This letter explores the effect of the directivity of a source on time reversal acoustic focusing of energy. A single loudspeaker produces an airborne focus of sound in a reverberation chamber and in a classroom. Individual foci are created at microphone positions that surround the loudspeaker. The primary axis of the loudspeaker is then rotated and experiments are repeated to average out the r...

This paper presents a numerical approach that projects frequency-dependent directivity patterns of classic recording microphones onto steerable beams created with a spherical microphone array. In an anechoic chamber, the spatial and timbral characteristics of a legacy recording microphone and the characteristics of a 120-channel spherical microphone array were measured. Using a least-square mat...

A method to improve the directivity of the microstrip coupler is presented. The width of the coupler is modified for phase velocity compensation which results in high directivity. Using this procedure, a 15 dB coupler is designed and simulated at 0.9 GHz using SONNET software. A high directivity of 46 dB is obtained. The validity of the design concept is verified and compared with conventional ...

Multimode sound radiation from an unflanged, semi-infinite, rigid-walled circular duct with uniform subsonic mean flow everywhere is investigated theoretically. The multimode directivity depends on the amplitude and directivity function of each individual cut-on mode. The amplitude of each mode is expressed as a function of cut-on ratio for a uniform distribution of incoherent monopoles, a unif...

This paper presents an investigation of a pilot signal influence on directivity of self-phased array under conditions of multipath propagation (either reflections or jamming signals). A suggestion is made that an average reduction in directivity owing to the cutting off (or “dropping out”) of some channels of the array be used as a criterion of this influence. It has been shown that an essentia...

Both diagnostic and therapeutic ultrasound applications require an understanding of the directivity patterns on the transducers to design ultrasound equipment and faithfully characterize the acoustic output from medical ultrasound devices. Since each ultrasound transducer has its own specific directivity pattern, the measurement of the directivity pattern is necessary. The objectives of this wo...

This paper reports on the implementation of a moving sound source and receiver with directivity in two-dimensional finite-difference time-domain (FDTD) method. A fundamental solution monopole is theoretically derived. Then, dipole obtained by differentiating space. Finally, monopole, dipole, cardioid sources Numerical experiments performed field showed that effect velocity amplitude differs for...

The aim of this research is to create a microphone array on a rigid sphere that could be used for teleconferences and for recording of music with the aim of five-channel loudspeaker surround sound reproduction. Experiments were undertaken, within a MATLAB environment, by running computer simulations that tested the directivity of a rigid sphere microphone array in both near and far field. The s...