Developing and evaluating a hybrid wind instrument

A hybrid wind instrument generates self-sustained sounds via a real-time interaction between a computed excitation model (such as the physical model of human lips interacting with a mouthpiece) and a real acoustic resonator. Attempts to produce a hybrid instrument have so far fallen short, in terms of both the accuracy and the variation in the sound produced. The principal reason for the failings of previous hybrid instruments is the actuator which, controlled by the excitation model, introduces a fluctuating component into the air flow injected into the resonator. In the present paper, the possibility of using a loudspeaker to supply the calculated excitation signal is evaluated. A theoretical study has facilitated the modeling of the loudspeaker-resonator system and the design of a feedback and feedforward filter to successfully compensate for the presence of the loudspeaker. The resulting self-sustained sounds are evaluated by a mapping of their sound descriptors to the input parameters of the physical model of the embouchure, both for sustained and attack sounds. Results are compared with simulations. The largely coherent functioning confirms the usefulness of the device in both musical and research contexts

Estimations of non-linearities in structural vibrations of string musical instruments

Under the excitation of strings, the wooden structure of string instruments is generally assumed to undergo linear vibrations. As an alternative to the direct measurement of the distortion rate at several vibration levels and frequencies, we characterise weak non-linearities by a signal-model approach based on cascade of Hammerstein models. In this approach, in a chain of two non-linear systems, two measurements are sufficient to estimate the non-linear contribution of the second (sub-)system which cannot be directly linearly driven, as a function of the exciting frequency. The experiment consists in exciting the instrument acoustically. The linear and non-linear contributions to the response of (a) the loudspeaker coupled to the room, (b) the instrument can be separated. Some methodological issues will be discussed. Findings pertaining to several instruments - one piano, two guitars, one violin - will be presented.Comment: 11th Congr\`es Fran\c{c}ais d'Acoustique, Nantes : France (2012

Development and Evaluation of a Hybrid Wind Instrument

A hybrid wind instrument generates self-sustained sounds via a real-time interaction between a computed excitation model (such as the physical model of human lips interacting with a mouthpiece) and a real acoustic resonator. Attempts to produce a hybrid instrument have so far fallen short, in terms of both the accuracy and the variation in the sound produced. The principal reason for the failings of previous hybrid instruments is the actuator which, controlled by the excitation model, introduces a fluctuating component into the air flow injected into the resonator. In the present thesis, the possibility of using a loudspeaker to supply the calculated excitation signal is evaluated; the loudspeaker is placed at the entrance of the resonator (a clarinet-like tube), along with a microphone. This work focusses particularly on two possibilities: using the instrument as a new musical instrument and using it as a tool to carry out wind instrument research. First, a theoretical study facilitates the modelling of the loudspeaker-resonator system and the design of a feedback and feedforward filter to successfully compensate for the presence of the loudspeaker. The prototype is then evaluated using physical models of a single-reed, a lip-reed and a bow-string interaction and using a purely mathematical “polynomial” excitation model. For the design of excitation models, the usefulness of dimensionless and reduced parameter forms is outlined, and a sound prediction theory is presented, enabling the pre-estimation of both amplitude and spectral related features of the self-sustained sounds. The resulting self-sustained sounds are evaluated by a mapping of their sound descriptors to the input parameters of the excitation models, both for sustained and attack sounds. For all excitation models, the sounds produced by the hybrid instrument are shown to match those predicted by simulation. However, the hybrid instrument is more easily destabilised for certain extreme parameter states

Thinking Inside the Box: A New Integrated Approach to Mixed Music Composition and Performance

The Thinking Inside the Box project (TItB) seeks to address pragmatic concerns inherent to mixed music performance, and proposes ways to better consider the sound of the acoustic reality of the concert space at studio composition time. This is achieved through empirical investigation into subversive use of recent developments in hardware and software technologies. The primary concerns are (1) optimising the integration of live instruments and electroacoustic sound in the concert hall environment for both the performers and the public, by carefully choosing loudspeaker types and placement at commission time, and by avoiding sound reinforcement; (2) minimizing for studio composers the insitu trauma of the first live rendition of the piece, by bringing the concert hall acoustic environment into the studio composition process, using convolution reverb to reproduce in the studio the given loudspeaker setup through its impulse responses. This paper presents the conclusions of the project's early experiments in the form of three case study sets, and describes how this approach will be of use for any composer of mixed music

Sound archaeology: terminology, Palaeolithic cave art and the soundscape

This article is focused on the ways that terminology describing the study of music and sound within archaeology has changed over time, and how this reflects developing methodologies, exploring the expectations and issues raised by the use of differing kinds of language to define and describe such work. It begins with a discussion of music archaeology, addressing the problems of using the term ‘music’ in an archaeological context. It continues with an examination of archaeoacoustics and acoustics, and an emphasis on sound rather than music. This leads on to a study of sound archaeology and soundscapes, pointing out that it is important to consider the complete acoustic ecology of an archaeological site, in order to identify its affordances, those possibilities offered by invariant acoustic properties. Using a case study from northern Spain, the paper suggests that all of these methodological approaches have merit, and that a project benefits from their integration

Synchronization of Sound Sources

Sound generation and -interaction is highly complex, nonlinear and self-organized. Already 150 years ago Lord Rayleigh raised the following problem: Two nearby organ pipes of different fundamental frequencies sound together almost inaudibly with identical pitch. This effect is now understood qualitatively by modern synchronization theory (M. Abel et al., J. Acoust. Soc. Am., 119(4), 2006). For a detailed, quantitative investigation, we substituted one pipe by an electric speaker. We observe that even minute driving signals force the pipe to synchronization, thus yielding three decades of synchronization -- the largest range ever measured to our knowledge. Furthermore, a mutual silencing of the pipe is found, which can be explained by self-organized oscillations, of use for novel methods of noise abatement. Finally, we develop a specific nonlinear reconstruction method which yields a perfect quantitative match of experiment and theory.Comment: 5 pages, 4 figure

The problem of offset in acoustic pulse reflectometry

Acoustic pulse reflectometry has become established as a useful non-invasive technique for measuring a variety of duct properties. A sound pulse is injected into the duct under investigation and the resultant reflections are recorded. Suitable analysis of the reflections yields the input impulse response of the duct, from which both its input impedance and its internal dimensions can be calculated. However, an input impulse response measurement made using acoustic pulse reflectometry generally contains an offset. Unless this offset is removed, the application of a bore reconstruction algorithm results in a calculated duct profile which expands or contracts spuriously. In this paper, the offset in an input impulse response measurement is shown to consist of both constant and time-varying components. Methods of preventing or removing these DC and time-varying offsets are proposed and subsequent improvements to the bore reconstruction accuracy are demonstrated

Effect of Changing the Vocal Tract Shape on the Sound Production of the Recorder: An Experimental and Theoretical Study

Changing the vocal tract shape is one of the techniques which can be used by the players of wind instruments to modify the quality of the sound. It has been intensely studied in the case of reed instruments but has received only little attention in the case of air-jet instruments. This paper presents a first study focused on changes in the vocal tract shape in recorder playing techniques. Measurements carried out with recorder players allow to identify techniques involving changes of the mouth shape as well as consequences on the sound. A second experiment performed in laboratory mimics the coupling with the vocal tract on an artificial mouth. The phase of the transfer function between the instrument and the mouth of the player is identified to be the relevant parameter of the coupling. It is shown to have consequences on the spectral content in terms of energy distribution among the even and odd harmonics, as well as on the stability of the first two oscillating regimes. The results gathered from the two experiments allow to develop a simplified model of sound production including the effect of changing the vocal tract shape. It is based on the modification of the jet instabilities due to the pulsating emerging jet. Two kinds of instabilities, symmetric and anti-symmetric, with respect to the stream axis, are controlled by the coupling with the vocal tract and the acoustic oscillation within the pipe, respectively. The symmetry properties of the flow are mapped on the temporal formulation of the source term, predicting a change in the even / odd harmonics energy distribution. The predictions are in qualitative agreement with the experimental observations

I Am Big, It’s the Pictures That Got Small: Sound Technologies and Franz Waxman’s Scores for Sunset Boulevard (1950) and The Twilight Zone’s “The Sixteen Millimeter Shrine” (1959)

Franz Waxman composed over 150 film scores, the most famous of which is Billy Wilder’s film noir Sunset Boulevard (1950). The film plot bears a striking resemblance to Rod Serling’s teleplay for The Twilight Zone, “The Sixteen-Millimeter Shrine” (1959). Waxman, composer of the film, was approached to compose a score for a television episode that was what many term a shortened version of Wilder’s film for the small screen, but with supernatural elements. This article serves to remedy the dearth of literature on this topic and to form an examination of the ways that Waxman conceived of music to accompany films with similar themes but on different screens. Through this comparison of the two scores, a clearer picture of Waxman’s approaches to composing music for moving images will be presented