Browsing by Tema "Acoustics"

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Acoustic Meanings in Media Arts
(2014) Gabriela Virginia Santiago
Airborne vs. radio-transmitted vocalizations in two primates: a technical report
(Taylor & Francis, 2017) Patrice Adret; James S. Cochran; Mauricio Suarez Roda
Elucidating the structure and function of joint vocal displays (e.g. duet, chorus) recorded with a conventional microphone has proved difficult in some animals owing to the complex acoustic properties of the combined signal, a problem reminiscent of multi-speaker conversations in humans. Towards this goal, we set out to simultaneously compare air-transmitted (AT) with radio-transmitted (RT) vocalizations in one pair of humans and one pair of captive Bolivian grey titi monkeys (Plecturocebus donacophilus) all equipped with an accelerometer – or vibration transducer – closely apposed to the larynx. First, we observed no crosstalk between the two radio transmitters when subjects produced vocalizations at the same time close to each other. Second, compared with AT acoustic recordings, sound segmentation and pitch tracking of the RT signal was more accurate, particularly in a noisy and reverberating environment. Third, RT signals were less noisy than AT signals and displayed more stable amplitude regardless of distance, orientation and environment of the animal. The microphone outperformed the accelerometer with respect to sound spectral bandwidth and speech intelligibility: the sounds of RT speech were more attenuated and dampened as compared to AT speech. Importantly, we show that vocal telemetry allows reliable separation of the subjects’ voices during production of joint vocalizations, which has great potential for future applications of this technique with free-ranging animals.
Analysis of dynamic and acoustic behavior and computational verification for designing flutes
(2004) Eduardo Perilla Castillo; Álvaro Enrique Pinilla Sepúlveda
Application of the Ultrasonic Technique for Monitoring the Void Fraction in an Experimental Simulation of an Electrical Submersible Pump
(2014) Bruno Oliveira; R.D.M. Carvalho; J.L. Goncalvez; Hugo Pineda; Felicísima López; Nicolás Ratkovich
Comparative Evaluation of Grids for the Detection of Internal Defects in Concrete Using Ultrasonic Pulse Velocity: Experimental Approach
(American Society of Civil Engineers, 2025) Joaquín Humberto Aquino Rocha; Willam Murillo Borda; Marialaura Herrera Rosas; Nahúm Gamalier Cayo Chileno
This study evaluates the efficacy of ultrasonic pulse velocity (UPV) testing in detecting internal defects in concrete through an experimental comparison of various measurement grid configurations and concrete compressive strengths. Concrete blocks measuring 60×60×20 cm were fabricated with simulated internal defects created using polystyrene plates. UPV testing was performed in direct transmission mode to identify and quantify defective areas. Measurement grids with densities of 2.5×2.5 cm, 5×5 cm, and 10×10 cm were utilized, and three compressive strength levels were analyzed: 21 MPa (C21), 25 MPa (C25), and 30 MPa (C30). The findings reveal that the 2.5×2.5 cm grid is the most effective for detecting defects, offering an accurate differentiation of internal variations within the concrete, particularly in higher-strength mixtures. In contrast, less dense grids exhibited greater variability in measurements and reduced sensitivity to smaller defects (6.25 cm2). The selection of grid density should carefully balance the need for precision with practical constraints, such as time and resources. Complementing UPV testing with other nondestructive testing (NDT) methods is recommended to achieve a more comprehensive evaluation of concrete integrity.
Development of high frequency SAW devices devoted for pressure sensing
(2022) D. Vasilache; Alexandra Nicoloiu; George Boldeiu; Ioana Zdru; T. Kostopoulos; M. Nedelcu; А. Ставринидис; Claudia Nastase; Г. Ставринидис; Г. Константинидис
The paper presents a successful demonstration of 0-level packaged SAW pressure sensors developed on GaN/Si thin membranes (1.3 μ m/ 10 μ m) with a backside Mo metallization (30 nm). FEM simulations were performed in order to predict the mechanical behavior of the membrane and of the package. One-port SAW devices having IDTs of 120 nm width were fabricated bye-beam nanolithography. High values of the sensitivity (1102 kHz/Bar) and of the pressure coefficient of frequency (126 ppm/Bar) have been obtained due to the very high frequency operation (8.7 GHz) of the SAW. An insignificant dropping of these values was obtained after the bonding of the capsule.
Estudio acústico y perceptivo de la juntura en español venezolano con un corpus de pares mínimos
(2001) Elsa Mora; Christian Cavé
This paper reports an acoustical and perceptual stud y of juncture in Venezuelan Spanish. The corpus is made of pairs of minimal sentences pa irs such as (los habia/lo sab ia) which differs only by the place of the juncture. Acoustic al analysis points out two acoustic cues which could play a role in determining the place of the juncture: - a slight but significant rise of F0 from the firs t to the second vowel for CV# sentence-type whereas it remains stable for CVC# type. - a weak but significant vowel lengthening for clos ed syllables. In the perceptual experiment, subjects were able to identify the sentences with 70 percent accuracy thus, showing that these weak acoustic cue s could also be used as perceptual cues.
Global quieting of high-frequency seismic noise due to COVID-19 pandemic lockdown measures
(American Association for the Advancement of Science, 2020) Thomas Lecocq; Stephen Hicks; Koen Van Noten; Kasper van Wijk; Paula Koelemeijer; Raphaël De Plaen; Frédérick Massin; Gregor Hillers; R. E. Anthony; Maria-Theresia Apoloner
Human activity causes vibrations that propagate into the ground as high-frequency seismic waves. Measures to mitigate the coronavirus disease 2019 (COVID-19) pandemic caused widespread changes in human activity, leading to a months-long reduction in seismic noise of up to 50%. The 2020 seismic noise quiet period is the longest and most prominent global anthropogenic seismic noise reduction on record. Although the reduction is strongest at surface seismometers in populated areas, this seismic quiescence extends for many kilometers radially and hundreds of meters in depth. This quiet period provides an opportunity to detect subtle signals from subsurface seismic sources that would have been concealed in noisier times and to benchmark sources of anthropogenic noise. A strong correlation between seismic noise and independent measurements of human mobility suggests that seismology provides an absolute, real-time estimate of human activities.
High Speed Induced Flow Reciprocating Pumps
(SAGE Publishing, 1972) R. L. Creedon; J. Lobo-Guerrero; P. R. Selwood; J. D. Burton
Reciprocating pumps have been used for many years in conjunction with an air vessel or hydraulic accumulator placed between pump and discharge line, in order to control maximum cylinder pressures and to reduce the work done in overcoming friction. The air vessel and the discharge line are, in fact, capacitive and inductive components which together have some natural frequency generally different from the pump frequency. In this paper, it is shown that by matching the natural frequency of the discharge impedance to the pump frequency it is possible to obtain volumetric efficiencies of 200 per cent or more. This ‘induced flow principle’ was incorporated in a small high speed pump developed specifically to overcome the relative bulk and cost of conventional diaphragm pumps. Performance data for the new type of pump are compared with theoretical analogue computer solutions, and it appears that the induced flow principle may have a wider range of application than originally anticipated.
Human contributions to global soundscapes are less predictable than the acoustic rhythms of wildlife
(Nature Portfolio, 2025) Panu Somervuo; Tomas Roslin; Brian L. Fisher; Bess Hardwick; Deirdre Kerdraon; Dimby Raharinjanahary; Eric Tsiriniaina Rajoelison; Patrik Lauha; Lukas Griem; Petteri Lehikoinen
Inexpensive Methods for Detecting and Reproducing Substrate-Borne Vibrations: Advantages and Limitations
(Springer Nature, 2022) Rachele Nieri; Sabrina Michael; Carlos F. Pinto; Omar N. Urquizo; Heidi M. Appel; Reginald B. Cocroft
Low-cost and easily implemented anechoic acoustic chambers.
(2018) Alejandro Orrego González; Joao L. Ealo; Jhon Fernando Pazos Ospina
In this paper, the design, construction and verification of a low-cost and easy-to-install anechoic chamber are described. The chamber is constructed with affordable, local materials. The quality, according to the deviation from the inverse square law, complies with ISO 3745. The working dimensions of the chamber are 1.94 m long x 1.91 m wide x 1.84 m high. The nominal cutoff frequency is 400 Hz. The cost per square meter of the effective finished volume is 200 USD. With this design, small- and medium-sized enterprises are able to build anechoic chambers with a small investment, adding value to their products through characterization and subsequent mitigation, conditioning or amplification, as necessary, of emitted sound or noise. This study also contributes to the development and appropriation of knowledge in acoustics, a branch of physics of emerging importance in developing countries.
Nonlinear behavior of the tarka flute's distinctive sounds
(American Institute of Physics, 2016) Arnaud Gérard; Luis P. Yapu-Quispe; Sachiko Sakuma; Flavio Ghezzi; Gonzalo Marcelo Ramírez-Ávila
The Andean tarka flute generates multiphonic sounds. Using spectral techniques, we verify two distinctive musical behaviors and the nonlinear nature of the tarka. Through nonlinear time series analysis, we determine chaotic and hyperchaotic behavior. Experimentally, we observe that by increasing the blow pressure on different fingerings, peculiar changes from linear to nonlinear patterns are produced, leading ultimately to quenching.
Short-period infrasonic-noise spatial coherence
(Acoustical Society of America, 1974) José S. Flores; Alfredo H. Otero
A new method for treating the problem of infrasonic-noise spatial coherence with relation to a noise-reducing array design is developed. The behavior of this coherence at Peñas, Bolivia (4000 m above sea level), is investigated. The optimum spacing between sampling inlets for that particular location seems to be approximately 12 m at this preliminary stage of the work. The noise recorded with a two-inlet noise-reducing array at a 12-m separation was 40% less than that using only one inlet.
System of heart and lung sounds separation for store-and-forward telemedicine applications
(Universidad de Antioquia, 2012) Antonio J. Salazar; Catalina Alvarado; Fernando Enrique Lozano
Auscultation is a medical procedure that provides a general idea of heart and lung behavior as the physician listens to the breath sound. Due to the fact that the sounds from these organs overlap in time and frequency domains, important affections in one of them could be discarded. For instance, the objective of this work is to implement two different methods of cardiac and pulmonary sound separation. First, we apply modulation filters to the timefrequency representation of the original signal, recorded on the chest. Second, we apply an iterative algorithm of wavelet decomposition and reconstruction filters. Results show that they both separate signals appropriately. Taking lung signals as noise, we determine that signal to noise (SNR) ratio is 10.21 for the first method and for 6.61 the second. Applications in telemedicine are encourager since the bandwidth of the signal transmission could be reduced by sending it separately.
The Influence of Artificial Gaps in Locally Resonant Elastic Metamaterial Under Impact Loading
(RELX Group (Netherlands), 2025) Nicolás Contreras; Xihong Zhang; Hong Hao; Francisco Hernández
VIBRATION BASED RECONSTRUCTION OF THE CYLINDER PRESSURE IN DIESEL ENGINES BY USING NEURAL NETWORK
(2005) Juan Carlos Peña; Grover Zurita
The cylinder pressure curve is a very important parameter for detection of malfunctioning of combustion process in diesel engines. It provides a considerable amount of information about the performance of the engine. The traditional method to get the cylinder pressure curve is to use a cylinder pressure transducer, which is inserted in the cylinder head of the engine. This method is both expensive because of the high cost of the transducer and lifetime limited due to the harsh working environment. Therefore, there is an increasing need of a new non-intrusive method, which can be applied for the reconstruction of the cylinder pressure.The main objective of this paper is to perform the reconstruction of the cylinder pressure curve from vibration measurements by using the Neural Network Method (NNM). The cylinder pressure data obtained with transducers on operating engines was simultaneously recorded with vibration data obtained with external accelerometers at Scania Acoustic Laboratory in Stockholm (Sweden). The measured data were used to train the Neural Networks (NN), thereafter a new data set of vibration signals was enter to the NNs to get the reconstructed cylinder pressure signal. Finally, the results showed high accuracy and precision. The standard deviation of the average maximum cylinder pressures (PMax) varied between 0.03 and 1.01 percent, much lower than those obtained with other methods i.e. Cepstrum Method and Multivariate Data Analysis (MVDA). The final goal to use the NNM for optimization of the combustion process and engine diagnostics was fulfilled.