scholarly journals Measurement of "Reed to Room"-Transfer Functions

2019 ◽  
Vol 105 (6) ◽  
pp. 899-903
Author(s):  
Timo Grothe ◽  
Sebastià V. Amengual Garí
Keyword(s):  
Transfer Functions ◽  
Radiative Properties ◽  
Room Acoustics ◽  
Response Measurement ◽  
Wind Instrument ◽  
Source Signal ◽  
Distant Measurement ◽  
Column Pressure ◽  
Peak Pressures ◽  
Air Column

A method is proposed here to synthesize the acoustic response of a room to a musical reed wind instrument with tone holes played by a musician. The procedure uses convolution of a) two measured pulse responses and b) the mouthpiece pressure during playing. The novelty of the approach is to include the sound radiation directivity of the source in the impulse response measurement of the room by using the wind instrument's air column as an exciter. At the reed input end of the air column pressure pulses at typical peak pressures of several kilopascals are generated using a compressor and a solenoid valve, which provides a high SNR even at distant measurement positions. For auralization purpose, the source signal measurement is done very close to the sound generation locus, i.e. inside the mouthpiece. Because this measurement is largely insensitive to room acoustics, the proposed method can be considered a very convenient alternative to music recordings in anechoic conditions. As a proof of concept we report here experimental results for the case of a bassoon. The method can be extended to auralizations of reed and lip-reed musical instruments in virtual acoustic scenes, and sheds light on the importance of the reflective and radiative properties of the air column for the sound coloration.

Blind Identification of Impact Forces From Multiple Remote Vibratory Measurements

2000 ◽  
Author(s):  
J. Antunes ◽  
P. Izquierdo ◽  
M. Paulino
Keyword(s):  
Explicit Knowledge ◽  
Transfer Functions ◽  
Dynamical Behavior ◽  
Practical Interest ◽  
Operating Conditions ◽  
Blind Identification ◽  
Minimum Entropy ◽  
Response Measurement ◽  
Identification Techniques ◽  
The Impact

Abstract Structures and mechanical components are often subjected to impulsive forces. There is a need for identification techniques which enable monitoring of such loads under operating conditions. For safety reasons and convenience, force identification must often be based on response motions sensed at accessible locations, remote from the impact points. In our previous work we presented techniques for the experimental identification of both isolated impacts and complex rattling forces on a beam, generated at a single and also at several impacting supports. The system dynamical behavior was modeled using traveling flexural beam waves. Although successful, these techniques obviously assume a good understanding of the system dynamic parameters. This is not always the case, a fact that highlights the practical interest of blind identification techniques. This relatively recent field, connected with higher-order statistics, avoids any explicit knowledge of the system transfer functions or impulse responses. Our previous work, based on a single response measurement, is extended in this paper to include several simultaneous responses. We develop a multi-trace version of Wiggins minimum-entropy blind deconvolution algorithm. From numerical simulations and experiments, it is shown that the robustness to noise contamination is increased by using multiple response data. These results suggest that blind identification techniques will prove very useful in practical situations.

Effect of bending portions of the air column on the acoustical properties of a wind instrument

2008 ◽  
Vol 123 (5) ◽  
pp. 3447-3447
Author(s):  
Simon Félix ◽  
Cornelis J. Nederveen ◽  
Jean‐Pierre Dalmont ◽  
Joël Gilbert
Keyword(s):  
Acoustical Properties ◽  
Wind Instrument ◽  
Air Column

A simple air pressure gauge for unsaturated soils

2007 ◽  
Vol 44 (8) ◽  
pp. 1013-1018 ◽  
Author(s):  
Julio  Ángel Infante Sedano ◽  
Sai K. Vanapalli ◽  
Vinod K. Garga
Keyword(s):  
Unsaturated Soils ◽  
Low Cost ◽  
Pressure Gauge ◽  
Matric Suction ◽  
Coarse Grained ◽  
Water Characteristics ◽  
Main Components ◽  
Column Pressure ◽  
Boyle’S Law ◽  
Air Column

This paper presents the design details of a simple compressible air column pressure gauge system. The main components of this pressure gauge consist of a Mariotte bottle, plastic tubing, and a graduated scale. This low-cost gauge design is based on applying the principle of Boyle’s law for gases, which makes it particularly well-suited for the measurement of soil–water characteristics of coarse-grained soils, which desaturate at a faster rate, particularly in the low matric suction range of 0–10 kPa. Among its many uses, this precise gauge is best employed in the axis translation technique to measure matric suction in the range of 0–700 kPa.

Assessment of Conversational Speech Quality Inside Vehicles, Concerning Influences of Room Acoustics and Driving Noises

2012 ◽  
Vol 98 (3) ◽  
pp. 461-474 ◽  
Author(s):  
Oliver Jung
Keyword(s):  
Transfer Functions ◽  
Strong Relationship ◽  
Speech Quality ◽  
Room Acoustics ◽  
Conversational Speech ◽  
Acoustical Parameters ◽  
Vehicle Interior ◽  
Lombard Effect ◽  
Speech Spectrum ◽  
The Impact

This study considers the influences of room acoustics and driving noises in vehicle interiors on the subjectively perceived acoustical quality of conversations between passengers. A listening test with 25 participants was performed inside a laboratory to assess the impact of different vehicle interior transfer functions on the speech quality assessment in four predetermined dimensions. Idealized driving noises at three different vehicle speeds were presented simultaneously with speech samples to quantify the interferences of these noise conditions with varied signal-to-noise ratios. To minimize the influence of different human speakers, four talkers (two male and two female) were selected from commercially available audio books. The respective speech samples were adjusted in level and long-term average speech spectrum to the common values of conversational speech. The automatic reflex of raising one's voice in noisy environments, called “Lombard Effect” [1], was taken into account for an additional adjustment of speech levels while driving noises were present. A strong relationship between the speech-to-noise ratio and the test participants' evaluations was found. Thus, one can assume that the speech signals' attenuation or amplification caused by the different room acoustics of the tested vehicles play a more important role for a sufficient speech quality than the varied speech timbre or other parameters. Only at very high speech-to-noise ratios ( ≥ 20 dB with A-weighting), room-acoustical parameters such as IACC or the reverberation time are more determining for the speech quality appreciation than the speech's sound pressure level.

On the Dynamics of Steam Liquid Heat Exchangers

1961 ◽  
Vol 83 (2) ◽  
pp. 244-251 ◽  
Author(s):  
Arvid Hempel
Keyword(s):  
Frequency Response ◽  
Heat Exchangers ◽  
Transfer Functions ◽  
Liquid Velocity ◽  
Amplitude Ratio ◽  
Analog Computer ◽  
Phase Lag ◽  
Liquid Temperature ◽  
Response Measurement ◽  
Liquid Heat

The aim of the present work has been to present relatively simple transfer functions for steam/liquid heat exchangers, relating outlet liquid temperature to variations in, respectively, the steam temperature, the liquid velocity, and the inlet liquid temperature. The transfer functions are first obtained from the partial differential equations of the system and then simplified. From the simplified expressions the transient response can readily be obtained and, in addition, they are of a form easily simulated on an analog computer. Experimental frequency response data are provided. An analog computer proved useful in analyzing phase lag and amplitude ratio in the frequency response measurement.

scholarly journals Air column of pressure hydrocyclone with pneumatic regulator

2021 ◽  
pp. 4-10
Author(s):  
Yuri Kopanytsia
Keyword(s):  
Solid Phase ◽  
Experimental Studies ◽  
Optimization Criterion ◽  
Design Parameters ◽  
Laboratory Model ◽  
Maximum Effect ◽  
Technological Parameters ◽  
Linear Character ◽  
Column Pressure ◽  
Air Column

A reliable non-contact pneumatic pressure regulator of a pressure hydrocyclone is offered. The regulator is installed in the area of ​​the sand nozzle. The pneumatic regulator of the standard pressure cylindrical-conical hydrocyclone provides non-contact thickening of the product in the area of ​​the sand nozzle. In the process of controlling the operation of the hydrocyclone along its axis, an air column is formed. Features of the regulator affect the formation of the air column of the hydrocyclone. The pressure in the air column is manometric. The task is to investigate the effect of pulp pressure at the inlet of the hydrocyclone, pulp thickening and air column pressure. Experimental studies were performed in the laboratory on a model of a standard industrial cylindrical-conical hydrocyclone HC360. The connection between the technological parameters of the hydrocyclone operation and the pressure in the air column has been studied. to establish possibilities of control of work of a hydrocyclone on pressure in an air column. The planning of the experiment in the laboratory on a hydrocyclone model was performed in the program Statgraphics Centurion XV. Experimental studies were performed for the optimal parameters of the angle and slit of the pneumatic regulator. The optimization criterion is chosen – the maximum effect of pulp thickening while minimizing local energy losses in the nozzle. In laboratory conditions, the change in pulp pressure and density at the inlet of the hydrocyclone over the entire operating range is simulated. The laboratory model of the hydrocyclone was made on a scale of M1:10. Flotation waste was used as pulp. Modeling of hydrocyclone operation as a part of water-sludge system at the concentrator is carried out. The density of the solid phase is 1500 kg/m3. The solids content at the inlet is 10 g/l. Samples were taken by volumetric measurement with a measuring vessel. A statistically significant relationship between the pressure in the air column of the hydrocyclone and the effect of pulp thickening in a standard cylindrical-conical hydrocyclone was established. The presence of the linear character of the dependence of the coefficient of thickening and pressure in the air column of the hydrocyclone with the pneumatic regulator is checked. The absence of a statistically significant effect of hydrocyclone supply pressure on the dependence of other selected factors was established. Experimental studies were carried out at the optimal design parameters of the pneumatic regulator according to the criteria of minimizing the loss of energy of air current in the nozzle and minimizing the volumetric flow of air.

Influence of Different Impulse Response Measurement Signals on MUSIC-Based Sound Source Localization

2017 ◽  
Vol 29 (1) ◽  
pp. 72-82 ◽  
Author(s):  
Takuya Suzuki ◽  
◽  
Hiroaki Otsuka ◽  
Wataru Akahori ◽  
Yoshiaki Bando ◽  
...  
Keyword(s):  
Impulse Response ◽  
Source Localization ◽  
Sound Source ◽  
Transfer Functions ◽  
Signal To Noise Ratio ◽  
Microphone Array ◽  
Sound Source Localization ◽  
Sound Sources ◽  
Response Measurement ◽  
Significant Difference

[abstFig src='/00290001/07.jpg' width='300' text='Six impulse response measurement signals' ] Two major functions, sound source localization and sound source separation, provided by robot audition open source software HARK exploit the acoustic transfer functions of a microphone array to improve the performance. The acoustic transfer functions are calculated from the measured acoustic impulse response. In the measurement, special signals such as Time Stretched Pulse (TSP) are used to improve the signal-to-noise ratio of the measurement signals. Recent studies have identified the importance of selecting a measurement signal according to the applications. In this paper, we investigate how six measurement signals – up-TSP, down-TSP, M-Series, Log-SS, NW-SS, and MN-SS – influence the performance of the MUSIC-based sound source localization provided by HARK. Experiments with simulated sounds, up to three simultaneous sound sources, demonstrate no significant difference among the six measurement signals in the MUSIC-based sound source localization.

scholarly journals Effects of bending portions of the air column on the acoustical resonances of a wind instrument

2012 ◽  
Vol 131 (5) ◽  
pp. 4164-4172 ◽  
Author(s):  
Simon Félix ◽  
Jean-Pierre Dalmont ◽  
C. J. Nederveen
Keyword(s):  
Wind Instrument ◽  
Air Column

A simple way for producing holographic filters suitable for image improvement

1978 ◽  
Vol 36 (1) ◽  
pp. 226-227
Author(s):  
K.-H. Herrmann ◽  
E. Reuber ◽  
P. Schiske
Keyword(s):  
Transfer Functions ◽  
Diffraction Order ◽  
Lateral Position ◽  
Simple Method ◽  
Spatial Frequencies ◽  
Resolution Electron ◽  
Wiener Filters ◽  
Image Improvement ◽  
Optical Reconstruction ◽  
Set Up

Aposteriori deblurring of high resolution electron micrographs of weak phase objects can be performed by holographic filters [1,2] which are arranged in the Fourier domain of a light-optical reconstruction set-up. According to the diffraction efficiency and the lateral position of the grating structure, the filters permit adjustment of the amplitudes and phases of the spatial frequencies in the image which is obtained in the first diffraction order.In the case of bright field imaging with axial illumination, the Contrast Transfer Functions (CTF) are oscillating, but real. For different imageforming conditions and several signal-to-noise ratios an extensive set of Wiener-filters should be available. A simple method of producing such filters by only photographic and mechanical means will be described here.A transparent master grating with 6.25 lines/mm and 160 mm diameter was produced by a high precision computer plotter. It is photographed through a rotating mask, plotted by a standard plotter.

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