Estimation of the speed of sound waves using a modular 3D printed Helmholtz resonator

A theory is presented for deriving the speed of sound and wind velocity as a function of height in the upper atmosphere from observations on the travel times of sound waves from accurately located grenades, released during rocket flight, to microphones at surveyed positions on the ground. The theory is taken to a second order of approximation, which can be utilized in practice if lower atmosphere (balloon) measurements are available. By means of the gas law and the vertical equation of motion of the atmosphere, formulae are obtained for deriving temperature, pressure and density from the speed-of-sound profile, and these also may be evaluated to a higher accuracy if lower atmosphere measurements are available. An outline is given of the computational procedure followed in the processing of data on the basis of this theory by means of the Pegasus computer. Methods of calculating the correction to travel times due to the finite wave amplitude are discussed and compared, and the effect of neglecting this correction in a particular set of experimental data is examined. Other errors which may affect the determination of pressure are also discussed. Consistency between the theory and experimental data obtained in 13 Skylark rocket flights at Woomera is checked in two ways: by examining least squares residuals associated with the sound arrivals at various microphones; and by treating the vertical component of air motion as unknown and examining its distribution about zero. The reduction in the least squares residuals which occurs when account is taken of second order terms is evaluated on the basis of these sets of experimental data.

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SOUND WAVES IN STRONGLY COUPLED NON-CONFORMAL GAUGE THEORY PLASMA

International Journal of Modern Physics A ◽

10.1142/s0217751x05029320 ◽

2005 ◽

Vol 20 (27) ◽

pp. 6298-6306 ◽

Cited By ~ 1

Author(s):

PAOLO BENINCASA

Keyword(s):

Gauge Theory ◽

Bulk Viscosity ◽

Speed Of Sound ◽

Gauge Theories ◽

Temperature Limit ◽

Sound Waves ◽

Strongly Coupled ◽

Conformal Theory ◽

High Temperature Limit ◽

Conformal Gauge

Gauge/string correspondence provides an efficient method to investigate gauge theories. In this talk we discuss the results of the paper (to appear) by P. Benincasa, A. Buchel and A. O. Starinets, where the propagation of sound waves is studied in a strongly coupled non-conformal gauge theory plasma. In particular, a prediction for the speed of sound as well as for the bulk viscosity is made for the [Formula: see text] gauge theory in the high temperature limit. As expected, the results achieved show a deviation from the speed of sound and the bulk viscosity for a conformal theory. It is pointed out that such results depend on the particular gauge theory considered.

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Determination of the propagation speed of sound waves in propane and LP gas

10.26226/morressier.5f6c5f439b74b699bf390bc1 ◽

2020 ◽

Author(s):

Niurka Chaveli Castro Chavelas ◽

Elizabeth Hernandez-Marin ◽

Gustavo Contreras-Martínez

Keyword(s):

Speed Of Sound ◽

Propagation Speed ◽

Sound Waves

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An Origami-Based Tunable Helmholtz Resonator for Noise Control: Introduction of the Concept and Preliminary Results

Volume 1: Development and Characterization of Multifunctional Materials; Mechanics and Behavior of Active Materials; Bioinspired Smart Materials and Systems; Energy Harvesting; Emerging Technologies ◽

10.1115/smasis2017-3747 ◽

2017 ◽

Author(s):

Amine Benouhiba ◽

Kanty Rabenorosoa ◽

Morvan Ouisse ◽

Nicolas Andreff

Keyword(s):

Noise Control ◽

Experimental Testing ◽

Helmholtz Resonator ◽

Experimental Tests ◽

Acoustic Control ◽

Wide Range ◽

Foldable Structures ◽

3D Printed ◽

Passive Acoustic ◽

Acoustic Domain

A Helmholtz resonator is a passive acoustic device that enables noise reduction at a given frequency. This frequency is directly related to the volume of the resonator and to the size of the neck that couples the resonator to the acoustic domain. In other words, controlling the volume of the cavity allows a real time tunability of the device, which means noise control at any desired frequency. To that end, we propose an Origami-based tunable Helmholtz resonator. The design is inspired from the well-known origami base, waterbomb. Such foldable structures offer a wide range of volume shifting which corresponds to a frequency shifting in the application of interest. The foldability of the structure is first investigated. Then, a series of numerical simulations and experimental tests were preformed are presented, in order to explore the capabilities of this origami structures in acoustic control. A shift in the frequency domain of up to 197 Hz (131–328 Hz) was achieved in an experimental testing using 3D printed rigid devices.

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Building an Instrument by Generating a Function

Open Schools Journal for Open Science ◽

10.12681/osj.24989 ◽

2020 ◽

Vol 3 (10) ◽

Author(s):

Y. Aytemiz

Keyword(s):

Water Level ◽

Longitudinal Wave ◽

Speed Of Sound ◽

Musical Instrument ◽

Sound Waves

Building a musical instrument requires precise calculations of the positions of its holes to obtain desired notes. To make these calculations, sound waves should be examined. Sound is a longitudinal wave and has five distinguishing aspects: amplitude, frequency, wavelength, period, and speed. A note is characterized by the frequency of the wave. In this experiment, the frequencies of notes and the speed of sound in air is used to calculate the length of a closed-end tube needed to obtain that frequency. Then, these values of lengths are used to create sound and the frequencies are measured with a tuner. The water level is changed until the desired frequency is reached. Then, a graph of length and 1/frequency is drawn to experimentally determine the slope, from which a function of length of tube is written in terms of frequency. With this equation, length required for any note can be calculated.

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Strong Thermal Stratification Reduces Detection Efficiency and Range of Acoustic Telemetry in a Large Freshwater Lake

10.21203/rs.3.rs-570490/v1 ◽

2021 ◽

Author(s):

Yulong Kuai ◽

Natalie Klinard ◽

Aaron Fisk ◽

Timothy Johnson ◽

Edmund Halfyard ◽

...

Keyword(s):

Great Lakes ◽

Speed Of Sound ◽

Sound Speed ◽

Acoustic Telemetry ◽

Thermal Stratification ◽

Detection Efficiency ◽

Late Summer ◽

Lake Ontario ◽

Sound Waves ◽

Detection Range

Abstract BackgroundThe successful use of acoustic telemetry to detect fish hinges on understanding the factors that control the acoustic range. The speed-of-sound in water is primarily a function of density, and in freshwater lakes density is primarily driven by temperature. The seasonal thermal stratification in the Great Lakes represent the strongest sound speed gradients in any aquatic system. Such speed-of-sound gradients can refract sound waves leading to greater divergence of acoustic signal, and hence more rapid attenuation. The changes in sound attenuation change the detection range of a telemetry array and hence influence the ability to monitor fish. We use three months of data from a sentinel array of V9 and V16 Vemco acoustic fish tags, and a record of temperature profiles to determine how changes in stratification influence acoustic range in eastern Lake Ontario. ResultWe interpret data from an acoustic telemetry array in Lake Ontario to show that changes in acoustic detection efficiency and range correlate strongly with changes in sound speed gradients due to thermal stratification. The strongest sound speed gradients of 10.38 ms-1/m crossing the thermocline occurred in late summer, which caused the sound speed difference between the top and bottom of the water column to be greater than 60 m/s. V9 tags transmitting across the thermocline could have their acoustic range reduced from >650 m to 350 m, while the more powerful V16 tags had their range reduced from >650 m to 450 m. In contrast we found that when the acoustic source and receiver were both transmitting below thermocline there was no change in range, even as the strength of sound speed gradient varied. ConclusionChanges in thermal stratification occur routinely in the Great Lakes, on timescales between months and days. The acoustic range can be reduced by as much as 50% compared to unstratified conditions when fish move across the thermocline. We recommend that researchers consider the influences of thermal stratification to acoustic telemetry when configuring receiver position.

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Thermomechanical and Photophysical Properties of Crystal-Violet-Dye/H2O Based Dissolutions via the Pulsed Laser Photoacoustic Technique

Advances in Materials Science and Engineering ◽

10.1155/2014/674719 ◽

2014 ◽

Vol 2014 ◽

pp. 1-6

Author(s):

Vicente Torres-Zúñiga ◽

Rosalba Castañeda-Guzmán ◽

Santiago J. Pérez-Ruiz ◽

Omar G. Morales-Saavedra

Keyword(s):

Crystal Violet ◽

Speed Of Sound ◽

Acoustic Waves ◽

Photophysical Properties ◽

Accurate Determination ◽

Pulsed Laser ◽

Photoacoustic Technique ◽

Sound Waves ◽

Acoustic Attenuation

Different thermoelastic parameters, for example, the acoustic attenuation and the speed of sound, are fundamental for instrumental calibration and quantitative characterization of organic-based dissolutions. In this work, these parameters as functions of the concentration of an organic dye (crystal-violet: CV) in distillated water (H2O) based dissolutions are investigated. The speed of sound was measured by the pulsed-laser photoacoustic technique (PLPA), which consists in the generation of acoustic-waves by the optical absorption of pulsed light in a given material (in this case a liquid sample). The thermally generated sound-waves traveling through a fluid are detected with two piezoelectric sensors separated by a known distance. An appropriate processing of the photoacoustic signals allows an adequate data analysis of the generated waves within the system, providing an accurate determination of the speed of sound as function of the dye-concentration. The acoustic attenuation was calculated based on the distance of the two PZT-microphones to an acoustic-source point and performing linear-fitting of the experimental data (RMS-amplitudes) as function of the dye-concentration. An important advantage of the PLPA-method is that it can be implemented with poor or null optical transmitting materials permitting the characterization of the mechanical and concentration/aggregate properties of dissolved organic compounds.

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On doubly-resonated hot-wire microphones

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character ◽

10.1098/rspa.1922.0052 ◽

1922 ◽

Vol 101 (712) ◽

pp. 391-410 ◽

Cited By ~ 2

Keyword(s):

Effective Means ◽

Helmholtz Resonator ◽

Great Sensitivity ◽

Sound Waves ◽

Hot Wire ◽

Short Neck ◽

Wire Grid ◽

Usual Manner ◽

High Degree ◽

Accurate Observation

In the selective hot-wire microphone a Helmholtz resonator is used for the detection of sound-waves of definite pitch. The resonator responds to the particular note to which it is tuned, and its response is measured by the change in resistance of an electrically heated platinum-wire grid mounted in the “neck” of the resonator. The magnitude of the response depends in the usual manner on the tuning and damping of the receiving system, and therefore in order to obtain great sensitivity the damping must be small and consequently the resonance must be sharp. For some purposes, however, sharp resonance may be a disadvantage— as, for example, when the source of sound is liable to small variations in pitch, or when allowance must be made for the Doppler effect—while at the same time it may be desired to retain a high degree of sensitivity. Even in cases where very sharp tuning is permissible, the only effective means of increasing the acoustical sensitivity is by reducing the neck of the resonator, and since this tends to expose the hot-wire grid to chance currents of air, accurate observation becomes difficult except under very favourable conditions. To meet such difficulties as these, it has been found convenient to use doubly-resonated microphones in which the hot-wire grid is placed in a short neck between two resonators, only one of which communicates directly with the outside air. In this way it is possible to increase the range of response, and at the same time to obtain greater sensitivity than is practicable with a singly-resonated microphone.

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