Enrico Armelloni

Implementation of real-time partitioned convolution on a DSP board

Convolution using very long filters is required in order to achieve realistic artificial reverberation or spatial effects. Unfortunately, DSP (digital signal processor) platforms have limited computational power (compared with a modern PC) and consequently it is not possible to design very long filters based on typical time-domain, direct-form algorithms, i.e., FIR or IIR structures. To perform this task, other algorithms are necessary. The implementation of a real-time partitioned convolution algorithm on a DSP platform is demonstrated. In this manner, efficient convolution with long impulse responses is attained, with the advantage of low input/output delay.

Cavitation tunnel acoustic characterisation and application to model propeller radiated noise measurements at different functioning conditions

In present work, an acoustic characterisation of the University of Genoa cavitation tunnel is presented, with the aim to obtain suitable transfer functions in order to take into account (at least partially) the effects of the confined environment, particularly important for small-scale facility like the one considered. The acoustic characterisation is performed considering two hydrophones in significantly different positions (inside the tunnel and in an external tank), typical, for different reasons, of noise measurements in cavitation tunnel; the procedure is based on the logarithmic sine sweep signal. The obtained transfer functions have been applied to a series of measurements of model propellers in correspondence to considerably different functioning conditions, in terms of cavitation number and propeller loading, showing the applicability of the procedure and the improvement of the measurement quality, in view of predictions in full scale.

Car cockpit equalization by warping filters

Sound reproduction within a car inside is a difficult task. Reverberation, reflection, echo, noise and vibration are some of the issues to account for. A first step in the direction of increasing sound comfort is that of equalizing the acoustic pressure response in the frequency domain. A direct solution is that of implementing with a convolution filter the inverse of the acoustic measurements in the car cockpit. However this often results in very high number of taps, therefore more complex techniques must be adopted, which rely also on psychoacoustics considerations. In this paper automatic tools to develop warping inverse filters for target car cockpits was designed and validated through experiments in commercial cars.

First description of the sound pressure and particle velocity components of the ambient noise and boat noise recorded at the WWF-Miramare Natural Marine Reserve, Trieste, Italy.

Boat noise represents a chronic source of harassment for fish species, whose communication for inter- and intrasexual selection is based mainly on low-frequency sound signals (Amorim 2006). Investigating the impact of boat noise on target fish species is particularly relevant for coastal marine protected areas (MPAs), which are biologically rich locations deserving protection from anthropogenic pollutants. Although many fish species are primarily sensitive to the kinematic components of the sound field (Popper and Fay 1999), namely, to particle acceleration, boat noises have been characterized so far mostly by means of sound pressure measurements. In this work, the underwater acoustic background noise and the noise produced by a small outboard-engine boat moving at 6 knots were recorded inside the WWF-Natural Marine Reserve of Miramare (Trieste, Italy) by using a novel hydrophonic probe (“Soundfish”) placed on the sea bottom (8 m depth). This allowed for characterization of the sound field not just in terms of sound pressure but also of the three Cartesian components of particle velocity.

An experimental comparative study of 20 Italian opera houses: Measurement techniques

For ‘‘acoustical photography’’ we mean a set of measured impulse responses, which enable us to ‘‘listen’’ at the measured room by means of advanced auralization methods. Once these data sets have been measured, they can be employed in two different ways: objective analysis and listening test. In fact, it is possible to compute dozens of acoustical objective parameters, describing the temporal texture, the spatial effect and the frequency‐domain coloring of each opera house. On the other hand, by means of the auralization technique, it becomes easy to conduct listening experiments with human subjects. This paper focuses principally on the development and specification of the measurement technique, which is the topic assigned to the research unit of Parma, to which the authors belong. It describes the hardware equipment, the software, the electro‐acoustic transducers (microphones and loudspeakers), the measurement positions, the system for automatic displacement of the microphones and the conditions of the ...

Experimental validation of warping filters inside car cockpits

Sound reproduction within a car inside is a difficult task. Reverberation, reflection, echo, noise and vibration are some of the issues to account for. A first step in the direction of increasing sound comfort is that of equalizing the acoustic pressure response in the frequency domain. A direct solution is that of implementing with a convolution filter the inverse of the acoustic measurements in the car cockpit. However this often results in very high number of taps, therefore more complex techniques must be adopted, which rely also on psychoacoustic considerations. An automatic tools to develop warping inverse filters for target car cockpits was designed and validated through experiments in commercial cars.