Acoustic Impedance Measurement, Part I: A Review

Dalmont, Jean‐Pierre

doi:10.1006/jsvi.2000.3428

Cited by 106 publications

(60 citation statements)

References 46 publications

(46 reference statements)

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“…The geometries of the instruments are established through bore profile measurements, made both directly using a set of high precision measurement discs and non-invasively using the technique of acoustic pulse reflectometry 1,2,3 . The strengths and frequencies of the instruments' resonances are determined through measurements of input impedance 4,5,6 . In addition, 4 psychophysical testing 7 is employed to evaluate the abilities of oboists to perceive differences in the playing properties of the instruments.…”

Section: Introductionmentioning

confidence: 99%

Investigating the consistency of woodwind instrument manufacturing by comparing five nominally identical oboes

Mamou-Mani

Sharp

Meurisse

et al. 2012

The Journal of the Acoustical Society of America

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For large-scale woodwind instrument makers, producing instruments with exactly the same playing characteristics is a constant aim. This paper explores manufacturing consistency by comparing five Howarth S10 student model oboes. Psychophysical testing involving nine musicians is carried out to investigate perceived differences in the playing properties of the two Howarth oboes believed to be most dissimilar. Further testing, involving one musician and combinations of the five oboes, provides information regarding the relative playabilities of the instruments at specific pitches. Meanwhile, input impedance measurements are made on the five oboes for fingerings throughout the playing range and their bore profiles are measured. The main findings are (i) the two instruments used in the preliminary psychophysical testing are perceived as identical by most of the musicians, although differences are identified by two players when playing the note F6 and by one player when playing in the lowest register, (ii) a variation in the playability of F6 across the five oboes is due to differences in the elevation of the C key, and (iii) variations in the playing properties in the lowest register are related to input impedance differences which, in turn, appear to be at least partly due to bore profile differences.

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Section: Introductionmentioning

confidence: 99%

Investigating the consistency of woodwind instrument manufacturing by comparing five nominally identical oboes

Mamou-Mani

Sharp

Meurisse

et al. 2012

The Journal of the Acoustical Society of America

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“…The system output should be a time domain impulse response of the object under test. The acoustic response of tubular objects is often determined in terms of an object's planar mode complex input impedance [16]. Although the acoustic impedance is closely related to the impulse response [14], the impulse response is most appropriate as this gives the clearest indication of defect location and associated feature shape.…”

Section: Introductionmentioning

confidence: 99%

Directional wave separation in tubular acoustic systems – The development and evaluation of two industrially applicable techniques

Groves¹,

Lennox²

2017

Applied Acoustics

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An acoustic device is used to evaluate internal features and defects within tubes by determination of the acoustic impulse response. This paper concerns methods of separating the total pressure wave measured in the device into its forward and backward travelling components, which facilitates computation of the acoustic impulse response. The device comprises a tube that has a speaker at one end and is axially instrumented with microphones. Unlike similar works, the methods presented in this paper were designed to be applied in an industrial context, they allow simple calibration and implementation using readily transportable equipment. Two wave separation algorithms are presented; the rst is a known method that has been improved to provide simpli ed calibration and the second is a computationally inexpensive technique that has been adapted to improve its operational bandwidth. The techniques are critically evaluated using a custom built test rig, designed to simulate realistic tube features and defects such as constrictions, holes and corrosion. It is demonstrated that, although inter-microphone attenuation is not accounted for in the second algorithm, both algorithms function well and give similar results. It is concluded that the added sophistication of the rst method means that it is less a ected by low frequency interference and is capable of yielding more accurate results. However, in practical use as an evaluation tool, the bene ts of including inter-microphone attenuation are outweighed by the additional calibration and computational requirements. Finally the output of the wave separation techniques is validated by showing agreement between experimental impulse response measurements and those obtained from a theoretically derived acoustic tube simulator.

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“…Comprehensive reviews of methods realised in the 20 th century can be found in papers by Benade and Ibisi [7] and by Dalmont [8]. Meanwhile, more recent techniques are reported in papers by van Walstijn et al [9], Dickens et al [10], Dalmont and Le Roux [11], Curtit et al [12] and Kemp et al [13].…”

mentioning

confidence: 99%

A Single Microphone Capillary-Based System for Measuring the Complex Input Impedance of Musical Wind Instruments

Sharp¹,

Mamou-Mani²,

Walstijn³

2011

Acta Acustica united with Acustica

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M. (2011). A single microphone capillary-based system for measuring the complex input impedance of musical wind instruments. Acta Acustica united with Acustica, 97 (5) AbstractCapillary-based systems for measuring the input impedance of musical wind instruments were first developed in the mid-20th century and remain in widespread use today. In this paper, the basic principles and assumptions underpinning the design of such systems are examined. Inexpensive modifications to a capillary-based impedance measurement set-up made possible due to advances in computing and data acquisition technology are discussed. The modified set-up is able to measure both impedance magnitude and impedance phase even though it only contains one microphone. In addition, a method of calibration is described that results in a significant improvement in accuracy when measuring high impedance objects on the modified capillary-based system. The method involves carrying out calibration measurements on two different objects whose impedances are well-known theoretically. The benefits of performing two calibration measurements (as opposed to the one calibration measurement that has been traditionally used) are demonstrated experimentally through input impedance measurements on two test objects and a Boosey and Hawkes oboe.

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Acoustic Impedance Measurement, Part I: A Review

Cited by 106 publications

References 46 publications

Investigating the consistency of woodwind instrument manufacturing by comparing five nominally identical oboes

Investigating the consistency of woodwind instrument manufacturing by comparing five nominally identical oboes

Directional wave separation in tubular acoustic systems – The development and evaluation of two industrially applicable techniques

A Single Microphone Capillary-Based System for Measuring the Complex Input Impedance of Musical Wind Instruments

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