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͑ a ͒ Exploded view of the ten hole diatonic harmonica showing the upper, blow reed plate, the lower, draw reed plate and the separating comb. 

͑ a ͒ Exploded view of the ten hole diatonic harmonica showing the upper, blow reed plate, the lower, draw reed plate and the separating comb. 

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Article
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The harmonica is arguably the most widely played instrument in the world, yet there is a surprising paucity of published studies of its acoustics or physical dynamics. The typical diatonic harmonica and the physical forces involved in its natural function are described, and simple observations of the harp's functions are reported. The speaking of t...

Contexts in source publication

Context 1
... active element of the harmonica is a metal reed with one end fastened to the surface of a thin metal plate; the other end is free to vibrate. All but the fastened end of the reed overlies a slot in the reed plate that is just large enough to allow the reed to vibrate freely in the slot Fig. 1a, b. The reed is activated by the flow of air across it. It vibrates at a frequency which is near its natural i.e., plucked fre- quency. This frequency is determined by the mass and stiff- ness of the reed in cooperation with its associated acoustical system. The throttling action of the reed on the flow of air causes a periodic ...
Context 2
... apparatus allowed more pure and complete overblows to be achieved than could be obtained with oral playing. Figure 10 shows the detailed waveforms of reed displacement for a sustained hole-3-overblow. The minimal activity of the blow reed noted here was not always easily obtained and sustained when the harp was played by mouth. ...
Context 3
... distinguishing characteristics of the overblow as compared to the bend are further illustrated by comparing the amplitude versus frequency plot of an overblow Fig. 11 with that of a bend Fig. 9. Unlike the bend, which displays a smooth and gradual transition of reed primacy as the fre- quency changes, the overblow demonstrates a much sharper drop in the amplitude of oscillation of the closing, blow reed and simultaneous rise in amplitude of oscillation of the open- ing, draw reed. The interval ...
Context 4
... resulting overlap in frequency response of the two reeds during bending allows the player not only to bend more easily, but to slide between bent and straight notes. Consequently, this provides more opportunity to introduce expression into the notes being played. An example of this is depicted in Fig. 12 which shows a tracing of the amplitude of reed vibration compressed in time and recorded during a 6- draw to 6-draw-bend, played by Howard ...
Context 5
... this case, the vibration of the two reeds remained synchronized but assumed different funda- mental frequencies. Figure 13a and b shows, respectively, a consonant and dissonant overblow obtained in hole 3. In the case of the dissonant 3-overblow, the draw reed, with a natural pitch of B 494 Hz, was induced to vibrate at 518 Hz, but the blow reed with natural pitch of G 392 Hz vi- brated at 358 Hz approximately F with an apparent 25% modulation in its period from cycle to cycle. ...
Context 6
... a simple experiment was conducted in which a player, lying supine, played spe- cific fashioned notes and then held the configuration of the vocal tract while the oral cavity was filled with water and the required volume was recorded. Reproducible results were obtained with practice. The results of this preliminary experi- ment are shown in Fig. 14. It is probable that actual playing volumes were larger than measured, since when water was instilled, constriction of the glossopharynx and larynx oc- curred in order to suppress the swallow reflex and prevent aspiration. The volume of the anterior oral cavity was found to be inversely related to pitch as modified by bending. This ...
Context 7
... allows the player to speak with his instrument perhaps as with no other. Just as no two voices are exactly alike, each player imparts his own timbre, and one cannot expect to emulate exactly the musical tonality of another. This helps keep the harmonica interesting, and indeed has helped to sustain its enduring prominence throughout the world FIG. 14. Volume of oral tract used to play the scale with 1 and 4 draw bends. Harps keyed in the scale of F were used on which hole 1 draw bend circles, or for the higher scale, hole 4 draw bend squares were played. The resulting scale is in the key of F#. The player held the configuration of the vocal tract as the volume of water required to ...

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Citations

... jako zabawka albo urządzenie do strojenia organów, ale udoskonalona znalazła miejsce w muzyce rozrywkowej i występuje do dziś w różnych odmianach. Istotną cechą było umieszczenie w każdej ramce dwóch stroików -jednego pracującego przy wdychaniu, a drugiego przy wydychaniu powietrza przez grającego, z których każdy generuje dźwięk o innej wysokości [Bahnson i in. 1998]. Wynikają z tego niewielkie możliwości muzyczne, ale również niewielkie rozmiary. ...
Thesis
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The blown idiophones are musical instruments in which a reed in a form of a thin bar having its own stiffness takes the role of the vibrator and a stream of air the role of the actuator. The resonator can take various forms. This category contains among others: the accordion, the harmonium (the reed organ), the harmonica and the lingual organ pipes. The conducted research concerns the dependence of the vibration patterns and the quality of generated sound on the free reed width. The current state of knowledge regarding the operation of the blown idiophones has been depicted. The measurements of the acoustic pressure using a microphone probe and of the reed vibrations using a laser vibrometer have been performed for an established model of the instrument, which enables including reeds of a varied width. The numerical modal analysis and the three-dimentional transient numerical simulations of the fluid-structure interaction have been conducted for a computer model of the system with various reeds. It has been shown, that the narrower reeds perform torsional motions during the sound generation. The flow instabilities responsible for the excitation of the torsional vibrations have been indicated. The greatest ratio of the amplitudes of the higher harmonics in relation to the amplitude of the fundamental has been obtained for the middle width reed.
... MRI images [ESBRH 13] show a narrow constriction between tongue and palate together with a well-defined front cavity volume. A measured [BAB98] correlation between playing frequency of various bend notes and front cavity volume suggest that constriction and front cavity together form a Helmholtz resonator, whose resonance frequency has a decisive influence on the periodicity of the self-excited oscillations of airstream and reeds. On the contrary, measurements in [J 87] with a blues harmonica excited by a tube resonator suggest a less intuitive interaction between resonator and reeds. ...
... A blues harmonica (blues harp) 1 is a diatonic harmonica with ten channels [BAB98]. In each channel there is a blow reed and a draw reed. ...
... Bahnson and Antaki [BAB98] conducted an experiment with a professional player (Howard Levy) who played different bend notes and then held the configuration of the vocal tract while the oral cavity was filled with water and the required volume was mea-sured. For draw bends on channels #1 and #4 on harps in different keys they found the values depicted as blue dots in fig. 4. As mentioned by the authors, these values are the volumes of the anterior oral cavity rather than the total oral volumes 5 . ...
... 2 Derivation of an admittance formula Blues harps A blues harmonica (blues harp) 1 is a diatonic harmonica with ten channels [BAB98]. In each channel there is a blow reed and a draw reed. ...
... This constriction together with the anterior oral cavity defines a Helmholtz resonator. [BAB98] measured values of the cavity volume of a professional player (Howard Levy) when playing half-tone draw bends on various harmonicas. In [Fö-R] these volume values together with values for length and area of the constriction of another player (David Barrett) playing an half-tone bend [ESBRH 13] are plugged into the Helmholtz resonator formula. ...
... In [Fö-R] these volume values together with values for length and area of the constriction of another player (David Barrett) playing an half-tone bend [ESBRH 13] are plugged into the Helmholtz resonator formula. The calculated resonance frequencies are in quite good agreement with the respective playing frequencies in [BAB98]. This result likewise suggests that the vocal tract could be modeled by a single-mode resonator. ...
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An explicit formula for the admittance of the reeds system in a channel of a blues harp is derived in a straightforward way. The derivation is tailor-made for the blues harp, and the dual role of the vocal tract as resonator and pressure reservoir is addressed from the outset. The surfaces of moving reeds cause volume flows similar to the moving membrane of a loudspeaker, a contribution to the admittance of the reeds which is taken into account. No measurements or calculations of the vocal tract admittance during blues harp playing seem to exist. Therefore, a single mode resonator as a toy model is used. The admittance of the reeds system in channel #4 of a C-harp is calculated with self-measured parameter values. Linear stability analysis in the complex plane gives necessary conditions for possible playing frequencies. The results are compared with playing experience, documented by own measurements.
... In the case of pipe #1, a different pitch is produced whose frequency is lower than the eigenfrequency of the tongue, while pipes #2 and #3 produce the same pitch (but very different timbre) when played by blowing or suction. The phenomenon observed in the case of pipe #1 might be similar to the pitch bending reported in the case of the diatonic harmonica; 15,21,25 however, different suction conditions could not be examined in detail with our measurement apparatus. If the resonator is damped, the frequency f damp becomes closer to that of the tongue in all cases. ...
Article
This paper presents the experimental examination of an alternative lingual organ pipe construction that uses a free tongue which, in contrast with traditional lingual organ pipes, operates in a blown open manner. A possible advantage of the construction is that it can enable changing the windchest pressure and thus, achieving an extended dynamic range while keeping a constant pitch. Three experimental pipes with diverse resonator shapes are investigated in various setups. The three pipes also demonstrate the variety of timbres obtainable by different configurations of tongues and resonators. The analysis of the measurement results shows that the pipes exhibit a very good stability of the fundamental frequency and can have a dynamic range of 15 dB. At the same time, the timbre of the sound is found to change significantly as the windchest pressure is increased. Experiments performed with damping the resonator reveal the working principle of the tongue-resonator coupling in the alternative construction. Several sound recordings are presented as multimedia file attachments enabling the subjective comparison of the pipe sounds.
... Avery extensive revision of the previous research made on the free reed dynamics is done by Millot and Baumann in [2]: most of the articles dealing with the modelling of free reeds are only concerned with frequencydomain approach and the threshold of reed auto-oscillation [3,4,5,6,7,8,9,10]. Fewer works deal with the dynamics of the free reed [10,11,12,13,14,15]. ...
... Avery extensive revision of the previous research made on the free reed dynamics is done by Millot and Baumann in [2]: most of the articles dealing with the modelling of free reeds are only concerned with frequencydomain approach and the threshold of reed auto-oscillation [3,4,5,6,7,8,9,10]. Fewer works deal with the dynamics of the free reed [10,11,12,13,14,15]. Several attempts have been made to derive amodel for the free reed [2,16,17,18], the last twotexts focusing on the particular case of the accordion. ...
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Accordion players distinguish between bellows attacks and finger attacks. In bellows attacks the button (or key) is pressed first and the bellows are moved after. In finger attacks, the bellows are set in motion (by pulling or squeezing them) and soon afterward the button is pressed down. In this work these two different and characteristic types of attacks are documented and compared, and the relationships between the control of the instrument, the generated sounds, and how these are perceived are analysed. Finally, a characterization of these two different types of attacks is given in terms of the duration of the attacks, the beginning and ending of the first harmonics and the evolution of some psychoacoustic parameters.
... The reed then begins vibrating and grows to its steady state amplitude [2]. There has been much research done already on the steady-state vibration of free reeds [3][4][5][6][7] but relatively little on their attack transients. ...
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Attack transients of harmonium-type reeds from American reed organs have been studied in a laboratory setting with the reeds mounted on a wind chamber. Several methods were used to initiate the attack transients of the reeds, and the resulting displacement and velocity waveforms were recorded using a laser vibrometer system and electronic proximity sensors. The most realistic procedure had a pallet valve mechanism simulating the initiation of an attack transient that depressing an organ key would provide. Growth rates in vibrational amplitude were then measured over a range of blowing pressures. Although the fundamental transverse mode is dominant in free reed oscillation, the possibility of higher transverse modes and torsional modes being present in transient oscillation was also explored. The reeds studied are designed with a spoon-shaped curvature and a slight twist at the free end of the reed tongue, intended to provide a more prompt response, especially for larger, lower-pitched reeds for which a slow attack can be a problem. The effectiveness of this design has been explored by comparing these reeds with equivalent reeds without this feature. [Work supported by National Science Foundation REU Grant PHY-1004860.].
... Several investigators have described the movement of the harmonica reeds during bending. (Bahnson et al, 1998, Antaki JF et al, 2011, Brock and Cottingham, 2011 while others have discussed mechanisms and proposed models of the changes in the vocal tract responsible for bending (Johnston, R.B., 1987, Millot. L. et al,2001, Cottingham J., 2011, Levy H., 2011. ...
Article
Full-text available
Skilled harmonica players learn to bend the pitch of certain notes by a semitone or more, especially in blues playing, by adjusting the shape of their vocal tract [Bahnson et al., J. Acoust. Soc. 103, 2134 (2008)]. The changes of the vocal tract have been partially viewed with endoscopy and ultrasound but are still incompletely understood. While in a magnetic resonance imaging (MRI) scanner, a professional harmonica player using nonmagnetic, MRI-compatible diatonic harmonicas played draw and blow notes in both unbent and bent positions. Three-dimensional static and two-dimensional real-time magnetic resonance images of the upper airway were recorded in the sagittal and coronal planes. We identified and characterized the static and dynamic changes that facilitated pitch bends for low and high notes with specific attention to tongue positioning, tongue morphology, and airway shape. Deliberate changes in the tongue shape are often accompanied by changes in other parts of the vocal tract such as the pharynx.
... 2,4 Bahnson's interest in the harmonica was the subject of a front-page article in The Wall Street Journal, 11 a video, 12 and his final peerreviewed manuscript in 1998, which was published in a music journal, the Journal of the Acoustical Society of America. 13 In April 1977, Bahnson presided over the 57th Annual Meeting of the AATS in Toronto. He was the senior author of an important paper at this meeting regarding subvalvular aortic stenosis, 14 and he also delivered his presidential address, ''Our Obligation to Developing Nations.'' ...
... Significant acoustical studies of pitch bending in the harmonica include early work by Johnston 7 and more recent work headed by Millot 13 and Henry Bahnson. 14 Figures 4a and 4b show the construction of a harmonica and how two reeds are affixed to each reed chamber. ...
Article
Free-reed instruments fall into two related but distinct families: Asian mouth organs of ancient origin and Western instruments that originated in Europe about 200 years ago. The Western free-reed instruments include the harmonica and the "squeezeboxes," the various forms of accordion and concertina. In their relatively short lifetime, those instruments in particular have come to be employed in almost all genres of music and, throughout the world, are among the most widely played. Yet until the late 20th century, only a small amount of acoustical research focused on free-reed instruments. During the past two or three decades, however, interest has surged, and researchers in musical acoustics have devoted a much greater amount of attention to them. To be sure, more papers are written about the trumpet, the clarinet, and the violin. But an indication of the increase in research interest in free reeds in the 1990s is the inclusion of a section in the second edition of The Physics of Musical Instruments (Springer, 1998), by Neville Fletcher and Thomas Rossing, that provides a summary of the research. The first edition of seven years earlier had no such section.
... One can find a great deal of works related to striking reed auto-oscillation [2,3,4,5,6,7,8,9,10] and synthesis of the clarinet or saxophone [11,12,13,14] for instance. But there are far less works related to free reeds dynamics [15,16,17,18,19] and most of the articles dealing with modelling of free reeds are only concerned with frequency-domain approach and the threshold of reed auto-oscillation [20,21,22,23,24,25,26,27,28]. To have an idea of most of the latest available information on free-reed modelling, the reader is invited to search in [29]. ...
... One can note that the variations of the overpressure are significant and that the velocities are important, above all in the free jet at the downstream of the reed which give high Reynolds numbers. lower than the eigen frequency for the (-,+) reed and higher for the (+,-) reed as predicted by Helmholtz [1] and experimentally verified by Jonhston [24], Millot [34,35] or Bahnson [16]. On Figure 21, we have plotted the evolution of the magnitude of the over-pressure ∆p 2 as a function of L 1 . ...
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In this paper we propose a minimal model for free reeds taking into account the significant phenomena. This free reed model may be used to build models of free reed instruments which permit numerical simulations. Several definitions for the section by which the airflow passes through the reed are reviewed and a new one is proposed which takes into account the entire escape area under the reed and the reed thickness. To derive this section, it is necessary to distinguish the neutral section (the only section of the reed which always keeps its length constant while moving) from the upstream or downstream sections. A minimal configuration is chosen to permit the instabilities of both (−,+) and (+,−) reeds on the basis of a linear analysis of instabilities conditions. This configuration is used to illustrate, with temporal simulations, the minimal model for both kinds of reeds and to discuss the model assumptions. Some clues are given about the influence, on the playing frequency and on the dynamic of the sound, of two main parameters of the geometrical model: the size of the volume and the level of the excitation. It is shown that the playing frequency of a (+,−) reed can vary in a large range according to the size of the volume upstream of the reed; that the playing frequency is nearly independent of the excitation but that the dynamic of the sound increases with the excitation level. Some clues are also proposed to determine the nature of the bifurcation for free reeds: it seems that free reeds may present inverse bifurcations. The influence of the reed thickness is also studied for configurations where the reed length or the reed width vary to keep the mass constant. This study shows that the reed thickness can have a great influence on the sound magnitude, the playing frequency and the magnitude of the reed displacement which justifies its introduction in the reed model.