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Deep brain stimulation (DBS) is an effective treatment for a variety of brain disorders, including Parkinson's disease, depression and chronic pain. However, there is no reliable method to non-invasively image electric current flow generated by a DBS. In this study, we demonstrate 4D current source density imaging based on the acoustoelectric (AE) effect, which integrates an ultrasound beam with electrical recording, to map current flow produced by a clinical DBS device. AE imaging was able to accurately determine the polarity, magnitude and location of the current densities near the DBS device placed in physiologic saline with a signal-to-noise ratio of 17.1 dB using stimulation parameters similar to what are used on patients. Pulse echo (PE) ultrasound was acquired simultaneously to provide additional information regarding the spatial coordinates and structure of the DBS without need of additional techniques. These results suggest that AE imaging combined with PE ultrasound may provide valuable feedback during and after implantation of a DBS device.

[EN] Fish anatomical vertical dimensions are extracted from a time-of-flight analysis of fish echo shape using narrow bandwidth echosounding of swimming individuals. These vertical dimensions fit a Gumbel distribution model and are successfully correlated with fish weight. The proposed method can be used to estimate the mean weight of fish in aquaculture cages as an alternative to target strength measurements. Full-waveform acquisition and signal correlation techniques permitted to increase the signal-to-noise ratio and to improve the performance against traditional envelope-based echosounding., This work was developed with the financial support of project ARM/1790/010 of the Tecnological Develoment Program of MAGRAMA, Spanish Government. E. Soliveres acknowledges support of Spanish Government grant AP2009-4459 FPU Subprogram.

Distributed temperature sensing has important applications in the long term monitoring of critical enclosures such as containment vessels, flue gas stacks, furnaces, underground storage tanks and buildings for fire risk. This paper presents novel techniques for such measurements, using wire in a spiral configuration and having special embodiments such a notch for obtaining wave reflections from desired locations. Transduction is performed using commercially available Piezo-electric crystal that is bonded to one end of the waveguide. Lower order axisymmetric guided ultrasonic modes were employed. Time of fight (TOF) differences between predefined reflectors located on the waveguides are used to infer temperature profile in a chamber with different temperatures. The L(0,1) wave mode (pulse echo approach) was generated/received in a spiral waveguide at different temperatures for this work. The ultrasonic measurements were compared with commercially available thermocouples.

ACL; International audience; Accurate knowledge of physical and acoustical properties is of importance in many fields of science and engineering. In this work, density and speed of sound measurements of diisopropyl ether (DIPE) are reported. The speed of sound has been measured up to 100 MPa and in the temperature range (293.15–353.15) K by using an apparatus based on a pulse echo technique working in transmission mode, and a correlation for this property was proposed. By using a procedure which rests on the Newton-Laplace relationships, density and its derivatives were determined. To show the reliability of this method, high pressure density measurements were carried out up to 140 MPa and within the temperature interval (293.15–393.15) K with an Anton Paar densitometer. © 2017 Elsevier B.V.

ACL; International audience; Speed of sound measurements were carried out in liquid tris(2-ethylhexyl) trimellitate (TOTM) at pressures up to 200 MPa along isotherms ranging from (293.15 to 373.15) K in order to report data of density and its derivatives. The measurements were performed with a pulse echo technique working at 3 MHz. Additional density and heat capacity measurements were carried out at atmospheric pressure in order to initiate the estimation procedure of volumetric properties from speed of sound integration. Results were compared with density measurements performed with a U-tube densimeter at pressures up to 140 MPa on the same sample. Finally, an equation that correlates density and its derivatives within their estimated uncertainties is given. © 2017 American Chemical Society.

Recent advances in optical transmission and reception of ultrasound have enabled pulse-echo imaging using fiber-optic probes that are suitable for guiding clinical intracardiac and intravascular procedures. In vivo images from pre-clinical models will be presented.

ACL; International audience; The speed of sound of hydrofluoroether fluid HFE-7500 has been measured at pressures up to 100 MPa along isotherms ranging from (293.15 to 353.15) K. The measurements were carried out using a pulse echo technique operating at 3 MHz. Additional high pressure density data were measured up to 140 MPa with temperatures from (293.15 to 393.15) K in order to evaluate isentropic compressibility using speed of sound measurements. A correlation was then proposed to describe both density and speed of sound within their estimated uncertainties and used to evaluate the density and its derivatives. © 2017 Elsevier Ltd

This paper deals with finding of defects, such as cracks, breakdowns and inclusions in rails and in ship plates, by ultrasound technique. Pulse echo method and twin beams technique is some of the ultrasonic inspection methods we have used for thickness measurements and for inspection of the welds. Initially, the thickness of rails and ship plates was measured by ultrasound devices using straight beam transducers and then the weldings of these samples were checked by using angle beam transducers.

El presente estudio evalúa el comportamiento de las variables ultrasónicas en probetas de acero inoxidable dúplex 2205 (UNS31803/ EN1.4462), tratadas térmicamente a 750 °C durante distintos tiempos, con el objetivo de promover la precipitación de fases secundarias, chi (χ) y sigma (σ). Se estudió la evolución microestructural mediante microscopía óptica y electrónica de barrido, y utilizando la técnica ultrasónica pulso eco de contacto. Finalmente, se realizaron ensayos electroquímicos con el objetivo de evaluar la resistencia a la corrosión. Los resultados revelaron que a medida que aumenta el tiempo de tratamiento térmico se produce un incremento de las cantidades relativas de fases χ y σ a lo largo de las interfases ferrita/ferrita y ferrita/austenita, especialmente hacia el interior del grano ferrítico. La velocidad de onda longitudinal y el coeficiente de atenuación presentaron una tendencia que coincide con los cambios microestructurales generados por efecto del tratamiento térmico. La evaluación electroquímica reveló una alta resistencia a la corrosión uniforme. No obstante, se observó una correlación entre el aumento del tiempo de tratamiento térmico con la pérdida de la resistencia a la corrosión localizada.

Current paper describes an application of laser ultrasonic time-of-flight measurement method for estimation of local density of pure tungsten sample. Formulas for estimation of density from speed of sound are derived. Experimental maps of sample density are presented. Accuracy of estimations is up to 37 kg/m 3.

본 연구에서는 초음파 탐상시험의 펄스 반사법으로 각각 용접결함에 따른 초음파 펄스파형모형을 연구하였다. 균열은 예리하고 선명한 신호들을 발생한다. 탐촉자를 결함주위로 이동하면 에코높이는 변한다. 긴 균열에서는 탐촉자가 결함 주위를 원형으로 목돌림주사법을 사용하여 탐상하면 에코높이는 급격히 감소한다. 그 에코 봉우리는 바늘과 같이 얇고 날카롭다. 기공은 단일 결함으로부터 발생하는 에코는 예리하고 선명하다 하지만 집단의 기공들은 다수의 반사들이 중첩되고 트레이스가 들쭉날쭉한 에코가 발생한다. 슬래그 개재물은 크랙과 슬래그 결함위치에서 각각 목돌림 주사법을 사용하여 탐상하면 그 에코형상은 어느 정도 차이를 볼 수 있었다. crack은 그 에코높이가 급격히 변하는 반면에 슬래그 개재물은 증가 ${\rightarrow}$ 감소 ${\rightarrow}$ 증가 ${\rightarrow}$ 감소된다. 또한 다수 밀집된 기공의 위치에서 결함은 대표적 에코형상과 같은 잡다한 에코형상은 슬래그에서는 볼 수 없었다. 용입불량은 결함의 에코형상은 크랙과 같이 날카롭고 예리하게 나타났고, crack과 비슷한 에코형상은 갖고 있었다. 【This study examined the ultrasonic pulse reflection method(UPRM) for testing each ultrasonic pulse waveform model(UPWM) based on weld defects. The sharp crack of a clear signal was generated. The echo height of the defective probes changed according to the location. In a long crack in a circle around the defective probes, the Swivel scanning echo height when using the particle was reduced drastically. The peaks in the echo were thin because the needle was pointed. The porosity defects arising from a single echo was sharp and crisp, but a number of pores of the collective reflection overlapped and ajagged echo was observed. Slag, slag inclusions, cracks, and defects at the Swivel scan of each particle using the echo shape showed difference in the degree. Cracks were revealed as sudden changes in the echo height of the slag inclusions: increase ${\rightarrow}$ decrease ${\rightarrow}$ increase ${\rightarrow}$ decrease. In addition, the location of a number of defects in the dense pore geometry, such as a typical echo sundry, revealed the shape in the slag. Poor penetration of the defect echo, revealed the cracks to have a sharp-edged, crack-like shape with an echo.】

Ultrasonic testing is a sensitive tool not only for defect detection and evaluation of components and structures but also to characterise microstructural features which affect mechanical properties. In this study, four different thermally degraded specimens of 2·25Cr–1Mo steel have been prepared by aging at 873 K for 10 h, 923 K for 20 h, 973 K for 40 h and 973K for 80 h to obtain variation in microstructural features. Mechanical properties of each specimen having different microstructures were investigated using tensile and hardness tests. Ultrasonic parameters of each specimen having different microstructural features were studied by pulse echo technique using 5 MHz longitudinal probe. It has been observed that ultrasonic velocity and attenuation both increased with increase in the size of carbide precipitates obtained due to increased time and temperature of aging. Our results indicated that these ultrasonic parameters could be used as a tool to assess the degraded microstructure of operating c...

This paper deals with the study of A Scans obtaine d from sub assembly head top used in a Prototype Fast Breeder Reactor. A sub-assembly head top is the specimen used to deter mine the effect of bowing on A Scans. The condition of bowing has been simulated. The A Scans are obtained under normal co nditions of the ring and also under simulated bowi ng conditions. The envelope of the A Scans under both the conditions h ave been compared . It is found that the two edges of the ring are clearly indicated through the A Scan. Under normal conditio ns, the two edges have a slight difference in the d epth. This is due to the constructional feature of the object. But under sim ulated conditions, the two edges are obtained at tw o different depths, of magnitude higher than the normal conditions. The sin the A Scans is clearly seen It is observed that greater the tilt given for simulated bowing, larger is the shift in the depth of the two edges of the ring.

The sound velocities of longitudinal and transverse waves of LY12Al are measured under quasi-hydrostatic pressure in a six-side anvil cell using pulse echo overlap technique. From measured sound velocities, the calculated adiabatic bulk modulus is 76.32 GPa. The results are found to be higher than the data obtained under low hydrostatic pressure. The reasons for the differences are analyzed. Different sample assemblies are also considered.

International audience; Blood aggregation occurs when erythrocytes, red blood cells (RBC), agglutinate together into compact stacks of cells called rouleaux. Blood aggregation can then be compared to a liquid-gel transition that appears at low flow regime, and is responsible of the high value of the blood viscosity at low shear rate. This paper will present a physical device that can detect the appearing of this liquid-gel transition using the transmission and reflection properties of ultrasonic waves. In order to detect the liquid-gel transition in resting blood we use the property of an ultrasonic shear wave (5 MHz) to be transmitted or reflected at a glass-liquid interface that is populated with RBC. The setup, as sketched in Figure1, is made of a piezoelectric transducer, a PZT stack that is bonded on the bottom face of a glass cylinder that acts as an acoustic delay line [1]. A burst of signal (2µs) is sent by the PZT toward the glass coverslip, travels through the delay line, bounces at the interfaces and returns with a delay to the PZT where it is detected. Amplitudes of the echo is then compared to input signal in order to extract a reflexion coefficient (r). Experiments are performed both on droplets of healthy blood deposited on glass coverslips and in PDMS microfluidic circuits at low flow strength and at rest. In particular, a spiral shaped microchip, as can be seen in Figure 2, is used both to mimic a vascular network (160x150µm section channels) and to expose a large surface (about 25 mm2) of the sample to the ultrasonic signal [2]. The detection of r over time is coupled with observations of RBCs behaviour during the sample desiccation by optical microscopy to elucidate the dynamics of the drying process of blood. All measurements are carried out at controlled temperature (25 °C) and relative humidity (30-60%). Note that the acoustic power (

The change of the water content in plant stem is the most key study on the regulation of plant growth. In this paper, a plant stem ultrasonic pulse echo apparatus is designed to detect dynamic changes of water content in plant stems. Three sets of experiments are set to detect changes of the water content in different kinds of material and at different level by the changes of the means of the ultrasonic pulse echoes. The results show that the means of the ultrasonic can indicate the water content in the plant stem that is the lower the means of the ultrasonic gets, the higher the water content in the plant stem is.

In 2D 360° Spatial Compounding (SC) envelope detected pulse-echo data from a conventional linear probe is superimposed from 360° in parallel cross-sectional planes to improve B mode image quality. Latest research of our group has shown that extending this concept to 3D by utilizing a motorized 1D array (3D probe) brings along substantial gain in image quality and significance of 360°-SC for diagnosis. However, so far only initial in-vivo results, limited in image quality due to system performance, have been shown for a female breast. In this contribution we will present examples of latest 3D-360°-SC in-vivo results for a female breast and also for a finger joint demonstrating the promising potential of this modality for breast cancer and rheumatoid arthritis diagnosis.

This study is carried out in order to determine the elastic properties of Epoxy Resin (ER) Composites reinforced with various mixtures of China Poplar Char (CPC) and Pine Cone Char (PCC) as biochars by ultrasonic wave velocity measurement method. The prepared chars are mixed with epoxy resin matrix at weight percentages of 10%, 20%, and 30% for preparing the ER/Biochars (BC) composites. The effect of biochar amounts on the elastic properties of the ER/BC composites are investigated by ultrasonic pulse echo overlap method. The morphologies of the samples are investigated by scanning electron microscopy. Based on the findings obtained from the present study, forming of the ER/CPC composites gives better values of elastic properties compared to forming of the ER/PCC composites. According to the obtained results, the composition ratio of 70:30 is the most appropriate composition ratio for both of the ER/CPC and the ER/PCC composites. POLYM. COMPOS., 37:2907–2915, 2016. © 2015 Society of Plastics Engineers

Measurements of the acoustic nonlinearity parameter β are frequently made for early detection of damage in various materials. The practical implementation of the measurement technique has been limited to the through-transmission setup for determining the nonlinearity parameter of the second harmonic wave. In this work, a feasibility study is performed to assess the possibility of using pulse-echo methods in determining the nonlinearity parameter β of solids with a stress-free boundary. The multi-Gaussian beam model is developed based on the quasilinear theory of the KZK equation. Simulation results and discussion are presented for the reflected beam fields of the fundamental and second harmonic waves, the uncorrected β behavior and the properties of total correction that incorporate reflection, attenuation and diffraction effects.

Tunnels are considered as the oldest method of passageway. Underground tunnels are popular from olden eras for connecting places, travelling, and aid for various surface threats. They are also used for illegal activities like smuggling of unlicensed drugs, weapons, currency, gold, explosives, and even human trafficking is being done through these tunnels. These immoral activities are concentrated in national border areas in order to escape from the border security measures. Hence the detection processes of such tunnels in the national security border areas are necessary in order to protect our homeland security systems. The geology plays an important role in the detection of the underground tunnel system procedures. There is no perfect system for the tunnel detection and localization and even today the tunnels revealed in coincidence. The basic principle to find the hollow space (tunnel) is, by sending an ultrasonic frequency signal into the ground, and study the reflected beam from the tunnel or the hollow space. By analyzing the reflected signal characteristics, preliminary detection of a tunnel/void is possible. Basic idea of the detection is to perform the range estimation algorithm (REA) by pulse echo method. From these, we can estimate the depth of the tunnel. The characteristics of the signal at the soil-tunnel (air) reflection interface are to be investigated.

A bearing capacity estimation method for bridge piles was developed. In this method, the pulse echo test was used to select the intact piles; the dynamic stiffness was obtained by the impulse transient response test. A total of 680 bridge piles were tested, and their capacities were estimated. Finally, core drilling analysis was used to check the reliability of this method. The results show that, for intact piles, an obvious positive correlation exits between the dynamic stiffness and bearing capacity of the piles. The core drilling analysis proved that the estimation method was reliable.

The rubber side could be contaminated using the existing pulse echo method because the ultrasonic wave was incident on the rubber side from the interior of the steel motor case, which could lead to the critical disbond defect. To develop the test method which can be replaced the existing method, the ultrasonic wave was incident on steel face of the steel/rubber adhesive test block. Rubber resonance frequencies measured from the steel/rubber adhesive test block were in good agreement with theoretically predicted rubber resonance frequencies. This paper was described about the ultrasonic resonance method to convert the rubber resonance frequency into the rubber thickness.

The objective of this study is to explore the feasibility of using ultrasound to detect mastoid effusion (ME). In the past, ultrasound has been used to measure middle ear effusion (MEE) by injecting water into the external ear canal to measure echoes from the tympanic membrane, which is uncomfortable for the patient. It has been shown that air cells in the mastoid of patients with MEE are filled with fluid, which implies that ME could be a useful indicator of MEE. This study suggests using ultrasound to detect ME as a potentially noninvasive approach for MEE detection. In vitro experiments were performed on ten cadaver samples of the human ear. A single-element 1 MHz transducer was used to measure the mastoid of each cadaver before and after injecting water into the mastoid. The experimental results showed that the relative amplitudes of ultrasonic signals differed significantly between before (0.24 ± 0.09, mean ± standard deviation) and after (0.15 ± 0.03) the water injection (p0.05, t-test), demonstrating that the ultrasonic reflection can be used to detect ME. The location of the human mastoid under the skin behind the ear allows external measurements, and hence ultrasound-based ME detection may be an alternative, noninvasive diagnostic approach to detecting MEE in the future, providing an examination that avoids discomfort.

The analysis of interaction of ultrasonic pulses with different reflectors which are located in elastic media is carried out. A parameter which allows estimating the form of reflector is instantaneous frequency of pulse-echo. This parameter is an unsteady pulse echo characteristic. Instantaneous frequency determination algorithm is to use wavelet transformation which has increased noise immunity. It is shown that the instantaneous frequency value for a pulse echo is often shifted from a rated frequency of piezoelectric transducer. Difference between the frequencies extensively depends on the reflector form.

Ultrasonic is one of the most common uses of non-destructive evaluation technique. It could detect flaws inside the structure and on the surface such as voids, holes and cracks. In this investigation, a 304 steel block with a small hole inside the structure was fabricated. The radius of the hole was evaluated by the pulse-echo ultrasonic technique. In this work, 2.25MHz, 5MHz and 10MHz of incident waves were employed to detect the radius of the hole inside the structure. The errors of a hole with 2.5 mm radius measured by 5 MHz and 10MHz longitudinal wave were 1.15% and 6.6%, respectively. Experimental results showed that the accuracy of flaw sizing detection by ultrasonic technique depends on the frequency of the incident wave.

Ultrasonic signals received by pulse echo technique from plane parallel Zircaloy 2 samples of fixed thickness and of three different microstructures, were subjected to signal analysis, as conventional parameters like velocity and attenuation could not reliably discriminate them. The signals, obtained from these samples, were first sampled and digitized. Modified Karhunen Loeve Transform was used to reduce their dimensionality. A multilayered feed forward Artificial Neural Network was trained using a few signals in their reduced domain from the three different microstructures. The rest of the signals from the three samples with different microstructures were classified satisfactorily using this network.

The aim of this study is to design and implement a noninvasive ultrasonic thickness measurement device that determines the gingiva thickness, which is quite an important criterion in dentistry, by using A-mode ultrasonic method. Operating frequency of the device is selected as 8 MHz, since gingival thickness is quite slight. The measurements are performed as 192.5 μm precision by the implemented system. Surface-mounted devices integrated circuits (SMD ICs) and electronic parts are used in the implementation of the device. Thus, a small-dimension, handheld device has been design and constructed. The transmitter of the device is tested under simulated object, and encouraging results were obtained.

apan Abstract. This paper aims at a quantitative nondestructive evaluation of pipe wall thinning using an electromagnetic acoustic transducer. Type 304 stainless steels sample specimens that are fabricated by a semi ellipse were provided for our experiments. First, results of measurement and simulation experiments are shown using the provided test samples. The variety of simulation results showed good agreement with laboratory experimental results. Second, the sensitivity of pulse echo signals wit h respect to corrosion geometry of pipe wall is investigated. Finally, the feasibility studies of our sizing methodology are summarized for evaluating FAC and early LDI test samples.

The information of acceleration of a highly maneuverable target can be helpful to enhancing the performance of the tracker and facilitating the classification of targets. However, the current radars cannot provide information on the acceleration of the target in signal processing. Conventionally, acceleration is estimated by using Kalman filtering in several pulse echoes. There are limitations and shortcomings in this method because of its low precision. This paper proposes a Hough-ambiguity transformation (HAT) method for estimating the acceleration within one pulse. Simulations results validate the effectiveness of the proposed algorithm under several conditions with different pulse durations, signal to noise ratios (SNR), searching steps and searching radii respectively. Simulation results also show that the performance of the proposed method is superior to that of other methods.

Corrosion of reinforcing steel in concrete is one of the major durability problems faced by civil engineers as they maintain an aging infrastructure. The problem accelerates since steel is embedded inside concrete. If it remains unnoticed inside concrete, it further accelerates and can cause loss of life and property. This article discusses a nonintrusive corrosion monitoring technique for early detection of damages in steel embedded in concrete. Corrosion manifests itself in debond and pitting steel bars. Guided ultrasonic waves offer a potentially attractive solution for this problem. But it is imperative to excite the right mode for detection of a particular type of corrosion. In the present work, longitudinal guided ultrasonic waves have been utilized to monitor notch and debond defects in steel bars in concrete simulating pitting and delamination phenomena caused by corrosion. Two ultrasonic techniques of pulse transmission and pulse echo were used to monitor the healthy and damaged specimens. The developed methodology is successfully applied for real time monitoring of RC beam specimens undergoing accelerated chloride corrosion. The ultrasonic signals effectively relate to the state of reinforcing bars.

The flowmeter is widely used in coal mining because of its higher measurement precision and simple installation without channel project modification. In this paper, a flow measurement method based on velocity-area is investigated, and a functional flowmeter for mining applications with higher precision is designed. The two key parameters, the liquid level and flow velocity are required to be obtained for achieving the proposed method. The proposed flowmeter is composed of three main functional modules: (1) flow velocity detection module based on ultrasonic time difference method, (2) liquid level detection module, and (3) mud level detection module based on ultrasonic pulse echo method. All the measured data are transferred to the monitoring station for analysis and displayed in real-time through M-BUS. The flowmeter is designed focusing on mining applications, and has higher benefits for preventing water disasters in coal mines.

Hollow jewelry made from combination of gold and other material was found in the market. At the outside it is made of gold and the inside layer is made of other material. X-ray fluorescent method cannot detect the inside material that was covered by gold. This paper explained the experimental result of ultrasonic inspection of fake gold used for jewelry. The ultrasonic pulse echo contact method was used to measure longitudinal wave velocity in the gold jewelry. The results of measurements are explained and discussed.

For the first time a novel experimental technique has been used for direct evaluation of acoustic impedance of liquids. Till date researchers have been using ultrasonic velocity and density measurements to compute acoustic impedance and thermodynamic parameters, which are then used to investigate the nature of molecular interactions of solvent molecules in binary, ternary and quaternary liquid mixtures. Evaluation of acoustic impedance directly is a step in minimizing the cumbersome process of measuring velocities and densities separately of solutions having different mole fraction concentration. Acoustic impedances of ten pure polar and non polar solvents have been determined at different temperatures of 298K, 303K and 308K. This is further coupled with inline simultaneous determination of ultrasonic velocities of the solvents. In order to establish the new method, results have been discussed by comparing the calculated ultrasonic velocity from the experimental acoustic impedance, ultrasonic velocity determination by delay time of flight and the literature values of ultrasonic velocity of the pure solvents.

Cooling elements in operating furnaces, such as waffle coolers, finger coolers, cooling staves, and plate coolers, are subject to wearing and deterioration over time. Ultrasonic (UT) pulse echo is an efficient nondestructive testing methodology to monitor the thickness and quality of the cooling blocks through periodical inspections; however, the highly dampening properties of copper and the high temperatures on the hot face of the cooling elements could cause errors in UT thickness measurements. To eliminate potential errors in UT measurements, a study was conducted to determine the correct temperature and velocity distributions and relationship in waffle coolers. In this study, a combination of mathematical modeling and experimental work was used to establish a relationship between the temperature and the speed of ultrasonic waves in copper elements.

The stress–strain measurements of styrene-butadiene rubber (SBR) samples based on various curing systems were used to access the crosslink density of various rubber mixes. Same materials were subjected to various uniaxial compression strains. The thicknesses before compression and after recovery were recorded. After recovery, pulse echo method was used to measure the ultrasonic velocity for the dilatational wave and that of shear wave at a frequency of 2 MHz and at room temperature. Both of the ultrasonic velocities were used to determine the elastic moduli of the samples. The relation between the elastic moduli and the corresponding recovery values were used to determine the crosslink density of samples. The crosslink density values obtained from the two techniques were compared. Butadiene-acrylonitrile (NBR) rubber mix was used to show that the ultrasonic technique is applicable for other rubber compounds. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

During hunting, insectivorous bats such as Eptesicus fuscus progressively vary the repetition rate, duration, frequency and amplitude of emitted pulses such that analysis of an echo parameter by bats would be inevitably affected by other co-varying echo parameters. The present study is to determine the variation of echo frequency selectivity of duration-tuned inferior collicular neurons during different phases of hunting using pulse-echo (P-E) pairs as stimuli. All collicular neurons discharge maximally to a tone at a particular frequency which is defined as the best frequency (BF). Most collicular neurons also discharge maximally to a BF pulse at a particular duration which is defined as the best duration (BD). A family of echo iso-level frequency tuning curves (iso-level FTC) of these duration-tuned collicular neurons is measured with the number of impulses in response to the echo pulse at selected frequencies when the P-E pairs are presented at varied P-E duration and gap. Our data show that these duration-tuned collicular neurons have narrower echo iso-level FTC when measured with BD than with non-BD echo pulses. Also, IC neurons with low BF and short BD have narrower echo iso-level FTC than IC neurons with high BF and long BD have. The bandwidth of echo iso-level FTC significantly decreases with shortening of P-E duration and P-E gap. These data suggest that duration-tuned collicular neurons not only can facilitate bat's echo recognition but also can enhance echo frequency selectivity for prey feature analysis throughout a target approaching sequence during hunting. These data also support previous behavior studies showing that bats prepare their auditory system to analyze expected returning echoes within a time window to extract target features after pulse emission.