Sympathetic Vibrations Research Articles

Contagious Vibrations: Sympathetic Resonance as a Model for Disease Transmission in the Writings of Ficino, Fracastoro, and Cardano.

Contagious diseases were among the most vexing problems in ancient theories of health, which could not easily account for how a corruption of one person's humors could cause a similar corruption in another's. One useful explanatory concept for Renaissance doctors tackling this theoretical gap was the phenomenon of resonance or "sympathetic vibration" - where one stationary string begins to vibrate spontaneously when a similarly tuned string is plucked nearby - as both resonance and contagion involved some mysterious, insensible action at a distance between an agent and a patient. Tracing the writings of Marsilio Ficino, Girolamo Fracastoro, and Girolamo Cardano, this essay explores the relationships between the writers' accounts of sympathetic vibrations and their contagion theories. It argues that different conceptions of the acoustic phenomenon - either as a manifestation of a Neo-Platonic World-Soul that underpinned the universe or else as a physical effect - revealed the writers' cosmological views that, in turn, informed their accounts of the human body and disease.

Sympathetic Vibrations: Sense-ability, Medical Performance, and Hearing Histories of Hurt

Sympathetic Vibrations: Sense-ability, Medical Performance, and Hearing Histories of Hurt

Transient oscillations in steelpan drums tracked via machine learning

Applying a machine learning based object detector to high-speed videos of Caribbean steelpan drums illuminated by laser electronic speckle pattern interferometry (ESPI), we can track the development of sympathetic vibrations in response to drum strikes. This object detector was trained on a dataset of crowdsourced human-annotated images obtained in the Steelpan Vibrations Project on the Zooniverse platform. When the model is used to supply annotations to thousands of unlabeled video frames, we measure visual oscillations at frequencies consistent with audio recordings of these drum strikes. In this talk we share early physics results such as the unanticipated phenomenon of sympathetic oscillations of higher-octave notes that significantly precede the rise in sound intensity of the corresponding second harmonic tones; the mechanism responsible for this remains unidentified.

MUSIC, MORALITY AND SYMPATHY IN THE EIGHTEENTH-CENTURY ENGLISH SERMON

ABSTRACTWhile the furrows of sixteenth- and seventeenth-century religious writing on music have been deeply ploughed, eighteenth-century English sermons about music have received relatively slight scholarly attention. This article demonstrates that the ideas of sympathy and sensibility characteristic of so much eighteenth-century thought are vital to understanding these sermons. There is an evolution in this literature of the notion of sympathy and its link to musical morality, a development in the attitude towards music among clergy, with this art of sympathetic vibrations receiving ever higher approbation during the century's middle decades. By the time that Adam Smith was articulating his Theory of Moral Sentiments (1759) and Handel's oratorios stood as a fixture of English musical life, religious thinkers had cast off old concerns about music's sensuality. They came to embrace a philosophy that accepted music as moral simply because it made humankind feel, and in turn accepted feeling as the root of all sociable experience. This understanding places the music sermon of the eighteenth century within the context of some of the most discussed philosophical, social, literary, musical and moral-aesthetic concepts of the time.

Physics-based modeling techniques of a twelve-string Portuguese guitar: A non-linear time-domain computational approach for the multiple-strings/bridge/soundboard coupled dynamics

The Portuguese guitar is a pear-shaped instrument with twelve metal strings which is widely used in Portuguese traditional music. Unlike most common guitars, it has a curved top-plate and a specific violin-like bridge which is not rigidly fixed to the soundboard of the instrument. From the dynamical point of view, if the bridge transmits the strings vibrations to the instrument body in order to maximize the radiated energy, it also couples all the component parts of the instrument which therefore interact by structural coupling. This can originate various audible effects such as beating behavior and the excitation of numerous sympathetic resonances enhanced by the large number of strings of the instrument, and this is certainly why the Portuguese guitar has such distinct sound compared to other guitars. In this paper, a fully coupled time-domain model of the Portuguese guitar is developed and a series of simulations are presented to emphasize the various coupling phenomena involved in sound production. To reproduce the main musical features, the model includes the coupled dynamics of the twelve strings supported by a bridge which interact with the body of the instrument, described through Finite-Element modeling of the soundboard of a typical Portuguese guitar. Further simple models have been devised for the string/fret interaction and the pluck excitation. Since nonlinear effects are quite apparent in the behavior of string musical instruments, the string dynamics is modeled by the Kirchhoff–Carrier equations which describe large-amplitude string vibrations, and includes the coupling between both polarizations of string motion. The coupling between the strings and the soundboard at the bridge is provided by a model of the bridge kinematics, built on the basis of simple geometrical rationale, so that the two perpendicular string motions can exchange energy back and forth. By a close examination of the energy transfers between the various subsystems of the model, we first assess the correct behavior of the physical model and then examine the respective influence of the string nonlinearity and the bridge on the nonplanar motion of the string. The fully coupled model which pertains to the restricted group of studies which deals with the complete physical-based modeling of a multi-stringed instrument, captures many important phenomena observed in practice, among which the pitch glide effect and the mutual excitation of sympathetic vibrations.

Hands-on demonstrations for Project Listen Up: Education outreach.

Midshipmen from the General Science Major will be getting involved in an ASA education outreach effort by presenting a number of acoustical demonstrations geared to promote a hands-on learning experience for middle- and high-school age girl scouts. The demos are designed to visualize certain sound wave effects that will be explained by the Midshipmen (role models) who hands-off the controls of the apparatus to the students who will be free to participate and make their own scientific discoveries. The demonstrations will be (1) sympathetic vibrations of matched xylophone bars or matched tuning forks mounted in quarter-wave resonant open-ended boxes, (2) tuning fork excitation of standing waves in a sound resonance tube with a variable water column, (3) small inexpensive speaker placed in a hole in a baffle or inside a megaphone generating enhanced sound by eliminating destructive interference effects, (4) interference from two separated loud speaker sources measured vs microphone location, and transverse wave visualizations using a (5) torsion wave machine and (6) a small ripple tank. The traveling and standing wave patterns in (5) and the reflection, refraction, interference, and scattering effects in (6) are helpful wave visualizations and aid in the understanding of longitudinal sound wave effects.

Sympathetic String Modes in the Concert Harp

The concert harp is composed of a soundboard, a cavity with sound holes and 47 strings. When one string is plucked, other strings are excited and induce a characteristic 'halo of sound'. This phenomenon, called sympathetic vibrations is due to a coupling between strings via the instrument's body. These sympathetic modes generate the presence of multiple spectral components in each partial of the tone. Resolution of Fourier analysis does not permit their identification. A high resolution Method, called ESPRIT, is used to separate the spectral components which are very close one to another. Some of the measured spectral components in the analysed partials correspond to the response of sympathetic modes. The eigenfrequencies and mode shapes of these modes are investigated using a suitable model of the instrument : this model is based on a waveguide approach in which bending and longitudinal motions of 35 strings connected to an equivalent beam representing the soundboard are described. Identified experimental sympathetic modes are very well captured by the model.

A study on tooth mobility following periodontal surgery

The purpose of this study was to evaluate the quantitative changes in tooth mobility before and after periodontal surgery using a tooth mobility tester. The tester was so designed as to be able to measure the cycle of sympathetic vibrations produced when a tooth was tapped with a impact hammer. Initially the degrees of tooth mobility, which were clinically classified from 0 to 3, were observed and the mode of mobility was assessed by the tester. Then, we examined the changes of tooth mobility after flap surgery. The following is a summary of findings.

Analysis and modeling of piano sustain-pedal effects

This paper describes the main features of the sustain-pedal effect in the piano through signal analysis and presents an algorithm for simulating the effect. The sustain pedal is found to increase the decay time of partials in the middle range of the keyboard, but this effect is not observed in the case of the bass and treble tones. The amplitude beating characteristics of piano tones are measured with and without the sustain pedal engaged, and amplitude envelopes of partial overtone decay are estimated and displayed. It is found that the usage of the sustain pedal introduces interesting distortions of the two-stage decay. The string register response was investigated by removing partials from recorded tones; it was observed that as the string register is free to vibrate, the amount of sympathetic vibrations is increased. The synthesis algorithm, which simulates the string register, is based on 12 string models that correspond to the lowest tones of the piano. The algorithm has been tested with recorded piano tones without the sustain pedal. The objective and subjective results show that the algorithm is able to approximately reproduce the main features of the sustain-pedal effect.

Acoustic coupling of drum-set cymbals

When playing the standard drum set there is a definite audible coupling between the crash cymbal and the splash cymbal. The purpose of this paper was to evaluate this coupling by studying the spectral signature of each cymbal. Separate recordings were made of a 16-in. (40-cm) thin dark crash cymbal and a 10-in. (25-cm) splash cymbal in an anechoic chamber. Spectra Plus software was used to extract the spectral signature of each cymbal. The two cymbals were then placed in proximity with each other and new recordings were made, striking each cymbal in turn. New combined spectral signatures were extracted showing a change in signature for each cymbal due to cross coupling with the other cymbal. The signatures of sympathetic vibrations produced by the unexcited cymbals were then extracted from the combined spectral signatures using MATLAB software. This experiment provided a better understanding of the nature of the coupling between cymbals and provided the needed data for future study of the actual coupling mechanism.

Unbalanced Operation of HVDC Converters in Asynchronous Linksin Torsional Stressing of Turbine-Generator Shafts

This article analyzes the impact of unbalanced and balancedoperation of HVDC link rectifier bridges on ripple current superimposed on the direct current in asynchronous links in the excitation of torsional vibrations in steam turbine-generator-exciter shafts. The effect of nonideal conditions such as unbalanced rectifier ac supply voltage, unbalanced phase inductance and transformer tappings, and firing errors on the spectrum of dc harmonic voltages compared with the ideal case is discussed. These voltages give rise to dc harmonic currents at the rectifier that may excite sympathetic shaft torsional vibrations in the machine shaft.First, frequencies at which sympathetic shaft torsional vibrations would be excited by modulation product harmonic currents due tounbalanced and balanced operation of 50 Hz/50 Hz asynchronous links as a function of deviation in the system frequency are illustrated. Amplitude of shaft torsional torque due to resonant torque excitation due to harmonic current injected into the ac system by the inverter is then discussed. The article thenconsiders how the steady torque excitation depends on the noncharacteristic harmonic current that is injected into the ac system by the inverter. Tables and graphs are presented to illustrate the significance of bridge unbalances on rectifier harmonic ripple voltage (and hence on the associated currents thatare superimposed on the HVDC line current at the rectifier and subsequently at the inverter), which result in torsional torque in turbine-generator shafts. The relative amplitude of noncharacteristic currents injected into the ac system by the inverter operating unbalanced and balanced is indicated. Both 6- and 12-pulse bridges are analyzed.

Plucked-String Models: From the Karplus-Strong Algorithm to Digital Waveguides and beyond

The emergence of what is called modeling and model-based sound synthesis is closely related to the development of computational simulations of plucked string instruments. Historically, the first approaches (Hiller and Ruiz 1971a, 1971b; McIntyre and Woodhouse 1979; McIntyre, Schumacher, and Woodhouse 1983) were followed by the Karplus-Strong (KS) algorithm (Karplus and Strong 1983). The KS algorithm was discovered as a simple computational technique that seemingly had nothing to do with physics. Soon thereafter, Julius Smith and David Jaffe showed a deeper understanding of its relation to the physics of the plucked string (Smith 1983; Jaffe and Smith 1983). Later, Julius Smith generalized the underlying ideas of the KS algorithm by introducing the theory of digital waveguides (Smith 1987). Digital waveguides are physically relevant abstractions yet computationally efficient models, not only for plucked strings, but for a variety of one-, two-, and three-dimensional acoustic systems (Van Duyne and Smith 1993; Savioja, Rinne, and Takala 1994; Van Duyne, Pierce, and Smith 1994). Further investigations embodied these ideas in more detailed synthesis principles and implementations, resulting in high-quality and realistic syntheses of plucked string instruments (Sullivan 1990; Karjalainen and Laine 1991; Smith 1993; Karjalainen, Valimaki, and Janosy 1993; Vilimaki, Huopaniemi, Karjalainen, and Jainosy 1996). A recent overview of research in this field is given by Smith (1996). The equivalence of Karplus-Strong and digital waveguide formulations in sound synthesis was already known when the waveguide theory appeared (Smith 1987, 1992, 1997); however, the relation has never been explicated in full detail. The first aim of this article is to show how the more physical waveguide model of a plucked string can be reduced to an extended form of the Karplus-Strong type that we call the single delay-loop (SDL) mod l. For a linear and time-invariant (LTI) case, this reduction is relatively straightforward, and results in a computationally more efficient digital filter structure. (Note that the historical order of the KS algorithm and digital waveguides is the reverse of their logical order, since the generalization was not developed until after the KS algorithm was designed. This article's title reflects the historical evolution: the beyond refers to recent generalizations and extensions of both concepts.) The second aim of this article is to discuss further extensions to the basic SDL models that make them capable of simulating plucking styles, beats in string vibration, sympathetic vibrations, and resonant strings. Such techniques have already been proposed and studied (Jaffe and Smith 1983; Smith 1993; Karjalainen, Vilimiki, and Janosy 1993). Here we discuss them in the context of our recent implementations of plucked-string models.

Sound synthesis model incorporating sympathetic vibration of strings

Synthesizer models for emulating musical instruments are improved to take into account sympathetic string vibrations. One embodiment of the present invention scales an output signal from a sound synthesis model (220) and uses the scaled signal as an input signal for a number of single-string emulators (201-212) causing the single-string emulators to produce sound signals corresponding to sympathetic string vibrations. The output signals from the synthesis model (220) and from all of the single-string emulators (201-212) are added together. Another embodiment employs an octave's worth of single-string emulators to emulate the lower strings of an emulated instrument. Still another embodiment is a synthesizer which includes an input bus (220A) for accepting a sound signal, scaling means (244), a plurality of single-string emulators, and means for summing output signals from the string emulators. Embodiments preferably employ waveguide synthesis or the plucked string model to emulate single strings.

TORQUES IN TURBINE-GENERATOR-EXCITER SHAFTS DUE TO DC CURRENTS IN ASYNCHRONOUS HVDC LINKS

ABSTRACT This paper makes an indepth analysis of excitation of shaft torsional vibrations in steam turbine-generator-exciter shafts by variable-frequency ripple currents superimposed on DC currents in asynchronous Links. First, frequencies at which sympathetic shaft torsional vibrations would be excited by modulation product harmonics in 50Hz/50Hz asynchronous Links as a function of deviation in system frequency is illustrated. Then steady-state torque excitation due to injected harmonic stator currents due to the DC ripple currents is analysed. Time constants for decay of shaft torsional vibrations based on electrical and steam viscous damping for generators operating at full-load and no-load for reduced shaft models which are used with the torque excitation to give amplitude of modal torque are also evaluated. Amplitude of shaft torque for a given torque excitation using reduced shaft models is illustated. The effect of generator load on shaft torque which results from resonant excitation for reduced shaft models is also illustrated. Typical shaft torques for generators connected close to HVDC Link inverters which results from resonant excitation by non-characteristic currents at full-load and no-load are also illustrated. Shaft torques in multi-machine networks are estimated by proportioning HVDC Link disturbance current to each machine at risk using system network data, generator data, fault analysis data and load flow data, considering the frequency dependence of the system parameters. 660MW andlOOOMWmachines are considered in the analyses that are made.

Brass instrument improvement

An improvement to the tone and responsiveness of brass instruments is achieved by holding preshaped pieces of damping material, preferably a waxy, hot-melt adhesive, pressed against surfaces of the instrument tubing sections such as valve casings and tubing sections at particular locations, to reduce sympathetic vibrations of the instrument structure.

Method and apparatus for inducing audio vibrations

A method and apparatus of inducing vibrations and buzzes within a vehicle, e.g., from panel trim, provides a reliable and repeatable way to identify the sources of such vibrations and buzzes. According to the method, an FM transmitter modulates and transmits predetermined frequency signals to a standard FM receiver located in the interior of the car. The FM receiver receives and demodulates the signal, and then applies it to audio speakers also located within the vehicle. The output signal from the speakers induces sympathetic vibrations in vehicle components, allowing a tester to identify the sources of the vibrations and buzzes so that they may be corrected. The transmitter provides a means for a user to maintain a constant frequency or to vary the frequency within a predetermined range of frequencies. The frequency may be generated by digitally storing one complete sine wave in successive memory locations. The values can then be retrieved and converted to an analog signal. Higher frequencies are obtained by sampling at a constant rate, but skipping some of the values, thereby retrieving the sine wave at a faster rate.

Analysis of variable-frequency currents superimposed on DC currents in asynchronous HVDC links in stressing turbine-generator-exciter shafts

The paper makes an indepth analysis of the excitation of shaft torsional vibrations in steam turbine-generator-exciter shafts by variable-frequency ripple currents superimposed on DC currents in asynchronous links using the finite element and reduced models of the machine shafts. Frequencies at which sympathetic shaft torsional vibrations would be excited by modulation product harmonics in 50 Hz/50 Hz and 50 Hz/60 Hz asynchronous links as a function of deviation in system frequency are illustrated. It is shown that amplitude of shaft torque due to steady resonant torque excitation is a function of initial rate of increase of vibrations at adjacent cells, the time constant for decay of the vibration, and stiffness between adjacent shaft cells.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Power links with Ireland-excitation of turbine-generator shaft torsional vibrations by variable frequency currents superimposed on DC currents in asynchronous HVDC links

The paper describes an in-depth analysis of excitation of shaft torsional vibrations in steam-turbine-generator-exciter shafts in close proximity to HVDC converter stations by variable-frequency ripple currents superimposed on the DC currents in asynchronous links. It extends earlier work to include an in depth analysis of system scaling factors for harmonic currents impressed on generators in Northern Ireland by an inverter and to investigate the phenomena for possible torsional vibrations in the generators by the link. It is concluded that variable-frequency ripple currents superimposed on the DC current in asynchronous links can excite sympathetic torsional vibrations in turbine-generator-exciter shafts. Subtransient generator reactances may be used to approximately proportion injected harmonic current to each machine of a multi-machine network. Very small noncharacteristic currents could result in serious damage to the machine although possibility of two power systems operating with fixed deviation in system frequencies long enough for the vibrations to build up is remote. Studies should be undertaken as routine on all machines in close proximity to HVDC converter stations to ascertain whether or not the machines are at risk.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Intrinsic surface phonons in amorphous silica

We have detected intrinsic surface phonons in amorphous silica by performing Raman scattering and infrared-reflectivity measurements on samples of porous Vycor glass. Qualitative agreement of our experimental spectra with theoretical calculations provides an identification of the surface features in terms of microscopic atomic motions. We find a sharp Raman-active peak at 980 ${\mathrm{cm}}^{\ensuremath{-}1}$ associated with the stretching vibration of a hydroxyl group against the surface silicon atom to which it is bonded. The corresponding wagging motion of the hydroxyl group appears in the infrared spectrum as a sharp feature at 380 ${\mathrm{cm}}^{\ensuremath{-}1}$. Both the appearance of these surface features as sharp peaks in the spectra and their relative amplitudes in the Raman and infrared spectra can be explained only if the sympathetic vibrations of underlying substrate layers are taken into account. Experimental confirmation of our assignment is provided by the effects of deuteration and adsorbed ammonia molecules on the Raman-active surface modes. Our experiment is the first in which the perturbations of these surface modes due to adsorbed molecules are studied. In our examination of the effects of water adsorption on the Raman spectrum of porous Vycor, we have observed a decrease in the intensity of the bulk defect mode near 600 ${\mathrm{cm}}^{\ensuremath{-}1}$ with increasing water coverage. We also present evidence that the intense scattering background observed in Raman experiments on silica and other oxide surfaces is primarily an intrinsic electronic surface effect.

A theory of memory retrieval.

A theory of memory retrieval is developed and is shown to apply over a range of experimental paradigms. Access to memory traces is viewed in terms of a resonance metaphor. The probe item evokes the search set on the basis of probe-memory item relatedness, just as a ringing tuning fork evokes sympathetic vibrations in other tuning forks. Evidence is accumulated in parallel from each probe-memory item comparison, and each comparison is modeled by a continuous random walk process. In item recognition, the decision process is self-terminating on matching comparisons and exhaustive on nonmatching comparisons. The mathematical model produces predictions about accuracy, mean reaction time, error latency, and reaction time distributions that are in good accord with experimental data. The theory is applied to four item recognition paradigms (Sternberg, prememorized list, study-test, and continuous) and to speed-accuracy paradigms; results are found to provide a basis for comparison of these paradigms. It is noted that neural network models can be interfaced to the retrieval theory with little difficulty and that semantic memory models may benefit from such a retrieval scheme.