, a simple mathematical model is developed for qualitative understanding. The longitudinal vibration is made up of the free vibration of the longitudinal modes, and a forced vibration coming from a second-order nonlinearity. For the latter, a closed-form solution is given in the case of sinusoidal transversal displacement with non-rigid termination. To investigate how these effects develop in more natural circumstances, finite difference string and hammer models are used, with parameters taken from real pianos. The results are compared to piano measurements. The aim of this study, besides a better insight to the underlying physics, is to develop sound synthesis methods. Therefore, an efficient modeling approach is presented, which can be used with digital waveguide string models. The approximation is based on neglecting those effects, which have less importance from the perceptual point of view. Sound examples will be presented as a part of the talk at the SMAC2003 Conference. POSTER Quality of treble piano tones A Galembo Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Lab 32, St. Petersburg, Russian Federation In this study it is shown that the quality of a treble tone of the piano is defined primarily by the temporal dynamics of the perceptually competing impact noise ("knock") and the string-born tonal element (the partials responsible for pitch sensation). The relation between the two elements depends primarily on the parameters of the hammer-string contact, and not so much on the soundboard properties. The knock component is "colored" by the metal frame, in particular by the choice of material. Two ways (mechanical and electronic) of experimentally separating the knock and the tonal element in a real piano tone for listening tests and demonstrations are shown. (The paper presents results of previous industrial research conducted in the acoustic laboratory of the Leningrad Piano Factory, Russia to English readers.) POSTER Phase randomisation in piano bass tones A Galemboÿ, A Askenfeltÿ ÿSechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Lab 32, St. Petersburg, Russian Federation; ÿKTH, Dept. of Speech, Music and Hearing, Stockholm, Russian Federation It has been shown that the timbre of synthesized multi-component harmonic bass tones with steady magnitude spectrum depends on the phase spectrum, particularly on the randomness of the relative phases between partials [Galembo et al, JASA 110, 1649-1666]. For inharmonic spectra (as in the piano), the waveform will be non-stationary due to the temporal evolution of the phase relations. This creates audible attack transients which are characteristic for the particular starting phases. The relevance of these findings for the perception of real piano tones has been unclear. A piano tone shows a complex dynamic evolution of the spectrum during attack and decay, which besides inharmonicity, is influenced by the properties of the sound board and room reverberation. In this pilot study it is shown that frequency sweeps and associated pitch glides due to phase rotation introduced by string inharmonicity are present in real piano bass tones. The evidence is clear in the string and bridge velocities, and also in the radiated sound close to the piano, although to a lesser extent. POSTER Measurement and reproduction accuracy of computer-controlled grand pianos W Goeblÿ, R Bresinÿ ÿAustrian Research Institute for Artificial Intelligence, Vienna, Austria; ÿRoyal Institute of Technology (KTH), Department of Speech, Music, and Hearing (TMH), Stockholm, Sweden The recording and reproducing capabilities of a Yamaha Disklavier grand piano and a Bösendorfer SE290 computer controlled grand piano were tested, with the goal of examining their usefulness for performance research. An experimental setup consisting of accelerometers and a calibrated microphone is used to capture key and hammer movements, as well as the acoustic signal. Five selected keys are played by pianists with two types of touch ('staccato - legato'). Timing and dynamic differences between the original performance, the corresponding MIDI file recorded by the computer-controlled pianos, and its reproduction are analyzed. The two devices performed quite differently with respect to timing and dynamic accuracy. The Disklavier's onset capturing is slightly more precise (+/-10 ms) than its reproduction (-20 to +30 ms), the Bösendorfer performs generally better, but its timing accuracy is slightly less precise for recording (-10 to 3 ms) than for reproduction (+/-2 ms). Both devices exhibit a systematic (linear) error in recording over time. In the dynamic dimension, the Bösendorfer shows higher consistency over the whole dynamic range, while the Disklavier performs well only in a wide middle range. Neither device is able to capture or reproduce different types of touch. ORAL The piano action as the performer's interface: Timing properties, dynamic behaviour and the performer's possibilities W Goeblÿ, R Bresinÿ, A Galemboÿ ÿAustrian Research Institute for Artificial Intelligence (ÖFAI), Vienna, Austria; ÿRoyal Institute of Technology (KTH), Department of Speech, Music and Hearing (TMH), Stockholm, Sweden A concert pianist is able to produce every imaginable nuance of expression by handling the 88 keys of his/her piano, no one of which travelling through a greater distance than one centimeter. In this study, we investigate the temporal behaviour of grand piano actions by different manufacturers with different types of touch ('legato' versus 'staccato'). An experimental setup consisting of accelerometers and a calibrated microphone was used to capture key and hammer movements, as well as the acoustic signal. Five selected keys were played by pianists with the two types of touch. The analysis of the three-channel data was automated by computer software. Discrete measurements (e.g., finger-key, hammer-string, key bottom contact times, hammer velocity) were extracted for each of the 2563 recorded tones in order to study several temporal relations. Travel times of the hammer (from finger-key to hammer-string) as a function of hammer velocity varied clearly between the two types of touch, but only slightly between the pianos. A travel time versus hammer velocity function found in earlier work derived from a computer-controlled piano could be replicated. Key bottom contact times exhibit larger variability between types of touch and pianos. However, no effect of touch type was found in the peak sound level (in dB as a function of hammer velocity). This finding raises once again the question whether other factors than hammer velocity influence the tone of the piano. Piano string vibration and problems of its numerical modeling A Raffaj Petrof, spol. s r.o., Research dept., Hradec Kralove, Czech Republic The specifities of a piano string vibration and their influence on a final piano sound timbre are summarized. The numerical model of a piano string was created by means of the finite difference methods (FDM). As piano hammer model which excites virtual piano string was used non-linear hereditary (hysteretic) hammer model introduced by Stulov. The dynamical force-compression characteristics of piano hammer are measured on the special measuring apparatus, which will be described and compared to the Stulov's apparatus. The measured results is compared to piano hammer properties measurements which are done usually by hammer manufacturers. A brief discussion of hammer properties influence on final piano timbre is presented. For the simulation of reality the real soundboard was excited by shaker which is supplied by computed signal. This signal is proportional to force transmitted from string to the bridge. In this way is aurally judged the influence of string qualities, way of hammer manufacturing and quality changes during the voicing. At the conclusion the possibilities of the numerical model improving by addition of the longitudinal modes simulation and non-linearity transfer of string vibration to the bridge is presented. ORAL The piano soundboard behaviour in relation with its mechanical admittance J S Skala Petrof , spol s.r.o., Research, Hradec Kralove, Czech Republic Piano soundboard input mechanical admittance was investigated in wide frequency range. In lower frequency range strong differences between peak and pit values have been observed. With the increasing frequency, the wrinkled character of soundboard admittance is changed to more smooth one, due to a coupling of modes. The idea was to compare piano soundboard behaviour upon driving by shaker supplied with simple harmonic force signal on near peak and pit (mode + antimode) frequency. The measurement was made on soundboard fixed to backframe and iron frame without strings. We expect that on antimode frequency the soundboard radiation will be very poor. The final perceived sound volume differs less than it has been expected. A discussion if rest of sound energy can be leakaged out more either on other frequency partials by soundboard or by other piano parts (iron frame, rim) is included. This effect is one (but not only one) reason for we can hear a piano tone with frequency in which level of the soundboard admittance is very low. ORAL Experimental and theoretical studies of piano hammer A Stulov Institute of Cybernetics at Tallinn Technical University, Centre for Nonlinear Studies, Tallinn, Estonia Based upon the large number of experimental data obtained using a special piano hammer testing device, it has been shown, that all the present-day piano hammers have as a quality the hysteretic type of the force-compression characteristics. This not a chance because such a hysteretic character has been developed step-by-step following the history of evolution of piano hammers since the instrument was created. The dynamical behaviour of the contemporary piano hammer can be described by different mathematical hysteretic models. In addition to the four-parameter nonlinear hysteretic model of piano hammer, another new a three-parameter hysteretic model was developed. This is very similar to the nonlinear Voigt model and permits a description of the dynamical hammer felt compression that is consistent with experiments. The both models are based on an assumption that the hammer felt made of wool is a microstructural material possessing history-dependent properties. The equivalence of these models is proved for any realistic values of hammer velocity. The continuous dependencies of the hammer parameters on the key number are obtained, which is the first known case of such an analysis. The application of hysteretic models to numerical simulation of the grand piano hammer-string interaction is demonstrated. The flexible string vibration spectra excited by different piano hammers are analysed. All that together, leads to a new method for piano stringing-scale design. Click Here: <A HREF="http://www.speech.kth.se/music/smac03/abs03_link.html"> S M A C 0 3</A> <A HREF="http://www.speech.kth.se/music/smac03/abs03_link.html"> </A> Ed Foote RPT http://www.uk-piano.org/edfoote/index.html www.uk-piano.org/edfoote/well_tempered_piano.html
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