Sound Speed In Air Research Articles

Instantaneous Measurement of the Speed of Sound in Air and Water Using Arduino

Although schools commonly teach that sound waves propagate faster in solids than in liquids and in liquids than in gases, there is no low-cost activity that allows students to investigate if this statement is true or not. Indeed, some existing techniques simply allow them to identify the speed of sound in air and its temperature dependence.

Determining the Dependence of the Speed of Sound in Air on Air Temperature Based on Properties of Standing Waves

Standing waves are a naturally arising phenomenon in many situations where sound waves propagate in an enclosed medium. Inspired by problem 17 from the International Young Naturalists Tournament (2021), this investigation aims to establish a relationship between the speed of sound in air as a function of air temperature at constant pressure and humidity. This goal is achieved by exploiting certain properties of standing sound waves in a tube, sealed off at one end. By varying the length of the tube and the temperature of the air inside, properties of the air, such as its molar mass, can also be determined.

An Arduino Investigation of the Temperature Dependence of the Speed of Sound in Air

The determination of the speed of sound in air is a classical experiment, usually performed with a resonance tube apparatus. The measured value can be checked against Eq. (1), which describes the temperature dependence of the speed of sound in dry air. A modern implementation of this speed of sound investigation uses an Arduino Uno microcontroller board, an HC-SR04 ultrasonic distance sensor, and a DS18B20 temperature sensor. The distance sensor’s transmitter produces a burst of eight ultrasonic rectangular pulses that travel through the air, reflect on an object placed in front at a distance d, and then return to the sensor’s receiver after an echo time t. This Arduino investigation, unfortunately, is harder to perform than one might expect after a first reading of Ref. 1 or 2. In this article we discuss some sources of experimental errors that can complicate this laboratory activity, and we describe some important steps that must be included in the data collection and analysis procedure, in order to obtain successful results every time.

ЗОВНІШНЯ БАЛІСТИКА СНАРЯДУ БМ1 ВИПУЩЕНОГО З Т-12 (МТ-12)

The magnitudes of the kinematic parameters of projectiles motion in the air depends on deterministic (form of projectile, its mass, temperature of air and charge, atmospheric pressure, derivation) and nondeterministic (muzzle velocity, magnitude and direction of wind velocity) values. During the projectile movement, its weight and frontal air resistance force have a determining influence on its dynamics. In the article it is investigated proposed by authors the mathematical model of determination of the functional dependence of the magnitude of the frontal air resistance force of the projectile’s motion on its velocity, mass and caliber, geometric characteristics, temperature and density of air, atmospheric pressure, sound speed in air. Since the trajectory of movement of the BM1 projectile released from the T-12 (MT-12) is canopy, it is assumed that during the projectile’s flight the air temperature and atmospheric pressure are unchanged and equal to their value at the point of the gun.

High bandwidth airborne acoustic detection system (HBADS) for circular synthetic aperture acoustic imaging of canonical ground targets

High Bandwidth Acoustic Detection System (HBADS) is an active acoustic sensor technology developed by the US Army’s Night Vision and Electronic Sensors Directorate. The stripmap airborne synthetic aperture acoustic (SAA) array (mounted on an all-terrane vehicle) contains two horizontal rows of eight evenly spaced microphones oriented in a side scan configuration. An audio speaker (located near the array center) transmits a linear FM chirp having a 2 kHz to 15 kHz effective bandwidth. Experiments are performed with the vehicle in motion to image canonical ground targets in clutter or foliage. A laptop computer controls the 16 channel data acquisition system. The system includes an inertial navigation system (two differential GPS antennas), a wheel coder, a camera, and a unit for measuring temperature, pressure, and humidity. Experiments include imaging spherical targets located on the ground in a grassy field and similar targets camouflaged by natural vegetation along the roadside using both stripmap SAR and circular path C-SAR radar-like configurations. Typical parameters are chirp pulse = 10 or 40 ms, slant range resolution c/(2*BW) = 1.3 cm (air sound speed c ≈ 340 m/s), microphone diameter D = 2 cm, (azimuthal resolution is D/2), and maximum vehicle speed ≈ 2 m/s.High Bandwidth Acoustic Detection System (HBADS) is an active acoustic sensor technology developed by the US Army’s Night Vision and Electronic Sensors Directorate. The stripmap airborne synthetic aperture acoustic (SAA) array (mounted on an all-terrane vehicle) contains two horizontal rows of eight evenly spaced microphones oriented in a side scan configuration. An audio speaker (located near the array center) transmits a linear FM chirp having a 2 kHz to 15 kHz effective bandwidth. Experiments are performed with the vehicle in motion to image canonical ground targets in clutter or foliage. A laptop computer controls the 16 channel data acquisition system. The system includes an inertial navigation system (two differential GPS antennas), a wheel coder, a camera, and a unit for measuring temperature, pressure, and humidity. Experiments include imaging spherical targets located on the ground in a grassy field and similar targets camouflaged by natural vegetation along the roadside using both stripmap SAR a...

Determining the Speed of Sound as a Function of Temperature Using Arduino

When sound waves are taught at the secondary level, the speed of propagation of sound is one of the most important characteristics to be analyzed. However, it is very common in textbooks that the value of sound speed in air is considered constant regardless of the experimental conditions. The great question is that since sound is a mechanical wave, its speed is influenced by the medium of propagation and also by the temperature. In most cases, the techniques reported for that goal usually make use of expensive equipment and techniques that may not be affordable and/or easy to implement in schools, which is an experimental limitation for the teachers to show this influence on their students. In this work, we present a low-cost experimental apparatus, controlled by the open source electronic platform Arduino®, with which it is possible to determine the speed of propagation of sound as a function of the temperature for a short measuring region, thus enabling the students to verify experimentally this important feature of sound waves.

Violent flows in aqueous foams III: physical multi-phase model comparison with aqueous foam shock tube experiments

Mitigation of blast waves in aqueous foams is a problem that has a strong dependence on multi-phase effects. Here, a simplified model is developed from the previous articles treating violent flows (D’Alesio et al. in Eur J Mech B Fluids 54:105–124, 2015; Faure and Ghidaglia in Eur J Mech B Fluids 30:341–359, 2011) to capture the essential phenomena. The key is to have two fluids with separate velocities to represent the liquid and gas phases. This allows for the interaction between the two phases, which may include terms for drag, heat transfer, mass transfer due to phase change, added mass effects, to be included explicitly in the model. A good test for the proposed model is provided by two experimental data sets that use a specially designed shock tube. The first experiment has a test section filled with spray droplets, and the second has a range of aqueous foams in the test section. A substantial attenuation of the shock wave is seen in both cases, but a large difference is observed in the sound speeds. The droplets cause no observable change from the air sound speed, while the foams have a reduced sound speed of approximately 50–75 $$\hbox {m}/\hbox {s}$$ . In the model given here, an added mass term is introduced in the governing equations to capture the low sound speed. The match between simulation and experiment is found to be satisfactory for both droplets and the foam. This is especially good when considering the complexity of the physics and the effects that are unaccounted for, such as three-dimensionality and droplet atomisation. The resulting statistics illuminate the processes occurring in such flows.

Experimental realization of acoustic double zero index metamaterials

Acoustic double zero index metamaterial with simultaneous zero density and infinite bulk modulus induced by Dirac cone at the Brillouin zone center provide a practical solution for applications. The resulted finite impedance of this metamaterial can be designed to match with surrounding materials. However, such metamaterial consists of scatterers with lower sound speed than the matrix, which is fundamentally challenging for air acoustics because the sound speed in air is among the lowest in nature. Here, we experimentally realize double zero index metamaterial by periodically varying waveguide thickness, which modulates the speed sound of high order waveguide mode. With proper designed dimensions of the scatterers, a Dirac cone at 18.7 kHz formed by the degeneracy of one monopolar and two dipolar modes at the Brillouin zone center is obtain. The monopolar mode modulates the bulk modulus and the dipolar modes modulate the density, resulting in simultaneous zero density and infinite bulk modulus. In our exp...

Processing of aircraft signatures with significant Doppler, simultaneously observed on microphones and distributed underwater sensors

An experiment was performed with a source mounted on an aircraft with a microphone array rigidly mounted on a research vessel, and with sonobuoys and a vertical line array deployed in the ocean underneath. Programmed waveforms, including tones, linearly frequency modulated tones, and m-sequences, were transmitted from the airplane. The Doppler in this configuration was substantial, due to the sound speed in air being 1/5 that of water, with much of the acoustic path passing through the air. We will present results of matched filtering the transmitted waveforms, using various combinations of observed signals, including using replicas augmented by modeling, to compensate for the Doppler in order to enhance the coherent integration gain in this configuration.

Incipient electric field determination for bush and streamer stage in dielectric liquid under energy balance condition

This paper introduces a new approach for streamer advance mechanism in dielectric liquid. The existing of bush-like streamer shape early and then a tree structure shape after that has been given an over view and definition by devising a breakdown index for dielectric liquid which reach a value of 25. The deviation of streamer velocity from low values of tens of meter per second, until several kilometer per second from bush-like shape, until complete breakdown has been discussed too. These different stages have been studied on an energy balance concepts. In this paper using energy balance analysis, different critical applied fields have been obtained. These values reach 2.18 MV/cm for one branch channel in bush-like streamer shape and 21.5 MV/cm, for tree streamer. After that, the initial streamer velocities concerning these stages have been introduced. From these analysis the dissociation of dielectric liquids starts when the streamer velocity reach the sound speed in air, 331 m/s. In addition, the dissociation field depends mainly on the physical values of the dielectric medium, such as density, and permittivity have been introduced. In this paper the dissociation starts at an electric field value of 21.5 MV/cm for nearly all dielectric liquids, This result is equal to tree streamer inception value, which can be considered as a new introduced finding. A new energy equation relating injected energy electric field, velocity and new deduced breakdown index in dielectric liquid has been devised. The streamer may stop or continue its advance until complete breakdown. According to many published data for streamer, there is no clear explanation for streamer stopping and continuing it advance. In this paper, the streamer must advance ahead of the bush zone in the gap toward the opposite electrode when the prospective electric field at 66% of the gap achieves a breakdown index of 25. This result can be considered as a new criterion for streamer growth until crossing the gap. These new equations and findings have been applied to several experimental works and achieve good results.

An Inexpensive and Versatile Version of Kundt's Tube for Measuring the Speed of Sound in Air

Experiments that measure the speed of sound in air are common in high schools and colleges. In the Kundt's tube experiment, a horizontal air column is adjusted until a resonance mode is achieved for a specific frequency of sound. When this happens, the cork dust in the tube is disturbed at the displacement antinode regions. The location of the displacement antinodes enables the measurement of the wavelength of the sound that is being used. This paper describes a design that uses a speaker instead of the traditional aluminum rod as the sound source. This allows the use of multiple sound frequencies that yield a much more accurate speed of sound in air.

Passive acoustic measurements of wind velocity and sound speed in air.

Random acoustic fields generated by uncorrelated sources in moving media contain information about the propagation environment, including sound speed and flow velocity. This information can be recovered by noise interferometry. Here interferometric techniques are applied to road traffic noise. Acoustic travel times and their nonreciprocity are retrieved from two-point cross-correlation functions of noise. The feasibility of passive acoustic measurements of wind velocity using diffuse noise is experimentally demonstrated for the first time. The accuracy of the interferometric measurements of sound speed and wind velocity is confirmed by comparison with in situ measurements of wind, air temperature, and humidity.

Modeling Aspects of Sound Speed in Air for Ultrasonic Industrial Applications

In general, the sound speed in air depends on the air characteristics, such as temperature, pressure, humidity, gas composition, and air turbulence. It has direct influence on performance of ultrasonic sensing applications, like those based on the distance measuring and the sound wavelength. For many industrial applications, the sound speed in air is considered as constant, but this is true only for constant environment properties, like indoor environments with air-conditioning systems. Even then, the speed of sound can have different constant values for different sets of environment properties, generated by their spatial or temporal variations. For outdoor environments, the supposition of constant sound speed can generate important errors of distance estimation, In addition, for low temperature values, the real distance to an object is smaller than measured distance by ultrasonic sensing, and this can be a dangerous situation. Hence, simple and accurate models of sound speed in air are very important for ultrasonic industrial applications. In this paper, models of sound speed in air are studied, and new models are proposed, which are capable of dealing with uncertainties generated by unknown air characteristics. In addition, expert rules for model selection are generated, and comparative simulation results are presented.

A comparative study of sound speed in air at room temperature between a pressure sensor and a sound sensor

This paper deals with the comparison of sound speed measurements in air using two types of sensor that are widely employed in physics and engineering education, namely a pressure sensor and a sound sensor. A computer-based laboratory with pressure and sound sensors was used to carry out measurements of air through a 60 ml syringe. The fast Fourier transform (FFT) was used to find the fundamental frequency of the air column in the syringe, which can be used to calculate the sound speed for the sound sensor case. Meanwhile, for the pressure sensor case the time interval between the first peak and the nth peak of the periodic variation in pressure due to the sound wave travelling up and down the syringe was determined. The obtained average values of the sound velocity in air for the pressure sensor and the sound sensor were 340.9±3 m s−1 and 346.7 ± 3 m s−1, with errors of 0.6% and 1.1%, respectively, compared to the accepted value of 343 m s−1 at room temperature.

Time-of-flight measurement of sound speed in air

This paper describes a set of simple experiments with a very low cost using a notebook as ameasuring instrument without external hardware. The major purpose is to providedemonstration experiments for schools with very low budgets.

Acoustic tomographic imaging of temperature and flow fields in air

Acoustic travel-time tomography is a remote sensing technique that uses the dependence of sound speed in air on temperature and wind speed along the sound propagation path. Travel-time measurements of acoustic signals between several sound sources and receivers travelling along different paths through a measuring area give information on the spatial distribution of temperature and flow fields within the area. After a separation of the two influences, distributions of temperature and flow can be reconstructed using inverse algorithms. As a remote sensing method, one advantage of acoustic travel-time tomography is its ability to measure temperature and flow field quantities without disturbing the area under investigation due to insertion of sensors. Furthermore, the two quantities—temperature and flow velocity—can be recorded simultaneously with this measurement method. In this paper, an acoustic tomographic measurement system is introduced which is capable of resolving three-dimensional distributions of temperature and flow fields in air within a certain volume (1.3 m × 1.0 m × 1.2 m) using 16 acoustic transmitter–receiver pairs. First, algorithms for the 3D reconstruction of distributions from line-integrated measurements are presented. Moreover, a measuring apparatus is introduced which is suited for educational purposes, for demonstration of the method as well as for indoor investigations. Example measurements within a low-speed wind tunnel with different incident flow situations (e.g. behind bluff bodies) using this system are shown. Visualizations of the flow illustrate the plausibility of the tomographically reconstructed flow structures. Furthermore, alternative individual measurement methods for temperature and flow speed provide comparable results.

Computer Measurement of the Speed of Sound in Air(My Idea)

Computer Measurement of the Speed of Sound in Air(My Idea)

A new measurement method for ultrasonic surface roughness measurements

This study proposes the application of Doppler-based ultrasonic method to surface roughness measurements. The fabricated prototype measures the slope of the under-test surface at small holes to evaluate the roughing parameters and this makes for more precise measurement. The device comprises an ultrasonic transmitter emits sound pulses that travel across to the under-test surface. The reflected wave is separated into many weak sounds, a few of which are received by the receiver. The Doppler effect caused the frequency of the received wave to be shifted with respect to the surface roughness at the reflecting point. The relationship between the Doppler shift and the roughing slope is mathematically analyzed. Compared to the transit-time based techniques, the dependency of the sensor on the sound speed in air is decreased by a factor of 2 and therefore a more precise measurement is achieved. The fabrication of a prototype device and experimental verification of the analytical results are reported.

Low-altitude airbursts and the impact threat

Abstract We present CTH simulations of airbursts in the Earth's lower atmosphere from hypervelocity asteroid impacts. The intent of these simulations was to explore the phenomenology associated with low-altitude airbursts, with the particular goal of determining whether the altitude of maximum energy deposition can be used as a reasonable estimate of the equivalent height of a point source explosion. Our simulations suggest that this is not a good approximation. The center of mass of an exploding projectile is transported downward in the form of a high-temperature jet of expanding gas. The jet descends by a significant fraction of the burst altitude before its velocity becomes subsonic. The time scale of this descent is similar to the time scale of the explosion itself, so the jet simultaneously couples its kinetic energy and its internal energy to the atmosphere. Because of this downward flow, larger blast waves and stronger thermal radiation pulses are felt at the surface than would be predicted by a point source explosion at the height where the burst was initiated. For impacts with a kinetic energy above some threshold, the hot jet of vaporized projectile (the descending “fireball”) makes contact with the Earth's surface, where it expands radially. During the time of radial expansion, the fireball can maintain temperatures well above the melting temperature of silicate minerals, and its radial velocity can exceed the sound speed in air. We suggest that the surface materials can ablate by radiative/convective melting under these conditions, and then quench rapidly to form glass after the fireball cools and recedes. Possible examples of such airburst glasses are the Muong-Nong Tektites of Southeast Asia and the Libyan Desert Glass of western Egypt. We suggest an enhancement of entry dynamics models to account for the downward advection of shocked and heated material, and the lowering of the apparent airburst altitude. The actual differences between the effects on the ground from a point source approximation versus a full flow field still need to be quantified by running more realistic high-resolution 3-D simulations with a variety of impact parameters. A re-evaluation of the impact hazard is necessary to properly include this enhanced damage potential of low-altitude airbursts.

Measurement of the frequency and the temperature dependence of the sound speed in air by using the Lissajous curves

We have designed a simple experiment to measure the frequency and the temperature dependence of the speed of sound in air by using the Lissajous Curve for undergraduate laboratory. The speed of sound was measured in air by using the Lissajous curves and the value, 344.3 m/s was good agreement with theory under the condition of temperature, 20.4 . There was no frequency dependence between the °C frequencies, 0.4 ~ 2.0 kHz but temperature dependence of the speed of sound in air. This experimental activity would be a helpful learning materials for in-depth understanding concepts of superposition and propagation of sound waves for scientifically gifted students and undergraduate students. keywords: speed of sound, sound wave, Lissajous curves, undergraduate laboratory 그림 공기 중에서 전파하는 소리의 진행속력과 온도의 관계 4. . 실선은 이론값이며 점선은 오차 범위가 범위에서 이론값 1.5 % 과 일치함을 보여준다. 리사주 도형을 이용하여 공기 중에서 진행하는 소리의 속력 측정하기