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Given the rising rate of opioid-related adverse drug events during postsurgical pain management, a nonpharmacologic therapy that could decrease analgesic medication requirements would be of immense value. We designed a prospective, placebo-and-randomized controlled trial to assess the clinical effect of transcutaneous acupoint electrical stimulation (TEAS) on the postoperative patient-controlled analgesia (PCA) requirement for morphine, as well as side effects and recovery profile after inguinal hernia repair. Seventy-one subjects undergoing inguinal hernia repair with a standardized anesthetic technique were randomly assigned to one of three analgesic treatment regimens: PCA + TEAS (n = 24), PCA + sham-TEAS (no electrical stimulation) (n = 24), and PCA only (n = 23). The postoperative PCA requirement, pain scores, opioid-related side effects, and blood cortisol levels were recorded. TEAS treatment resulted in a twofold decrease in the analgesic requirement and decreased pain level reported by the patients. In addition, a significant reduction of cortisol level was reported in the TEAS group at 24 h postoperatively compared to the sham and control groups. We conclude that TEAS is a safe and effective option for reducing analgesic consumption and postoperative pain following inguinal hernia repair.

Ultrasonic projection imaging is similar to X-ray radiography. Nowadays, ultrasonic projection methods have been developed in the set-up of multi-element flat arrays with miniature transducers, where one of the array acts as a transmitter and the other one is a receiver. In the paper, a new method of the projection imaging using a 1024-element circular ultrasonic transducer array is presented. It allows the choice of a projection scanning plane for any angle around a studied object submerged in water. Fast acquisition of measurement data is achieved as a result of parallel switching of opposite transmitting and receiving transducers in the circular array and vertical movement of the array. The algorithm equalizing the length of measurement rays and the distances between them was elaborated for the reconstruction of projection images. Projection research results of breast phantom obtained by means of the elaborated measurement set-up and compared with mammography simulations (acquired through overlapping of X-ray tomographic images) show that ultrasonic projection method presented in this paper (so-called ultrasonic mammogra-phy) can be applied to the woman's breast and be used as a diagnosis for an early detection of cancerous lesions. It can, most of all, be used as an alternative or complementary method to standard mammography, which is harmful because of ionizing radiation and invasive due to the mechanical compression of tissue.

The paper presents an analysis of the results of ultrasound transmission tomography (UTT) imaging of the internal structure of a breast elastography phantom used for biopsy training, and compares them with the results of CT, MRI and, conventional US imaging; the results of the phantom examination were the basis for the analysis of UTT method resolution. The obtained UTT, CT and MRI images of the CIRS Model 059 breast phantom structure show comparable (in the context of size and location) heterogeneities inside it. The UTT image of distribution of the ultrasound velocity clearly demonstrates continuous changes of density. The UTT image of derivative of attenuation coefficient in relation to frequency is better for visualising sharp edges, and the UTT image of the distribution of attenuation coefficient visualises continuous and stepped changes in an indirect way. The inclusions visualized by CT have sharply delineated edges but are hardly distinguishable from the phantom gel background even with increased image contrast. MRI images of the studied phantom relatively clearly show inclusions in the structure. Ultrasonography images do not show any diversification of the structure of the phantom. The obtained examination results indicate that, if the scanning process is accelerated, ultrasound transmission tomography method can be successfully used to detect and diagnose early breast malignant lesions. Ultrasonic transmission tomography imaging can be applied in medicine for diagnostic examination of women’s breasts and similarly for X-ray computed tomography, while eliminating the need to expose patients to the harmful ionising radiation.

For some time, new methods based on a different than acoustic signal analysis are used for speech recognition. The purpose of nonacoustic signals is to allow silent communi‐ cation. One of these methods based on the electromyography signal is generated by the human speech articulation system. This article presents a device for electromyographic (EMG) signal acquisition and the first measurements from its use.

The following work presents the idea of constructing a digitally controlled active piezoceramic transducer matrix for ultrasonic projection imaging of biological media in a similar way as in case of roentgenography (RTG). Multielement ultrasonic probes in the form of flat matrices of elementary piezoceramic transducers require attaching a large number of electrodes in order to activate the individual transducers. This paper presents the idea of minimising the number of transducer connections in an active row-column matrix system. This idea was verified by designing a model of a matrix consisting of 16 ultrasonic transducers with electrode attachments optimised by means of electronic switches in rows and columns and miniature transistor switches in the nodes of the matrix allowing to activate selected transducers. The results of measurements and simulations of parameters of the designed matrix show that it is suitable to be used in projection imaging of biological media as a sending probe. In to use the matrix as a universal sending or receiving probe, it was suggested to add further switches that would eliminate the undesired effect of crosstalks in case of switches used for toggling the transducers in the nodes of the matrix.

Nowadays, in the era of common computerization, transmission and reflection methods are intensively developed in addition to improving classical ultrasound methods (US) for imaging of tissue structure, in particular ultrasound transmission tomography UTT (analogous to computed tomography CT which uses X-rays) and reflection tomography URT (based on the synthetic aperture method used in radar imaging techniques). This paper presents and analyses the results of ultrasound transmission tomography imaging of the internal structure of the female breast biopsy phantom CIRS Model 052A and the results of the ultrasound reflection tomography imaging of a wire sample. Imaging was performed using a multi-modal ultrasound computerized tomography system developed with the participation of a private investor. The results were compared with the results of imaging obtained using dual energy CT, MR mammography and conventional US method. The obtained results indicate that the developed UTT and URT methods, after the acceleration of the scanning process, thus enabling in vivo examination, may be successfully used for detection and detailed characterization of breast lesions in women.

Today, in the age of computerization, experts not only strive to perfect methods of ultrasonographic (US) imaging of tissue structure, but also intensively develop transmission methods, focusing especially on ultrasound transmission tomography (UTT) (analogous to X-ray computed tomography - CT) and ultrasound reflection tomography (URT) based on synthetic aperture method used in radar imaging. The following paper presents and analyses the results of ultrasound transmission tomography of the internal structure of a biopsy CIRS Model 052A breast phantom. The imaging was performed with an internally designed ultrasound computer tomography research system. The obtained results were compared to the imaging results from dual energy CT, MR mammography and traditional US.

A theory of a piezoelectric axisymmetric bimorph is presented in this paper. Bimorphs are often used as electroacoustic transducers, but their use is much wider. A piezoelectic bimorph consists of two or more layers which are placed asymmetrically to the middle surface of the structure. When voltage is supplied to the bimorph, a bending moment is produced which causes transversal deflections of the structure. Average elastic parameters are calculated. Equations for the calculation of bending moments and stretching forces produced by voltage are derived. When the bimorph is a shell of revolution with any shape of meridian, the derived equations can be solved by numerical methods. The finite-element method (FEM) is applied to solve this problem. The bimorph can also be used as a sensor. A theory of such a sensor is also presented. The results obtained by means of the described theory and numerical methods have been verified experimentally or by comparing them with results obtained analytically for a simple structure. It has been proved theoretically that the electric signal produced by a circular transducer clamped on the outer rim of a piezoelectric disc is equal to zero.

Recently surround-sound systems have become popular. The effect of “surrounding“ the listener in sound is achieved by employing acoustic phenomena which influence localizing the source of the sound. Similarly to stereophony system the time, volume and phase interrelations in signals coming from each sound source are taken into account. Additionally the influence of the acoustic system created by the pinna, head and torso on the frequency characteristic of the sound is taken into consideration. This influence is described by the Head-Related Transfer Function (HRTF). The knowledge of the human physical body characteristics’ influence on the perception of the sound source location in space is being more and more frequently applied to building sound systems.

The physical phenomena occurring in sound-absorbing and insulating enclosures are subject of the present paper. These phenomena are: absorption in air and by the sound-absorbing material covering the walls and the coincidence effect. The absorption in the air can be neglected in small size enclosures for low ultrasonic frequencies (20-30 kHz). The coincidence plays a role in decrease of the sound insulation, however the main role play the leaks. The boards made of ceramic fibers have been chosen as the optimal sound-absorbing material. They are dense and have deeply porous structures. The enclosure for insulation of 20-kHz noise produced by a welding machine has been designed and manufactured, and reductions of 25 dB of peak and Leq levels have been achieved.

The following paper presents an idea of minimising the number of connections of individual piezoelectric transducers in a row-column multielement passive matrix system used for imaging of biological media structure by means of ultrasonic projection. It allows to achieve significant directivity with acceptable input impedance decrease. This concept was verified by designing a model of a passive ultrasonic matrix consisting of 16 elementary piezoceramic transducers, with electrode attachments optimised by means of electronic switches in rows and columns. Distributions of acoustic field generated by the constructed matrix model in water and results of the calculations conformed well.

Various types of undesirable crosstalk can occur in ultrasonic arrays consisting of a number of elementary piezoelectric transducers. Crosstalk is a result of deficiency in electrical or mechanical isolation between the array's elements. It is a function of proximity between piezoelectric transducers of the array or between connections. Small piezoceramic transducers tightly located inside of a circle (cylinder or sphere in 3-D systems) are used for in vivo ultrasound tomography imaging of breast tissue. This means that correct switching of transducers makes it possible to quickly acquire tomographic transmission and reflection data. A problem with such arrangements is the occurrence of crosstalk, which introduces specific errors to measurement data. Transmission and reflection tomographic images reconstructed based on ultrasonic measurements with crosstalk are distorted in a characteristic way. This work analyses the effect of crosstalk in a circular transducer array on ultrasound transmission tomography - especially, when used for examination of breast tissue.

NARMAX is a general method for modeling of nonlinear systems. In the paper, an application of this method for modeling of nonlinearities in dynamic loudspeakers is presented. In most cases, a polynomial representation of the NARMAX model causes an ill‐conditioned equation system which indicates that the use of orthogonalization is necessary to solve the system. The high number of coefficients is the main disadvantage of the NARMAX method, and it results in an erroneous model, and an algorithm for identification of coefficients that is noneffective. A modification of the orthogonal algorithm (classical Gram–Schmidt) is presented. It is based on the premise that the coefficient providing the highest error reduction ratio is chosen in every step of the algorithm. The creation of the model stops when the given accuracy is achieved. This way leads to the choice of only the most significant coefficients. The work and effectiveness of this modified algorithm for systems with given nonlinearities at different levels of accuracy of the model are presented in the paper.