Papers by David Pérez-Cabo
In this paper, a bootstrap evaluation of the confidence intervals in reverberation time measureme... more In this paper, a bootstrap evaluation of the confidence intervals in reverberation time measurement is presented and discussed. The confidence interval of a data set is usually calculated assuming the population is normally distributed. In the literature published in the recent years it has been shown and discussed how either multimodal or asymmetric probability density functions are possible in reverberation time measurements at low frequencies. As the assumption of normal distribution is not valid for reverberation time measurements at low frequencies, a bootstrap based method to obtain confidence intervals for reverberation time measurements will be described. The proposed method is validated by simulations and by using an extensive measurement dataset of a room. Reasonably good confidence levels are reached in both cases. PACS no. 43.58.+z, 43.60.+d
Using networks of acoustic vector sensors for sound source localization and tracking has become o... more Using networks of acoustic vector sensors for sound source localization and tracking has become of research interest given its importance in a great variety of applications. An Acoustic Vector Sensor (AVS) consists of two or three orthogonal particle velocity sensors in combination with a sound pressure microphone. In several publications it has been proven that multiple sources can be located in three dimensions with a single AVS. Furthermore, it has been demonstrated that ground-based two-dimensional acoustic vector sensors can be used to estimate the elevation of a single source. Two different algorithms for harmonic source localization using a distributed and synchronized network of 2-D AVS are presented and tested in this work. Both algorithms are based on the Direction Of Arrival (DOA) estimate performed by each sensor in the network for every dominant component of the source. Localization and tracking results based on simulations and two extensive measurements of flying aircr...
Measurement of acoustic decays can be problematic at low frequencies: short decays cannot be eval... more Measurement of acoustic decays can be problematic at low frequencies: short decays cannot be eval-uated accurately. Several effects influencing the evaluation will be reviewed in this paper. As new contribution, the measurement uncertainty due to one-third octave band pass filters will be analysed, taking into account the influence of the magnitude response and the phase distortion. It will be shown how the error not only depends on the filter but also on the modal density and the position of the resonances of the system under test within the frequency band. A Monte-Carlo computer simulation has been be set up: the model function is a model of the acoustic decays, where the modal density, the resonances of the system, and the amplitude and phase of the normal modes may be considered as random variables. Once the random input variables and the model function are defined, the un-certainty of acoustic decay measurements can be estimated. Different filters will be analysed: linear phase...
In recent years, there has been growing interest in the development of noise prediction and reduc... more In recent years, there has been growing interest in the development of noise prediction and reduction techniques. The ability to localise problematic sound sources and determine their contribution to the overall perceived sound provides an excellent first step towards reducing noise. Several well-known methods can be applied in order to achieve a detailed acoustic assessment using microphone phased arrays. However, pressure-based solutions encounter difficulties assessing low frequency problems and their performance is often limited by spatial coherence losses. Alternatively, the use of acoustic vector sensor (AVS) offers several advantages in such conditions due to their vector nature. Each AVS is comprised of a pressure microphone and three orthogonal particle velocity sensors, allowing for the sound direction of arrival to be determined at any frequency within the audible frequency range. Sound localisation techniques using AVS are evaluated in this paper, comparing the character...
Applied Acoustics, 2012
ABSTRACT In this paper the error due to the phase response of digital filters on acoustic decay m... more ABSTRACT In this paper the error due to the phase response of digital filters on acoustic decay measurements is analyzed. There are two main sources of errors when an acoustic decay is filtered: the error due to the bandwidth of the filters related to their magnitude response, and the error due to their phase response. In this investigation the two components are separated and the phase error analyzed in terms of the group delay of the filters. Linear phase FIR filters and minimum phase IIR filters fulfilling the class 1 requirements of the IEC 61260 standard have been designed, and their errors compared. This makes it possible to explain the behavior of the phase error and develop recommendations for the use of each filtering technique. The paper is focused on the filtering techniques covered by current versions of the standards for measurement of acoustic decays and in the evaluation of the acoustic decay for narrow filters at low frequencies and low reverberation times (BT < 16).
Acta Acustica united with Acustica, 2011
Wideband absorbers are a fundamental part of non-environment control rooms, providing high absorp... more Wideband absorbers are a fundamental part of non-environment control rooms, providing high absorption in all the frequency range. They consist of huge angled panels hanging in front of the rear wall, the side walls, and the ceiling. As a first step to understand their absorption mechanisms, the sound field in the vicinity of the wideband absorbers of the rear wall has been measured with a p-p intensity probe in the control room at the 'Universidade de Vigo'. The characteristics of the sound field in the proximity of the rear wall will be discussed on the basis of the analysis of the pressure, particle velocity and intensity measurements. PACS no. 43.20.Ks, 43.20.Mv, 43.20.Ye, 43.55.Ev, 43.58.Bh © S. Hirzel Verlag · EAA uncorrected galley proofs -for internal use only ACTA ACUSTICA UNITED WITH ACUSTICA Torres-Guijarro et al.: Study of wideband absorbers Vol. 97 (2011) uncorrected galley proofs -for internal use only ACTA ACUSTICA UNITED WITH ACUSTICA Torres-Guijarro et al.: Study of wideband absorbers Vol. 97 (2011) uncorrected galley proofs -for internal use only Torres-Guijarro et al.: Study of wideband absorbers ACTA ACUSTICA UNITED WITH ACUSTICA Vol. 97 (2011)
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Papers by David Pérez-Cabo