AES Rome 2013
Poster Session P17

P17 - Measurements and Modeling

Tuesday, May 7, 10:00 — 11:30 (Foyer)

P17-1 Estimation of Overdrive in Music SignalsLasse Vetter, Queen Mary University of London - London, UK; Michael J. Terrell, Queen Mary University of London - London, UK; Andrew J. R. Simpson, Queen Mary University of London - London, UK; Andrew McPherson, Queen Mary University of London - London, UK
In this paper we report experimental and modeling results from an investigation of listeners’ ability to estimate overdrive in a signal. The term overdrive is used to characterize the result of systematic, level-dependent nonlinearity typical of audio equipment and processors (e.g., guitar amplifiers). Listeners (N=7) were given the task of estimating the degree of overdrive in music signals that had been processed with a static, saturating nonlinearity to introduce varying degrees of nonlinear distortion. A statistical model is proposed to account for the data, which is based on a measure of time-variance in the summed frequency-response deviation introduced by the nonlinearity. This provides a useful “black-box” metric that describes the perceived amount of overdrive introduced by an audio processing device.
Convention Paper 8911 (Purchase now)

P17-2 Mobile Audio Measurements Platform: Toward Audio Semantic Intelligence into Ubiquitous Computing EnvironmentsLazaros Vrysis, Aristotle University of Thessaloniki - Thessaloniki, Greece; Charalampos A. Dimoulas, Aristotle University of Thessaloniki - Thessaloniki, Greece; George M. Kalliris, Aristotle University of Thessaloniki - Thessaloniki, Greece; George Papanikolaou, Aristotle University of Thessaloniki - Thessaloniki, Greece
The current paper presents the implementation of a mobile software environment that provides a suite of professional-grade audio and acoustic analysis tools for smartphones and tablets. The suite includes sound level monitoring, real-time time-frequency analysis, reverberation time, and impulse response measurements, whereas feature-based intelligent content analysis is deployed in terms of long-term audio events detection and segmentation. The paper investigates the implementation of a flexible and user-friendly environment, which can be easily used by non-specialists, providing professional functionality and fidelity of specific-purpose devices and eliminating the mobile-interfacing and hardware limitations. Emphasis is given to the integration of additional capabilities that will offer valuable amenities to the user, having to do with the management of measurement sessions and intelligent cloud-based semantic analysis.
Convention Paper 8912 (Purchase now)

P17-3 System Identification Based on Hammerstein Models Using Cubic SplinesMichele Gasparini, Universitá Politecnica della Marche - Ancona, Italy; Andrea Primavera, Universitá Politecnica della Marche - Ancona, Italy; Laura Romoli, Universitá Politecnica della Marche - Ancona, Italy; Stefania Cecchi, Universitá Politecnica della Marche - Ancona, Italy; Francesco Piazza, Universitá Politecnica della Marche - Ancona (AN), Italy
Nonlinear system modeling plays an important role in the field of digital audio systems whereas most of the real-world devices show a nonlinear behavior. Among nonlinear models, Hammerstein systems are particular nonlinear systems composed of a static nonlinearity cascaded with a linear filter. In this paper a novel approach for the estimation of the static nonlinearity is proposed based on the introduction of an adaptive CatmullRom cubic spline in order to overcome problems related to the adaptation of high-order polynomials necessary for identifying highly nonlinear systems. Experimental results confirm the effectiveness of the approach, making also comparisons with existing techniques of the state of the art.
Convention Paper 8913 (Purchase now)

P17-4 Impulse Responses Measured with MLS or Swept-Sine Signals: A Comparison between the Two Methods Applied to Noise Barrier MeasurementsPaolo Guidorzi, University of Bologna - Bologna, Italy; Massimo Garai, University of Bologna - Bologna, Italy
A sound source and a microphone grid are used for measuring a set of impulse responses with the purpose of estimating the in-situ acoustical characteristics of noise barriers (sound reflection and airborne sound insulation) following the CEN/TS 1793-5 European standard guidelines as improved by the European project QUIESST. The impulse responses are measured using MLS (Maximum Length Sequence) and Swept-sine signals. The acoustical characteristics of the noise barrier, obtained using the two signals, are generally equivalent, but in some critical measurement conditions a discrepancy can be found. Differences and advantages between measurements, obtained by means of MLS or Swept-sine methods are analyzed and discussed in this paper.
Convention Paper 8914 (Purchase now)

P17-5 Polar Measurements of Harmonic and Multitone Distortion of Direct Radiating and Horn Loaded TransducersMattia Cobianchi, Lavoce Italiana - Colonna (RM), Italy; Fabrizio Mizzoni, Sapienza University of Rome - Rome, Italy; Aurelio Uncini, Sapienza University of Rome - Rome, Italy
While extensive literature is available on the topic of polar pattern measurements and predictions of loudspeakers’ fundamental SPL, only a single paper to our knowledge deals with the polar pattern of nonlinear distortions, in particular with harmonic distortion products of cone type loudspeakers. This paper contains the first results of a more thorough study intended as a complement to fill the gap both in measurement techniques and loudspeaker type. Relative and absolute harmonic distortion as well as relative and absolute multitone distortion, indeed, have been measured for cone, dome, and horn loaded transducers.
Convention Paper 8915 (Purchase now)

P17-6 An Efficient Nonlinear Acoustic Echo Canceller for Low-Cost Audio DevicesDanilo Comminiello, Sapienza University of Rome - Rome, Italy; Antonio Grosso, bdSound - Milan, Italy; Fabio Cagnetti, bdSound - Milan, Italy; Aurelio Uncini, Sapienza University of Rome - Rome, Italy
One of the most challenging problems to address in the modeling of acoustic channels is the presence of nonlinearities generated by loudspeakers. This problem has become even more widespread due to the growing availability of low-cost devices that introduce a larger amount of distortions and decrease the quality of hands-free speech communication. In order to reduce the effect of loudspeaker nonlinearities on the speech quality, nonlinear acoustic echo cancellers are adopted. In this paper we present a new adaptive filtering structure for the reduction of nonlinearities in the acoustic path, based on a nonlinear transformation of the input audio signal by means of functional links. We use such a nonlinear model in conjunction with a linear filter providing a nonlinear adaptive architecture for acoustic applications. Experimental results prove the effectiveness of the proposed model in reducing loudspeaker nonlinearities affecting speech signals.
Convention Paper 8916 (Purchase now)

P17-7 Radiation Pattern Differences between Electric Guitar AmplifiersJustin Mathew, New York University - New York, NY, USA; Stephen Blackmore, New York University - New York, NY, USA
Various aspects of electric guitar amplifiers can differentiate them from one another. Two of the major differentiating characteristics are frequency response and unique radiation patterns. These characteristics are directly related to differences in shape, size, and circuit configuration between different guitar amplifier models. In this paper the differences in radiation patterns of multiple guitar amplifiers will be presented as well a method of classifying the differences.
Convention Paper 8917 (Purchase now)

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