Research On The Sound Characteristics Of Pneumatic Reed Whistles

Pneumatic reed whistle voice devices to gas for power supply, gas into the gas chamber after flowed from reed aperture, drive the vibrating reeds sound. It is characterized by simple structure, easy to operate and convenient to implement. About research and application of the reed whistle, current research is mostly about edge sound system, which is similar to the harmonica chamber single reed slit flow vibration voice and multiple reed slit air flow at the same time the characteristics of the vibration of vocal few studies. So, in this paper, numerical simulation and experimental measurement to explore reeds sound of harmonic response analysis, the strength of vibration, acoustic radiation power level, the relevant frequency, sound pressure, sound field parameters, such as for further practical application of reed whistle to lay the foundation theory and model.This paper introduces the research progress on the basis of the reed sound installations, explore the reed vibration characteristics using the theory and method of using finite element software of reed vibration modal analysis, to explore the single reed and looks piece of fixed, orthogonal symmetric fixed effects on reed vibration modal frequency; Using ANSYS finite element software further for the harmonic response analysis, observation reed frequency corresponding to the peak stress and predict its in the subsequent experiments can successfully overcome resonance, fatigue and forced vibration caused by harmful effects. In the back of the article, through the experiment, the vibration characteristic of reed acoustic measurement and data analysis, compared with the theoretical simulation results, summarizing and analyzing the sound.In this paper, the research work has the following several aspects:(1)Using the ANSYS finite element software modal analysis of the vibration of the reed. The results showed that:when reed is a certain geometric size, the reed of the inherent frequency and vibration modal frequency have little to do with reed number; Adjacent two reed voice and symmetric reeds sound and vibration and the vibration modes of a reed single voice frequency approximately same are a few errors.(2) Analyzing the reed modal by finite element software, it found that the vibration of the reed is not single transverse vibration, with the increasing of order vibration time, frequency increases gradually, the vibration modal is also becoming more complicated. Due to the small leaf thickness experiment in this paper, the vibration of the order number is more, the vibration of the reed vibration modal appears more ways. With reed number increasing, the natural frequencies of the reed almost have no change, but the vibration time, vibration modal frequency changed more.(3) In ANSYS, on the basis of modal analysis was carried out on the reeds, then its characteristics into audible harmonic response analysis, found that two reeds sound, the vibration of the maximum displacement is a half of the reeds sound, and the minimum displacement is zero. Because when the total energy be must,the more reeds, the more energy dissipation, but the reed vibration displacement is smaller, the reeds by the shear stress are lesser, and it can more overcome the strain of resonances of the reed, and the dangers of fracture.(4) Experimental study on the leaf number, inlet pressure, the installation of the reed on voice and summarize the influence of the law.Under the same parameters, the installation of different number of reeds sound fundamental frequency slightly different, two reeds sound and vibration frequency is slightly lower than the fundamental frequency, and a reed installed orthogonal voice frequency is less than the reeds on the symmetric reeds sound frequency; The total sound pressure level does not increase as the number of the reed and increase; Increase with the linear pressure, sound pressure level is not a linear increase.For three different installation way of reed analyses and compares the spectrum diagram, can be found from the figure, reed in vibration, the peak sound pressure level there are one or multiple maxima, reed issued is not a single frequency, the greater the pressure, the excitation frequency, reed, the more the greater the sound pressure level of the peak, corresponding reed vibration modal is more complex, resulting in an increased total sound pressure level.Experiment meter respectively recorded on the view of 12 different cases of sound pressure level, and then according to the acoustic pressure formula and the directivity formula, calculate the directivity value, and use the MATLAB map coordinates. Found that this experiment stimulates reed voice belongs to the low frequency sound, there’s little directivity.