Microphone Research Articles

Low-frequency Resonant Photoacoustic Gas Sensor by Employing Hollow Core Fiber-Based O-Shaped Multipass Cells.

A low-frequency flexible resonant photoacoustic (PA) gas sensor using an O-shaped multipass cell is demonstrated. The PA sensor employed a flexible gradually tapered leaky hollow core fiber (LHCF). The LHCF was bent to be an end-to-end structure to make full use of the incident light. Additionally, the two ends of the LHCF were put inside a single buffer chamber, yielding an equivalent H-type acoustic resonator. The geometric size was reduced thanks to the bending structure. The geometric length of the LHCF was 500 mm. A micro-electro-mechanical-systems electrical microphone was installed at the center of the resonant tube to detect the PA signal. The proposed PA gas sensor exhibited a first-order longitudinal resonance frequency of 408 Hz. Trace acetylene (C2H2) was used as the target gas. The minimum detectable limit was calculated to be 25.8 parts-per-billion (ppb) with an average time of 400 s, which was 1.93 times higher than that of a single-pass PA gas sensor. The normalized noise-equivalent absorption coefficient and the PA cell constant were calculated to be 9.6 × 10-9 W·cm-1·Hz-1/2 and 8295 Pa/W·cm-1, respectively. The PA gas sensor owns a low resonance frequency and can be used for detection of most of the polar gaseous molecules, especially suitable for gas molecules with a long V-T relation time, such as carbon monoxide and carbon dioxide.

The sound of geological targets on Mars from the absolute intensity of laser-induced sparks shock waves

Inspection of geological material is one of the main goals of the Perseverance rover during its journey across the landscape of the Jezero crater in Mars. NASA's rover integrates SuperCam, an instrument capable of performing standoff characterization of samples using a variety of techniques. Among those tools, SuperCam can perform laser-induced breakdown spectroscopy (LIBS) studies to elucidate the chemical composition of the targets of interest. Data from optical spectroscopy can be supplemented by simultaneously-produced laser-produced plasma acoustics in order to expand the information acquired from the probed rocks thanks to the SuperCam's microphone (MIC) as it can be synchronized with the LIBS laser. Herein, we report cover results from LIBS and MIC during Perseverance's first 380 sols on the Martian surface. We study the correlation between both recorded signals, considering the main intrasample and environmental sources of variation for each technique, to understand their behavior and how they can be interpreted together towards complimenting LIBS with acoustics. We find that louder and more stable acoustic signals are recorded from rock with compact surfaces, i.e., low presence loose particulate material, and harder mineral phases in their composition. Reported results constitute the first description of the evolution of the intensity in the time domain of shockwaves from laser-produced plasmas on geological targets recorded in Mars. These signals are expected contain physicochemical signatures pertaining to the inspected sampling positions. As the dependence of the acoustic signal recorded on the sample composition, provided by LIBS, is unveiled, the sound from sparks become a powerful tool for the identification of mineral phases with similar optical emission spectra.

Skin Acceleration Levels Estimated by a Neck-surface Accelerometer during Phonation Are Affected by The Mechanical Properties of The Anterior Cervical Skin

The aim of the present study was to assess whether skin acceleration levels (SAL) estimated by a neck-surface accelerometer (ACC) are affected by the anterior neck skin condition. Each of six healthy non-dysphonic participants wore a headset microphone (MIC), had an ACC sensor fitted on the skin over the cervical trachea, and were subsequently asked to gradually increase the vocal loudness during sustained phonation of the vowel /e:/ (crescendo task), while the sound pressure levels on a sound level meter (SPLSLM) and MIC/ACC signals were simultaneously recorded. Root mean squared values were calculated from the MIC and ACC signals as the sound pressure level (SPLMIC) and SAL, respectively, and the relationships between SPLSLM and SAL were compared between neck anteflexion and retroflexion or between outward and inward skin retraction on both sides of the sensor. In the total samples for the successful crescendo performance in a natural head position, the SPLMIC and SPLSLM showed a strong linear correlation (r=0.980), whereas the correlation between the SAL and SPLSLM showed a distorted regression line (r=0.765) with individual differences. In all participants, the anteflexion and inward skin retraction decreased the SAL value at the same SPLSLM value, whereas the retroflexion increased the SAL value at the same SPLSLM value. These results demonstrate that the signal intensity of a neck-surface ACC is affected by the condition of the anterior cervical skin, perhaps leading to inter-individual variability in SAL measurements.

An Automatic Gain Control Circuits for the Microphone Read-out Integrated Circuit

An Automatic Gain Control Circuits for the Microphone Read-out Integrated Circuit

Mechanical characterization of millimetric agarose spheres using a resonant technique

This paper presents a methodology for the mechanical characterization of agarose millimetric spheres using resonant principles. Detection of the modes of vibration was conducted using a low-cost experimental setup based on an electret microphone adapted with a thin latex elastic membrane for the sensing stage and a piezoelectric actuator driven by a conventional transformer for the excitation stage. The identification of vibration modes is supported through an ANSYS Finite Element model of the experimental setup. Experimental and numerical results demonstrate that two modes of vibration, known as Quadrupole and Octupole, appear in the amplitude spectrum and can be used to obtain stiffness values for the samples. Following this approach, Young’s modulus of 209 ± 19.80, 338 ± 35.30 and 646 ± 109 kPa for 2%, 3% and 4% agarose millimetric spheres were calculated.

DESIGN AND IMPLEMENTATION OF MICROCONTROLLER BASED PHOTOACOUSTIC SPECTROMETER AND ITS APPLICATIONS

A compact microcontroller based photoacoustic spectrometer (PAS) has been designed and fabricated. The photoacoustic (PA) cell designed for the present study is of Helmholtz resonator type with a provision to measure the sample behavior as a function of temperature. In this system, an electret microphone is employed to achieve high signal to noise ratio. The microphone compartment is isolated from the sample compartment to avoid the heating effect to the electric microphone which detects the photoacoustic signal. A high-gain low-noise two stage preamplifier, second order bandpass and tunable narrow band-pass filters have been designed with a low noise op-amp LM308 to improve signal quality. C8051F060 microcontroller-based phase sensitive detector has been implemented to measure the amplitude and phase of the signal from the photoacoustic cell. The applications of PAS for phase transition studies on some samples are presented. The designed system is low-cost, very compact and easy to carry the experiments for studying the thermal properties of samples.

A new approach to acoustic insect detection in grain storage: Presentation

Insect pests in grain storages can cause severe financial losses. Infested grain needs to be treated and can be sold only with lower profit. Intense infestation can lead to contamination with mycotoxins and total loss of stock. Therefore, an early detection of insect storage pests is of great importance to farmers and storage keepers but is difficult to obtain in large amounts of grain. Besides conventional detection methods such as insect traps and monitoring of temperature and relative humidity, acoustic monitoring can identify insect infestation. Insects in grain and other stored products produce sounds at a low level during movement and feeding activity. A new acoustic system was developed as part of the project “InsectTap” to increase the detectability of insect sounds. Highly sensitive microphones were installed inside a metal tube that increased the surface on which beetle signals could be detected. Additionally, the tube worked as a beetle trap recording all sounds from even one single beetle inside the trap. The tube system was tested in 1 and 8 m³ boxes filled with wheat. Infestation could be detected at a very early stage about 8 weeks before a temperature rise, or beetles at the grain surface indicated an infestation. In the next step, this “Beetle Sound Tube”-System will be installed in different grain silos aiming for automatic early detection and specific identification of infestation. The information provided to the farmer or storage keeper allows early and specific treatment to reduce losses. Additionally, the introduction of parasitoids via the tube system will be tested to increase the efficacy of biological control.

Impact point estimation system of the rifle based on time difference of arrival method using microphone array

Impact point estimation system of the rifle based on time difference of arrival method using microphone array

Beamforming and maximum likelihood estimation for speech enhancement using dual closely-spaced microphones

Beamforming and maximum likelihood estimation for speech enhancement using dual closely-spaced microphones

Photoacoustic spectroscopy based multi-gas detection using high-sensitivity fiber-optic low-frequency acoustic sensor

We demonstrate a high-sensitivity fiber-optic low-frequency acoustic sensor based on a thin Parylene-C diaphragm. The excellent diaphragm forming ability and good adhesion of Parylene-C make the sensor fabricate up to 9 mm in diameter. For the acoustic pressure of 50 mPa at the frequency of 30 Hz, acoustic testing demonstrates a signal to noise ratio of 37 dB, which is almost seven times higher than a conventional electric microphone. The low-frequency acoustic sensor, together with an infrared thermal radiation source, and a non-resonant cell, constitutes a photoacoustic detection system for multiple trace gases analysis. The detection limits of acetylene (C2H2), methane (CH4), ethane (C2H6), ethylene (C2H4), carbon monoxide (CO) and carbon dioxide (CO2) are achieved to be 0.11, 0.21, 0.13, 0.16, 0.15 and 0.48 parts-per-million, respectively. The detection system is applied to detect mixture of the six gases, and the average deviations of the six gases are not more than 5.0%.

Spotlight: Not a spoon, but maybe a hammer, filter, or microphone

Spotlight: Not a spoon, but maybe a hammer, filter, or microphone

PENGGUNAAN SENSOR AUDIO PADA PEMBUBUTAN: SUATU KAJI EKSPERIMENTAL KEAUSAN PAHAT

This research is the experimental study of cutting tool wear in the turning process using audio sensors to determine the characteristics of tool wear. The benefits derived from this study is as a base to create a tool wear online monitoring system. This system can improve productivity and prevent further losses due to premature tool wear components such as uneven surface, chipping and production defects. Sound signals (audio signals) during the cutting process will be captured by the microphone and processed using LabVIEW software in the form of the time domain signal and frequency domain. These signals can be used as information to build artificial neural networks (ANN) in the online monitoring system. Testing at level 3 is the highest parameters of cutting conditions where the cutting speed of 220 m / min, feed rate 0.12 mm / rev and depth of cut of 0.375 mm. Increasing the level of cutting parameters and flank wear is directly proportional to the audio signal received by the microphone. At these cutting conditions, cutting tool will receive a larger load so that the necessary energy is also great for cutting. As a result, the friction force with the work piece increases so that the audio signal is generated will increase. Keywords: audio, turning, cutting tool

Compressive sensing in wireless sensor network for poultry acoustic monitoring

Abstract: A wireless acoustic sensor network was realized using wireless sensor nodes equipped with microphone condensers, in which its sensor nodes were configured to capture poultry sound data and transmit it via the network to a collection point. A high performance computer can process these large volumes of animal audio signals under different behaviors. By performing data signal processing and analyzing the audio signal, poultry sound can be achieved and then transformed into their corresponding behavioral modes for welfare assessment. In this study, compressive sensing algorithm was developed in consideration of the balance between the power saving from compression ratio and the computational cost, and a low power consumption as well as an inexpensive sensor node was designed as the elementary unit of poultry acoustic data collecting and transmission. Then, a Zigbee-based wireless acoustic sensor network was developed to meet the challenges of short transmission range and limited resources of storage and energy. Experimental results demonstrate that the compressive sensing algorithm can improve the communication performances of the wireless acoustic sensor network with high reliability, low packet loss rate and low energy consumption. Keywords: wireless sensor network, compressive sensing, poultry acoustic monitoring, poultry sound data, power consumption, acoustic data compression DOI: 10.3965/j.ijabe.20171002.2148 Citation: Xuan C Z, Wu P, Zhang L N, Ma Y H, Liu Y Q, Maksim. Compressive sensing in wireless sensor network for poultry acoustic monitoring. Int J Agric & Biol Eng, 2017; 10(2): 94–102.

Effect of dexmedetomidine on high mobility group box -1 protein in off - pump cornary artery bypass

Objective To study the effect of dexmedetomidine on high mobility rate group protein 1 (HMGB-1) in off-pump cornary artery bypass. Methods The patients undergoing off-pump coronary artery bypass graft surgery were selected, and randomly divided into dexmedetomidine group (D group) and control group (C group), n=30 each. Two sets were induced for anesthesia with midazolam, sufentanil, vecuronium, using target controlled infusion of propofol and sufentanil infusion, intermittent injection of vecuronium. Maintain bispectral index (BIS) in the range 40-60. Group D starts induced by filling the dexmedetomidine anesthesia was maintained with the microphone 0.5 μg/(kg·h). After induction of anesthesia (T1), before vascular anastomosis (T2), 6 h after operation (T3), 24 h after operation (T4), 48 h after operation (T5) 5 points respectively for blood 10 ml HMGB-1 Western blotting testing. Results Group D of HMGB-1 in T2, T3, T4, T5, were significantly lower than Group C in T2, T3, T4, T5(T2: 1.60±0.21 vs. 2.51±0.38, P<0.01; T3: 2.16±0.29 vs. 3.75±0.60, P<0.01; T4: 1.85±0.21 vs. 2.57±0.36, P<0.01; T5: 1.90±0.35 vs. 2.95±0.41, P<0.01). Conclusion The application of dexmedetomidine can decrease the content of HMGB-1 in off-pump cornary artery bypass, exert its anti inflammation and immune regulation. Key words: Dexmedetomidine; Off-pump cornary artery bypass; High mobility group box-1 protein

An Accurate Study on Capacitive Microphone with Circular Diaphragm Using a Higher Order Elasticity Theory

THIS STUDY HAS BEEN UNDERTAKEN TO INVESTIGATE THE MECHANICAL BEHAVIOR OF THE CAPACITIVE MICROPHONE WITH CLAMPED CIRCULAR DIAPHRAGM USING MODIFIED COUPLE STRESS THEORY IN COMPARISON TO THE CLASSICAL ONE. PRESENCE OF THE LENGTH SCALE PARAMETER IN MODI-FIED COUPLE STRESS THEORY PROVIDES THE MEANS TO EVALUATE THE SIZE EFFECT ON THE MICROPHONE MECHANICAL BEHAVIOR. INVESTIGATING PULL-IN PHENOMENON AND DYNAMIC BEHAVIOR OF THE MICROPHONE ARE THE MATTERS PROVIDED DUE TO THE APPLICATION OF A STEP DC VOLTAGE. ALSO THE EFFECTS OF DIFFERENT AIR DAMPING COEFFICIENTS ON DYNAMIC PULL-IN VOLTAGE AND PULL-IN TIME HAVE BEEN STUDIED. THE OUTPUT LEVEL OR SENSITIVITY OF THE MICROPHONE HAS BEEN STUDIED BY INVESTIGATING THE FREQUENCY RESPONSE IN TERM OF MAGNITUDE FOR DIFFERENT LENGTH SCALE PARAMETERS TO FIGURE OUT HOW THE LENGTH SCALE PARA-METER AFFECTS ON THE SENSITIVITY OF THE CAPACITIVE MICROPHONE. TO ACHIEVE THESE ENDS, THE NONLINEAR DIFFERENTIAL EQUATION OF THE CIRCULAR DIAPHRAGM HAS BEEN EXTRACTED USING KIRCHHOFF THIN PLATE THEORY. THEN, A STEP-BY-STEP LINEARIZATION METHOD (SSLM) HAS BEEN USED TO ESCAPE FROM THE NONLINEARITY OF THE DIFFERENTIAL EQUATION .AFTERWARDS, GALERKIN-BASED REDUCED-ORDER MODEL HAS BEEN APPLIED TO SOLVE THE OBTAINED EQUATION.

Älter, hörbeeinträchtigt und…. erwerbstätig!

Bisher fehlen in Deutschland ausreichend aussagekraftigen Daten oder Statistiken zur Erwerbsteilhabe von Menschen mit Behinderung, so auch von alteren erwerbstatigen Menschen mit Behinderung. Um diese Forschungslucke fur den Teilbereich von erwerbstatigen Menschen mit einer Horbehinderung in den Blick zu nehmen, wird seit 2009 das Projekt GINKO (Gesetzeswirkungen bei der beruflichen Integration schwerhoriger, ertaubter und gehorloser Menschen durch Kommunikation und Organisation) durchgefuhrt. Ein Ziel der Studie ist die Analyse der Bedingungen der beruflichen Integration von Menschen mit Horbehinderung unter besonderer Berucksichtigung der Frage der Rechtsmobilisierung des SGB IX und dessen konkrete Umsetzung im Arbeitsalltag, insbesondere der behindertengerechten Gestaltung des Arbeitsplatzes auf Grundlage des § 81(4) SGB IX durch z. B. technische Hilfsmittel. Dazu wurden im Rahmen der GINKO-Studie bundesweit Betroffene mit einem standardisierten Fragebogen, der auch online mit Gebardensprachfilmen zur Verfugung stand, schriftlich zu Inhalten der aktuellen Gesetzgebung und der Situation am Arbeitsplatz befragt. Insgesamt beteiligten sich an der GINKO-Umfrage n = 3.189 schwerbehinderte berufstatige Personen, davon waren n = 661 (20,7 %) der Teilnehmenden zwischen 50 und 65 Jahre alt. Der Anteil der Arbeitnehmerinnen in dieser Altersgruppe betrug 48,7 %. Die Ergebnisse des GINKO-Projekt zeigten, dass die durch § 81 Abs.4, SGB IX vorgesehenen Masnahmen zur Gestaltung von behinderungsgerechten Arbeitsplatzen bei alteren horbeeintrachtigten Arbeitnehmenden bisher noch in eher geringem Mase umgesetzt werden. So ergaben die Analysen der Angaben der alteren berufstatigen Teilnehmenden (n = 661) zur Gestaltung ihres Arbeitsplatz, dass lediglich 29,6 % dieser Gruppe ihren Arbeitsplatz insgesamt betrachtet als horgeschadigten gerecht beurteilt. Insbesondere technische Hilfsmittel wie z. B. FM-Anlagen oder Zusatzmikrophone stehen vielen erwerbstatigen Teilnehmenden nicht zur Verfugung, obwohl sie sie benotigen wurden. Auch der fur Menschen mit Horschadigung wichtige Aspekt der Larm-Minderung am Arbeitsplatz wie z. B. Schalldammung wird nur bei etwa einem Drittel der Befragten berucksichtigt. Somit zeigen die Analysen im Rahmen des GINKO-Projekts auf, dass weitere Anstrengungen notig sind, um die vorhandenen gesetzlichen Moglichkeiten konkret umzusetzen.

Syntactic and Semantic Errors in Radiology Reports Associated With Speech Recognition Software.

Speech recognition software (SRS) has many benefits, but also increases the frequency of errors in radiology reports, which could impact patient care. As part of a quality control project, 13 trained medical transcriptionists proofread 213,977 SRS-generated signed reports from 147 different radiologists over a 40 month time interval. Errors were classified as "material" if they were believed to alter interpretation of the report. "Immaterial" errors were subclassified as intrusion/omission or spelling errors. The proportion of errors and error type were compared among individual radiologists, imaging subspecialty, and time periods using .2 analysis and multiple logistic regression, as appropriate. 20,759 (9.7%) reports contained errors; 3,992 (1.9%) contained material errors. Among immaterial errors, spelling errors were more common than intrusion/omission errors (P&lt;.001). Error proportion varied significantly among radiologists and between imaging subspecialties (P&lt;.001). Errors were more common in cross-sectional reports (vs. plain radiography) (OR, 3.72), reports reinterpreting results of outside examinations (vs. in-house) (OR, 1.55), and procedural studies (vs. diagnostic) (OR, 1.91) (all P&lt;.001). Dictation microphone upgrade did not affect error rate (P=.06). Error rate decreased over time (P&lt;.001).

Diversity and Integration of Rotating Machine Health Monitoring Methods

Health monitoring for rotating machines is investigated through two kinds of mock-up experimental data analysis. One is an anomaly mock-up test of roll bearing type rotating machine. Here, inner ring defect anomaly is simulated and its operating data are measured by both attached type accelerometer sensor and non-attached type microphone. Three kinds of signal pre-processing methods, frequency spectrum, principal component analysis and cepstrum, are applied to discriminate normal and abnormal states using several different classification algorithms, such as adaboost or random forest. Through analysis of their performance with the help of receiver operating characteristic (ROC) curve, the importance of diversified health monitoring methods is discussed. Another mock-up experiment is an accelerated test of roll bearing wear. Here, acoustic emission counts, accelerometer signal and wear particle number in lubricating oil are measured. Using these observation data, we make clear the relationships between deterioration mechanisms of bearing and behaviour of different observations.

Робототехника для специальных применений в области физиотерапии

The article describes new robotic systems for specific applications in the field of the regenerative medicine. One of the important directions in the regenerative medicine is the massage physiotherapy. It is a combination of the dosed mechanical techniques in the form of friction, pressure and vibrations applied directly to the surface of a human body. Since a manual application of these actions involves high energy costs, their efficiency and productivity are rather limited. These restrictions can be removed due to the use in the physiotherapy of special robotic systems, which ensure automation of the massage procedures and manual therapy, and their availability for all the patients. The article presents the measuring units of the robotic systems, which ensure the systems' adaptive functionalities, and methods of their calculation and experimental characteristics. It also describes the schemes for a longitudinal movement of the tools intended to improve the effectiveness of the massage and the systems for a loop-massage, giving a holistic effect. A system is presented, which makes it possible to control the depth of the toning processes and relaxation of patients with the help of a biofeedback loop and an advanced system, combining the effect of a simultaneous tactile and musical influence on patients. The sound of music is converted by an electric microphone into an electric signal of a broad range. With the help of bandpass amplifiers this range is divided into three frequency bands. The intensity level of the AC input signal is formed on the output of the rectifiers, a DC voltage signal from which allows us to control the vibration intensity of the corresponding electromechanical vibrators in accordance with the content of the music. All the presented designs are patented.

Paper microphone creates a charge

Paper microphone creates a charge