Although mode coupling occurs in acoustic pipes with nonuniform cross section, the scattering matrix can be directly obtained. Differences between cylindrical and conical brass instruments; the nonlinear propagation point of view from experiments and simulations.
The bright instruments such as the trumpet and the trombone are different from brass instruments such as saxhorns or flugelhorns. The bright instruments have a cylindrical pipe segment just downstream of the mouthpiece. The conical bore of the saxhorns implies a faster decay of the wave, which reduces the nonlinear wave steepening. In this talk, theoretical and experimental results of brassiness associated with brass instruments having different bores, from mainly cylindrical ones to mainly conical ones, will be shown.
It has, however, also been suggested that saturation of the lip opening could play a role in the timbre change. This study compares the motion of the lips at lower dynamic levels and during extremely loud playing, using a high-speed digital camera and instruments with different sizes of mouthpiece.
Curves illustrating the variation of the open lip area as a function of time at different dynamic levels are presented, together with waveforms and spectral analyses of both the radiated sound and the pressure in the mouthpiece. The results suggest that there is no qualitative change in the time-dependent behaviour of the opening area of the lips when the instrument enters the brassy regime.
Input impedance measurements of alto saxophones with a calibration error analysis. Area, McGill Univ. Initial efforts have focused on measurements of alto saxophones using a two-microphone, three-calibration tube procedure.
We first present the design of the impedance probe, as well as the data sampling and analysis procedures. We then discuss the relationship between errors in the calculated calibration parameters and the resulting measured transfer functions.
Finally, we compare the input impedances of Yamaha Z and Selmer Series II alto saxophones for several low register fingerings. We note several instances where the Yamaha saxophone possesses significantly stronger fundamental resonances than the Selmer saxophone. This 5aMU6. Interactive program for computer-aided design of woodwind presentation describes the development of an interactive computer pro- musical instruments.
The program can produce input impedance and reflection models can be incorporated into computer software, in order to evaluate function data for further acoustic analysis, and synthetic sounds that ap- not only the tuning, voicing, and other tonal characteristics of existing proximate the musical tones that can be expected form the actual instru- J.
Fricke, Fortsch. The resulting software-based version of the original Variophon, the first analog wind synthesizer using the pulse forming prin- 5aMU7. Control parameters inversion using genetic algorithms ciples, is a further step towards the intended scientific experiment system applied to numerical impedance synthesis for woodwinds. Hydroacoustics Lab, Optics and Acoust. Acoustic analyses 50 Av. Flow regimes at the output of oboe double-reeds. Christophe ance model based only on acoustical variables.
The control parameters can be re- Measurements of the quasistatic nonlinear characteristic curve for duced to a number of three including the length of the resonator, the mouth double reeds show systematic deviations from an elementary model of a pressure, and a mask parameter. In this paper we present preliminary in- reed instrument based on a spring model associated to a Bernoulli flow version results for the latter two parameters in the case of a clarinet.
The input into the reed. These deviations were previously explained by the inversion algorithm is based on differential evolution metaheuristics with a pressure recovered by the flow as it expands in the conically divergent number of prior conditions on the correlated parameters. A cost function output duct of the reed. An extension of these measurements to oscillating regimes allows us sustained part of synthesized sounds and a regularization method is pre- to observe some qualitative differences in the flow, suggesting an impor- sented to allow us to invert attack and decay parts as well as real analogi- tant influence of the dynamic terms in the Navier-Stokes equation in these cally recorded signals.
Results will be of main interest for tuning control kinds of regimes. Wolf notes in brass wind instruments. Thomas R. Moore 5aMU8. Virtual wind instruments based on pulse forming synthesis. Musicology and Psych. New data now suggest that these effects are en- pulse forming. The core of that principle is that every wind instrument hanced when the fundamental frequency of the note is near a resonance sound can basically be put down to its excitation impulses, which inde- frequency of the bell vibration.
This effect results in a situation that is pendently of the fundamental always behave according to the same prin- analogous to the wolf note commonly found on stringed instruments. Al- ciples. By controlling the pulse width and shape it is possible to generate though the physics of the process is still poorly understood, the effect all sound nuances that can be produced on a real wind instrument. Based appears not to be related to a change in impedance of the air column. AM J. Keith Wilson, Cochair U.
Army Cold Regions Research Lab. Sound field modeling in a street canyon with a diffusion equation. A diffusion equation is then derived to predict the sound field distribution and the sound decay in the street. The main parameter, namely the diffusion coefficient, is a function of the street width and the acoustic reflection laws of both building facades.
For a single rectangular street, analytical solutions can be found. For more complex urban spaces, a finite-element based approach is proposed. Several numerical examples are given, like the sound propagation in a street with a nonuniform cros section, and in street intersections, for point and line sources. In comparison with ray-tracing-based models, the diffusion model requires less computation time and could be applied to the calculation of a sound map for large urban areas.
Prediction of road traffic noise using two-dimensional numerical analysis. Design, Inc. For such road structures, an energy-based engineering model cannot be applied and noise propagation should be addressed through introduction of wave theory. Comparisons between calculations by BEM and FDM and field measurements and experiments for three actual road structures were conducted.
Consequently, calculation results agreed well with measured ones. Therefore, the validity of the calculation methods was confirmed. Modeling outdoor sound propagation in mountainous areas. Group, Dept. Pietersnieuwstraat 41, Gent, Belgium, dick.
The strong gradients in ground surface create propagation conditions that may lead to noise levels much higher than expected at some distance from the source partly due to a focusing effect. Meteorological conditions are particular: main winds following the valley, strong temperature gradients often including stable inversion, slope winds, etc. Because of these particular conditions, efficient modeling of outdoor sound propagation in mountainous area requires adaptations to be made to general purpose models.
In this paper we will present possibilities for making time-domain models terrain following and consider options to decrease the memory requirements. For the higher frequency range and distances one is generally interested in, these adaptations are insufficient. Propagation results for each slice are added.
Numerical simulations are compared to field measurements made close to an Alpine highway. Measurements of acoustic impedance and their application to sound propagation calculations and audible simulations. First, measurements using a particle velocity sensor for acoustic impedance were tested on various fields. Such measurement results were applied to calculations of sound propagation. Frequency characteristics of sound propagation were obtained along such surfaces as fields of lawns and snow, and areas paved by porous asphalt for drainage.
Those characteristics showed fair correspondence with inspected field measurement results. Then, fine calculations in the frequency domain were converted to the impulse response for each sound field model.
Convolution operations based on the impulse response and on voice, music, and some noise sources readily produced an ideal sound field to the audible sound file. Furthermore, simulations of the noise, including noise reduction effects from a car running through a drainage pavement area, were executed as advanced applications. Our measurement method of acoustic impedance is inferred to be useful. Calculated sound propagation characteristics based on the measured acoustic impedance correspond to actual propagation characteristics.
Audible simulation will be effective as a future means of sound-field evaluation. Quiet heights and pulse tails: The modal structure of near ground to near ground sound propagation in the nocturnal duct. The modes account for refraction due to sound-speed gradients as well as for the compliance and resistance of the ground.
For typical nocturnal ducts and ground surfaces one finds two types of modes: a surface mode and a set of higher modes. The surface mode is more slowly propagating and more rapidly attenuated than the higher modes.
Influence of short-term variations of meteorological parameters on sound propagation outdoors. Outdoor measurements involving roughly meteoro- logical and acoustic sensors have been carried out during 3 months in in the southwest of France.
Some longer-term effects, from days to months, are studied too. These include occurrences of meteorological configurations and variation of ground parameters. The effect of meteorological variability on sound propagation is studied using parabolic equation simulations. Comparisons between numerical predictions and experimental data will be discussed.
Effect of atmospheric absorption on aircraft noise propagation in various world regions during the year. For that 5a SAT. AM reason, it varies in response to changing meteorological conditions on a variety of time scales. To perform long-term prediction of outdoor sound propagation more accurately, it is necessary to examine the fluctuation of the attenuation coefficients for atmospheric absorption during the year.
Large variations occur according to the time and place in actual meteorological conditions, on which the attenuation coefficients depend strongly. The attenuation coefficients for atmospheric absorption were calculated from hourly meteo- rological data obtained at ten international airports throughout the world during a year using the calculation method described in ISO Calculated results show that the variability characteristics of the attenuation coefficients during the year depend strongly upon both the sonic frequency and the place.
The effects of atmospheric absorption on aircraft noise propagation were examined using the calculated attenuation coefficients. Results showed that the A-weighted sound pressure levels and sound spectra of aircraft noise vary strongly because of the changes in atmospheric absorption, which depend on actual meteorological conditions of various world regions.
Acoustic travel-time tomography of temperature and wind velocity fields in the atmosphere. Vladimir E. Army Engineer Res. In the present paper, we report on a progress in construction of a state-of-the-art array for acoustic tomography of the atmosphere, which will allow us to measure travel times of sound propagation between different pairs of sources and receivers within a few meters above the ground.
Using these travel times, the turbulent fields will then be reconstructed using different inversion algorithms. The array is being built at the Boulder Atmospheric Observatory, CO, in a collaborative effort between several organizations in the U. Furthermore, we discuss several inverse algorithms for estimation of the turbulent fields, including recently developed time-dependent stochastic inversion.
Finally, some of these algorithms were used to reconstruct temperature and wind velocity fields in indoor and outdoor tomography experiments carried out by scientists from the Institute of Meteorology, University of Leipzig, Germany. Examples of the reconstructed fields are given. A comprehensive noise study for the city of Lincoln, verify algorithms for outdoor propagation is indicated.
Bauxite refinery community noise control and prediction. The that incorporates all primary traffic arterial and readily identifiable noise Alumar refinery will expand from approximately 1. The program included noise cal location of the respondents. The results of the survey are used to refine measurement in the existing plant, development of the Bauxite Refinery the density of the test locations and the scale resolution of the software Noise Control Manual, several noise control guidelines, and noise model- model, as well as to provide city and county officials with a targeted ing to predict community noise impact.
The plant is surrounded by differ- course of action pertaining to regulations and noise abatement policies. Using computer modeling it was studied how the refinery analyzed. The paper presents the noise program results obtained by the year Effect of parameters on modeling low-frequency propagation of petrochemical plant noise over water.
Statistical models for fading and coherence of sound in Corp. Army Modeling noise is vital to designing petrochemical plants to meet com- Engineer Res. For propagation over land, there are substantial variations of actual levels from the long-term average Urban environments typically produce strong, multipath scattering. It computed using ISO Commercial modeling software based on is often desirable to characterize the effects of the scattering with statisti- ISO excludes propagation over water, where levels are often cal models for signal fading and coherence.
This paper discusses initial higher and more variable than at the same distance over land. Over water, efforts to develop such models.
Random configurations of buildings, with higher levels and variability arise primarily from wind, thermal inversions, varying sizes and number densities, are synthesized. Sound waves are then and lack of attenuations from ground clutter. Often a petrochemical plant propagated through the random configurations. The first and second mo- and receivers are separated by a large body of water, which reduces mod- ments of the sound field are calculated by averaging results from the eling accuracy.
To better understand propagation over water, full-wave random realizations. We also compare the ray tracing to finite- Plots of attenuation with distance and contours in a vertical plane are difference, time-domain calculations, which provide a full-wave solution presented for 63 Hz.
Initial results show J. The extinction and coherence decay rate increases with the number of buildings and size, but appears to 5aNS An acoustic technique for monitoring off-highway vehicle be independent of frequency. Trail counters are typically used to monitor OHV activity, but accu- racy of this technique remains relatively untested. Harris, and Teak K. Events were identified This paper presents a review on diffraction theories for highway noise in the SLM data by comparing time-history profiles collected in the field barriers.
Insertion loss based on different diffraction theories was investi- with profiles of known snowmobile passes. TMs consistently missed passes and theory, the average difference of insertion loss between TNM and overestimated events compared to SLMs. To improve the prediction be more sensitive and reliable detectors of OHV activity.
These results accuracy of TNM, it is recommended that the MacDonald solution, but have implications in both wildlife research and land management applica- with real and image sources, should be deployed. Garrett, Cochair Pennsylvania State Univ. We found that the amplification rate was essentially deter- 5aPA1. Amplification of acoustic intensity of a pulse wave mined by the ratio of thermal boundary layer thickness to the pore radius propagating through a tube having a temperature gradient.
Tetsushi of the regenerator. Design, Tohoku Univ. Pattern formation in thermoacoustic resonators. German J. Even though he only observed damping of the acoustic 5a SAT.
AM intensity in the experiment, his idea serves as a starting point of new The phenomenon of pattern formation is ubiquitous in the dynamics of acoustic devices known as thermoacoustic Stirling heat engines.
For a extended nonlinear systems. Patterns arise from the interplay of external further progress of the thermoacoustic technology, experimental verifica- forcing, dissipation, nonlinearity, and spatial coupling. These factors are tion of his idea is of great importance.
In this paper, we report on the also present in many acoustic systems. However, under usual conditions thermoacoustic amplification of acoustic intensity using pulse waves trav- where the elastic nonlinearity dominates, the development of shock fronts eling in a long tube equipped with a differentially heated regenerator.
A in nonlinear regime strongly limits the possibility of a simple analysis. A series of pressure transducers was used to determine the axial acoustic systems presenting patterns with similar characteristics as those distribution of the acoustic intensity.
Use of a pulse wave enabled us to see found in other fields, such as hydrodynamics or optics. A model describing J.
An idea of the method of renormalization enables us to obtain plane walls containing a viscous medium is presented. The large aspect analytical solutions and to derive the marginal condition when the tem- ratio of the resonator allows the transverse spatial coupling, mediated by perature distribution is parabolic. Solving the condition numerically, the sound diffraction and temperature diffusion. The homogeneous solutions marginal curve for the temperature ratio is displayed graphically against show bistability at some values of the parameters, in agreement with ex- the tube radius relative to the boundary-layer thickness.
It is found that the perimental results reported in the bibliography. We show by means of temperature ratio has a minimum and that the curve has two branches with linear stability analysis that the homogeneous solutions develop spatial respect to the minimum. While the left branch for viscous mode extends to instabilities leading to the spontaneous generation of spatial patterns.
The infinity, the right branch, close to the curve for neutral oscillations, asymp- analytical predictions are confirmed by a numerical analysis. Spatial mode of oscillations is also displayed in the marginal state and some discussions on the energy balance are included. Anharmonic acoustic resonators in miniature thermoacoustic cooler. El-Gendy, L. Lyard, and O. Direct observation of thermoacoustic energy conversion.
A gas column starts to oscillate when the externally imposed tempera- To overcome this limitation, noncylindrical resonators were studied here. Also, when an acoustic wave propa- Conical, exponential, and halfcosine shapes were used. They produce gates through a differentially heated regenerator, the acoustic intensity is high-amplitude sound waves with essentially no shock waves. Such reso- thermally amplified. Such thermoacoustic phenomena attract considerable nators were chosen here to operate at around 4 kHz, the resonant fre- interest not only because it becomes possible to develop pistonless Stirling quency of the piezoelectric driver.
They are easily adapted to the miniature heat engines, but because an alternative approach to understand a heat refrigerator. Moreover, they provide an impedance match, which is shape engine has been proposed based on energy flows.
In this work, we report dependent, between the driver and the resonator. Tests at sound intensity the direct observation of the thermoacoustic energy conversion in a tube levels up to dB show essentially no distortion of the acoustic wave- filled with atmospheric air to test the validity of the proposal. A gas col- form. Results of their performance will be discussed. We simultaneously measured pressure and velocity oscillations to determine the acoustic intensity. As a result, we found the amplification of acoustic intensity in the region with a positive temperature gradient.
This 5aPA4. A study for applying lower temperature heat source to supports the proposed approach. Further test was made by comparing the loop-tube thermoacoustic cooling system.
It is known that the existence of dc flow acts as the negative effect for the loop-tube. The membrane re- duces a loss of thermal energy supplied to the prime mover by suppressing the dc flow.
So it is considered that lower temperature difference between 5aPA7. Study on a thermoacoustic cooling system to drive the both the edges of the stack can be realized by using presented system. The fundamental resonance frequency by connecting a triggered tube. The experiments were carried out Labs. It was found that the temperature difference is affected by the position of the membrane.
When the membrane was set at the approximate A thermoacoustic cooling system to drive a looped-tube with the fun- antinode of pressure, the lowest temperature difference was realized. In damental resonance frequency by connecting a triggered tube is proposed.
The existence of dc flows, which was K lower than without the membrane. These results suggest which is caused by harmonics in the looped tube, has been pointed out as that a lower temperature heat source can be available by setting the mem- negative effects.
The presented thermoacoustic cooling system, however, brane on the loop-tube thermoacoustic cooling system. It is well known that the phase relation between sound pressure and particle velocity is important, 5aPA5. Marginal instability of thermoacoustic oscillations of a gas in and approximately in-phase relation is the best position for cooling effect.
In the presented system, the sound energy is supplied from the looped Sci. School of Eng. It is important to know the best connecting position where the phase Japan, sugimoto me. The sound pressures were observed, then the phase relations were calculated by two-sensor power method. By This paper examines a marginal condition of instability of thermoa- using results, the best position of the triggered tube was decided.
It is coustic oscillations of a gas in a tube with one end open and the other confirmed that the presented system can realize the suppression of har- closed by a flat wall, subjected to a smooth temperature distribution axi- monics and the decrease of outlet temperature. It is also confirmed that the ally. Assuming a boundary layer is thin compared with the tube radius, the decrease of temperature has the higher effects compared with the looped linear theory is developed in the framework of the first-order theory in its tube in the same environmental conditions.
Determination of complex propagation constant, acoustic intensity, and acoustic power in an arbitrarily terminated pipe using laser Doppler anemometry. Ki Won Jung and Anthony A. Program in Acoust. Resonant aero-acoustic excitation of cavity depth modes.
Efimtsov, Alexey Yu. It is less common to use measurements of acoustic particle Results are generalized of parametric experimental investigations of velocity for the same purpose. Spe- though this measurement technique requires optical access to the region of cial attention is given to the fundamental mechanisms responsible for this interest and the use of seeding particles, in some circumstances it can be phenomenon.
The conditions for these mechanisms to manifest themselves less invasive and offer greater flexibility than measuring pressure fields and interact are predicted. Observations are made of the relations between with microphones. The focus of this research is to use LDA to determine the characteristic flow and cavity parameters at which the maximum reso- the complex propagation constant, acoustic intensity, and power inside a nant aero-acoustic response of the cavity depth mode takes place.
These constant cross-section circular pipe. The measured particle velocities are relations take into account the distinction between the flow velocity and fit to a counterpropagating plane-wave model to determine the complex the characteristic spreading velocity of the disturbances downstream of the amplitudes and propagation constant.
Other acoustic quantities, such as wall discontinuity as well as the distinction between the cavity depth and the radial-dependent acoustic intensity and the cross-sectional-averaged the characteristic linear scale in the Helmholtz number connected with the acoustic power, can then be calculated.
The complex propagation constant edge effect for sound waves in the vicinity of the cavity gap. Experimental is compared with the theoretical value based on thermoviscous boundary data illustrating the reliability of these relations are presented. The extent layer theory. Graduate Program in Acoustics. Single transducer parametric sound source. Spectral gaps and discrete transmission in slender tubes.
Manvir S. Box J, The idea of using the nonlinear effects of the propagation of sound Puebla, Pue. Akjouj, B. Djafari-Rouhani, L. In underwater acoustics, such parametric arrays are widely used. There are also attempts to build up parametric arrays in air to gen- Extensive band structure and transmission spectra for the longitudinal erate highly directed air-borne sound.
The emphasis is laid on the directivity, of the sound source as well as the acheived sound pressure interesting result of huge gaps and discrete transmission spectrum due level. It is difficult to investigate basic properties of wave propa- an entirely discrete band structure and transmission spectrum. This should gation and the nature of distortion in such a way. In this work, a single, have important consequences for the suppression of low-frequency noise high-power ultrasound transducer was used to radiate sound waves with and for designing filters and transducers.
Using only a single transducer, it was possible to investigate basic prop- erties of nonlinear wave propagation in air. The effects of turbulence on an undular bore. Pablo Luis 5aPA Scale model experiments over curved rough surfaces. Wednesday 28 July Thursday 29 July Friday 30 July Saturday 31 July Sunday 1 August Monday 2 August Tuesday 3 August Wednesday 4 August Thursday 5 August Friday 6 August Saturday 7 August Sunday 8 August Monday 9 August Tuesday 10 August Wednesday 11 August Thursday 12 August Friday 13 August Saturday 14 August Sunday 15 August Monday 16 August Tuesday 17 August Wednesday 18 August Thursday 19 August Friday 20 August Saturday 21 August Sunday 22 August Monday 23 August Tuesday 24 August Wednesday 25 August Thursday 26 August Friday 27 August Saturday 28 August Sunday 29 August Monday 30 August Tuesday 31 August Wednesday 1 September Thursday 2 September Friday 3 September Saturday 4 September Sunday 5 September Monday 6 September Tuesday 7 September Wednesday 8 September Thursday 9 September Friday 10 September Saturday 11 September Sunday 12 September Monday 13 September Tuesday 14 September Wednesday 15 September Thursday 16 September Friday 17 September Saturday 18 September Sunday 19 September Review: Not much is known about Ueno Masaaki other than he's a Japanese artist that's debuting on Raster-Noton with a burgeoning new sound.
It's a cutting edge sound that fits in perfectly with demeanour of Raster-Noton and all tracks on Vortices sound like dry, micro-loop reductions of Aoki Takamasa's music. Masaaki's inclusion to the label's Unun series follows previous releases by Mika Vainio and Emptyset - and if that's who label founder Byetone wishes to associate the Japanese artist with than we can expect great things in the future. R-N 22 Sep 14 Techno. See all Downloads. See all Genre. Friday 17 September Saturday 18 September Sunday 19 September Monday 20 September Tuesday 21 September Wednesday 22 September Thursday 23 September Friday 24 September Saturday 25 September Sunday 26 September Monday 27 September Tuesday 28 September Wednesday 29 September Thursday 30 September Friday 1 October Saturday 2 October Sunday 3 October Monday 4 October Tuesday 5 October Wednesday 6 October Thursday 7 October Friday 8 October Saturday 9 October Sunday 10 October Monday 11 October Tuesday 12 October Wednesday 13 October Thursday 14 October Friday 15 October Saturday 16 October Sunday 17 October Monday 18 October Tuesday 19 October Wednesday 20 October Thursday 21 October Friday 22 October Saturday 23 October Sunday 24 October Monday 25 October Tuesday 26 October Wednesday 27 October Thursday 28 October Friday 29 October Saturday 30 October Sunday 31 October Monday 1 November Tuesday 2 November Wednesday 3 November Thursday 4 November Friday 5 November Saturday 6 November Sunday 7 November Monday 8 November
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