In order to instrumentally or perceptually evaluate and compare the sounds of dental turbines, a representative and reproducible procedure is desirable. DIN EN ISO 14457 (2013) specifies setup and conditions for measuring the maximum A-weighted sound-pressure level in the context of maximum noise limits, not of sound quality. However, this setup may also be used for measurements and recordings ...

Abstract Annular phased array transducers are well known in the medical field, with their main use being in ophthalmology and dermatology, and have started to be employed in the NDT industry relatively recently. Annular arrays consist of a centre circular element and multiple ring-shaped elements of different width. This unique geometry of the probe makes it difficult to determine the generatin...

In recent communication systems side lobe level reduction has become one of the important issue. For applications like digital beam forming it is one of the important factor because it reduces the effect of interference arriving outside the main lobe. This reduction in the interference increases the capacity of the communication systems. This paper presents the different methods for reducing th...

This paper describes an improved spectral subtraction method by using the complementary beamforming microphone array to enhance noisy speech signals for speech recognition. The complementary beamforming is based on two types of beamformers designed to obtain complementary directivity patterns with respect to each other. In this paper, it is shown that the nonlinear subtraction processing with c...

The ground plane affects the characteristics of a planar inverted-F antenna (PIFA) significantly. Using the idea of the high-impedance surface to construct the ground plane, a new type of compact PIFA with a photonic bandgap type (PBG-type) ground plane is proposed. Both the traditional PIFA and the proposed antenna are analyzed using the finite-difference time-domain (FDTD) method in detail. I...

This paper presents a physical demonstration of an audio-range line array used to teach interference of multiple sources in a classroom or laboratory exercise setting. Software has been developed that permits real-time control and steering of the array. The graphical interface permits a user to vary the frequency, the angular response by phase shading, and reduce sidelobes through amplitude sha...

Antennas are becoming crucial in an increasingly growing number of applications namely with the emerging of the wireless internet communications, military systems like aircrafts, missiles and submarines or even oil drilling systems where efficiency, compactness and cost play a decisive role. Nonetheless, a major drawback of such solutions is that the aforementioned criteria are hard to simultan...

This paper presents the simulation and experimental study of the radiation pattern of a meander-line-coil EMAT. A wholly analytical method, which involves the coupling of two models: an analytical EM model and an analytical UT model, has been developed to build EMAT models and analyse the Rayleigh waves' beam directivity. For a specific sensor configuration, Lorentz forces are calculated using ...

This paper presents a novel low-profile antenna with a broadside radiation. The proposed design strategy consists in modifying the layout of a classical Vivaldi antenna, thus resulting in compact dimensions and a broadside radiation pattern. Two different ways of implementing the proposed design approach are presented and discussed. More specifically, experimental data referring to two prototyp...

The human voice is a directional sound source. This property has been explored for more than 200 years, mainly using measurements of participants. Some efforts have made to understand the anatomical parameters that influence speech directivity, e.g., mouth opening, diffraction and reflections due head torso, lips vocal tract. However, these mostly studied separately, without being integrated in...