Noise within rail vehicles: a neural networks based experimental approach.

3d-Mapping Of Multiple Mirror Sources In A Room: A Two Channel Intensimetric Method.

A large lecture theatre was analyzed by using a 3D intensimetric measurement method. Sweep signal providing the excitation of the environment was sent to an isotropic source. Sound intensity probe was positioned in some test points of the room and sound intensity vector decay was measured for each of them. The sound board of a PC was utilized to acquire couples of impulse responses for each sound intensity vector component. These signals were combined by using an algorithm implemented in Lab VIEW. Mirror sources were localized and visualized in a three-dimensional map for each measurement point. Resuls are presented as orthogonal projections and 3D-diagrams.

Time - frequency analysis in an open - air theater

Acoustics measurements have been carried out along the steps of an ancient open-air theater. Source positions were fixed in several points in the orchestra while microphones, radially placed, were rotated sector by sector, spatially sampling the cavea. Measurements analysis allowed some speech and music sound quality index calculation for each source-microphone couple. Moving from the observation of acoustic quality indexes a time-frequency analysis of impulse response is presented in this paper. Timefrequency analysis of impulse response gives hints for new considerations about the sound field in this peculiar environment.

Vertical Line Array (VLA) Beam - Forming Algorithm with constant beam width.

The algorithm proposed is a beam-forming algorithm. Many beam-steering and beam-forming algorithms exist and they are all based on the control of delay times between the signals driving the loudspeakers of the line array; this kind of control produces a variable beam-width depending on steering angle and frequency. In our case beam width doesn't depend on frequency and steering angle because a specific beam forming technique was applied by shading the amplitudes of signals for each element of the array according to the frequency applied. Furthermore a weighting function was utilized for spatial windowing. Spatial windowing allows reduction of secondary lobes without varying the directivity …

Caratteristiche in regime impulsivo del teatro antico di Segesta.

A study of the acoustic qualities of the ancient theatre in Segesta

Although many centuries have passed, in many ancient theatres evocative theatrical performances still take place, especially during summer. Greek and Latin architects’ care for equilibrium of proportions offers not only an intense quality of view but also a high quality acoustics. In this study we made an analysis both theoretical and experimental of the acoustic qualities of the ancient theatre of Segesta, in Sicily, an open-air theatre of almost 4000 seats, actually difficult to date with precision (II century B.C. or IV century B.C.). By the studying of Vitruvius treatise, "De Architectura", the comprehension of geometrical methods and proportions used to plan the theatre was made possib…