Using Schlieren imaging to estimate the geometry of a shock wave radiated by a trumpet bell

Rendón, Pablo L.; Velasco-Segura, Roberto; Echeverría, Carlos; Porta, David; Pérez-López, Antonio; Vázquez-Turner, R. Teo; Stern, Catalina

doi:10.1121/1.5063810

Cited by 3 publications

(3 citation statements)

References 11 publications

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“…Secondly, the acoustic center of the trombone moves inside the trombone as the frequency increases [24]. In addition, when the secondary sources rotate over 360°, the distance between each receiver and each source varies.…”

Section: Power Minimizationmentioning

confidence: 99%

Study of the optimal active control of a trombone

et al. 2022

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In the brass instrument family, the sound can be modified or attenuated using a mute, which is usually inserted in the bell of the instrument. The objective of this paper is to study the principle and the technological feasibility of an active mute using loudspeakers placed in front or around the instrument bell. This mute must reduce the acoustic power emitted by the instrument while avoiding any impact on its playability. At this stage, an optimal control is considered and no real-time controller is implemented. Results show that an active control placed outside the trombone is theoretically feasible and can be efficient to reduce the acoustic power up to 2000 Hz by placing a ring of sources around the bell and a source in front of the trombone. The instrument input impedance is very slightly affected by the control. In accordance with numerical simulations, the experiment showed that placing a control speaker very close in front of the bell of the instrument modifies the pressure field of the instrument in such a way that it allows to obtain a power attenuation greater than the predicted one. The control is technologically achievable but requires a high power for the closest source.

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Section: Power Minimizationmentioning

confidence: 99%

Study of the optimal active control of a trombone

et al. 2022

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“…where P m (x) is the m-th order Legendre polynomial. Equation (9) indicates that any axisymmetric sound field can be determined by the set of expansion coefficients a m .…”

Section: Physical Model Of Axisymmetric Sound Fieldmentioning

confidence: 99%

“…Such measurements are extensively used for various applications, e.g. imaging of sound fields generated by transducers [2][3][4][5], measurement of sound radiated by musical instruments [6][7][8][9], and calibration of microphones [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Physical-model-based reconstruction of axisymmetric three-dimensional sound field from optical interferometric measurement

Ishikawa

Yatabe

Oikawa

2020

Meas. Sci. Technol.

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Optical interferometric measurement methods for sound fields have garnered considerable attention owing to their contactless nature. The capabilities of non-invasive measurement and reconstruction of three-dimensional sound fields are significant for characterizing acoustic transducers. However, three-dimensional reconstructions are typically time consuming because of the two-dimensional scanning and rotation of the measurement system. This paper presents a scan and rotation-free reconstruction of an axisymmetric sound field in the human hearing range. A physical-model-based algorithm is proposed to reconstruct an axisymmetric sound field from optical interferograms recorded using parallel phase-shifting interferometry and a high-speed polarization camera. We demonstrate that audible sound fields can be reconstructed from data measured in 10 ms. The proposed method is effective for the rapid evaluation of axially symmetric acoustic transducers.

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Low-noise optical measurement of sound using midfringe locked interferometer with differential detection

Ishikawa

Shiraki

Moriya

et al. 2021

The Journal of the Acoustical Society of America

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A midfringe locked interferometer with differential detection is proposed for non-contact optical sound measurement, and the equivalent noise level of approximately 0 dB SPL/Hz is achieved. The noise level of the proposed method is 30 dB lower than that of a very recent laser Doppler vibrometer and close to that of a quarter-inch measurement microphone. The midfringe locking stabilizes the optical interferometer against slow environmental fluctuations and enables detection of the acoustic signal directly from optical intensity. The differential detection method eliminates laser intensity noise, which is a dominant noise source in optical interferometers. The noise level of the constructed system was approximately 10 dB above the optical shot-noise (the classical detection limit attributed to the quantum nature of light) at frequencies higher than 2 kHz. Further noise reduction by several available methods could lead to optical measurements that are more sensitive than measurements by microphones. In addition, the constructed interferometer is used to reconstruct sound fields generated by a half-inch laboratory standard microphone used as a transmitter. The proposed method will be a powerful tool for measuring small-amplitude sound fields where it has been challenging to use existing methods.

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Using Schlieren imaging to estimate the geometry of a shock wave radiated by a trumpet bell

Cited by 3 publications

References 11 publications

Study of the optimal active control of a trombone

Study of the optimal active control of a trombone

Physical-model-based reconstruction of axisymmetric three-dimensional sound field from optical interferometric measurement

Low-noise optical measurement of sound using midfringe locked interferometer with differential detection

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