Download Software Toolbox for Multichannel Sound Reproduction This paper describes a versatile software toolbox, which has been developed for researching, teaching and developing in the field of multichannel sound signal processing. The software system runs on a PC and consists on 5 modules covering the main stages and aspects of multichannel sound reproduction using loudspeakers. A number of new and efficient algorithms have been specially implemented for this software.
Download Realization of a Diffuse Sound Field with a PC-Based Sound Card Solution For the quality assessment of headphones, especially the loudness measuring of headphones, a diffuse sound field is required. At this time a hardware based noise generator, one-third octave filters built up in analog mode as well as boosters are used. In this work a flexible PC-based solution with the aid of a sound card is presented. Therefore ten independent noise generators, generating Gaussian distributed white noise, are needed. The implementation using the ’Dynamic Creation of Pseudorandom Number Genrators’ for ’Mersenne Twister’ is described. A probability transformation to convert equal distributed numbers into Gaussian distributed ones is derived in detail. Furthermore one-third octave filters are designed and implemented according to the ANSI standard. The access to the sound card is provided using the Wave-API library under Microsoft Windows. This work was carried out at Sennheiser electronic GmbH in Wennebostel (Germany) in the development department for cord based headphones.
Download Improved method for extraction of partial’s parameters in polyphonic transcription of piano higher octaves Polyphonic transcription is specially challenging in piano higher octaves due to the complexity of the spectrum of notes and therefore, chords. Besides the fundamental and second partial components, other spectral elements appears. The three peaks related to the unison as well as the second harmonic of the fundamental unison can be distinguished in most measures. Furthermore, intermodulation components are also present when non-linearity is high enough. This paper compares several methods to improve the training process that allows to synthesize the spectral patterns and masks used in transcription methods.
Download Bibliometric Study of the DAFx Proceedings 1998 - 2009 In this paper we present a bibliometric study of the Digital Audio Effects (DAFx) conference proceedings from 1998 to 2009. Using the online DAFx proceedings, we constructed a DAFx database (LaTeX) to study its bibliometric statistics in terms of research topics, growth of literature, authorship distribution, citation patterns, and frequency distribution of scientific productivity. Results showed that the DAFx literature (with quasi-linear accumulative growth) now consists of 722 contributions (including key notes, papers and posters) from 767 unique authors, from which we identified the 20 top DAFx contributors. Using Google Scholar, we identified that the top 10 most cited DAFx papers (between 43 to 65 times) are in majority (8/10) dealing with sound and music analysis (e.g. extraction of sinusoids, musical genre classification, perceived intensity of music, and musical note onset detection). This study also confirmed that the DAFx literature conforms to the Lokta’s law (n=2.0771 and C=0.6336) at 0.01 level of significance using the Kolmogorov-Smirnov test (KS-test) of goodnessof-fit. The DAFx database will serve as the basis for an Author Cocitation Analysis (ACA) and to create a DAFx conferences archive DVD.
Download Simulation of Analog Flanger Effect Using BBD Circuit This paper deals with simulation of BBD circuit based analog flanger effects. The famous Electro-Harmonix Deluxe Electric Mistress flanger effect was used as a case study in this paper. The main attention of this paper is paid to the analysis and simulation of the LFO circuit, the BBD clock generator circuit and BBD circuit simulation of this effect. However, in order to compare the simulation results with measured data, the signal path simulation using the DK-method has been introduced as well.
Download Monophonic transcription with autocorrelation This paper describes an algorithm, which performs monophonic music transcription. A pitch tracker calculates the fundamental frequency of the signal from the autocorrelation function. A continuity-restoration block takes the extracted pitch and determines the score corresponding to the original performance. The signal envelope analysis completes the transcription system, calculating attack-sustain-decay-release times, which improves the synthesis process. Attention is also paid to the extraction of timbre and wavetable synthesis.
Download Room simulation for binaural sound reproduction using measured spatiotemporal impulse responses In binaural sound reproduction systems the incorporation of room simulation is important to improve sound source localisation capabilities. Thus, the localisation error can be decreased, while equivalently an enhanced externality (out of head localisation) is achieved. Previously proposed works are based on simple geometrical approaches for room simulation. In this paper an alternative method using measured room impulse responses (RIRs) is presented. Therefore, it is possible to obtain a convincing acoustical image of an existing room. The RIRs are measured using a circular microphone array to capture both temporal and spatial information of the desired room.
Download Sparse and Structured Decompositions of Audio Signals in Overcomplete Spaces We investigate the notion of “sparse decompositions” of audio signals in overcomplete spaces, ie when the number of basis functions is greater than the number of signal samples. We show that, with a low degree of overcompleteness (typically 2 or 3 times), it is possible to get good approximation of the signal that are sparse, provided that some “structural” information is taken into account, ie the localization of significant coefficients that appears to form clusters. This is illustrated with decompositions on a union of local cosines (MDCT) and discrete wavelets (DWT), that are shown to perform well on percussive signals, a class of signals that is difficult to sparsely represent on pure (local) Fourier bases. Finally, the obtained clusters of individuals atoms are shown to carry higher levels of information, such as a parametrization of partials or attacks, and this is potentially useful in an information retrieval context.
Download The Shape of RemiXXXes to Come: Audio Texture Synthesis with Time-frequency Scattering This article explains how to apply time–frequency scattering, a convolutional operator extracting modulations in the time–frequency domain at different rates and scales, to the re-synthesis and manipulation of audio textures. After implementing phase retrieval in the scattering network by gradient backpropagation, we introduce scale-rate DAFx, a class of audio transformations expressed in the domain of time–frequency scattering coefficients. One example of scale-rate DAFx is chirp rate inversion, which causes each sonic event to be locally reversed in time while leaving the arrow of time globally unchanged. Over the past two years, our work has led to the creation of four electroacoustic pieces: FAVN; Modulator (Scattering Transform); Experimental Palimpsest; Inspection (Maida Vale Project) and Inspection II; as well as XAllegroX (Hecker Scattering.m Sequence), a remix of Lorenzo Senni’s XAllegroX, released by Warp Records on a vinyl entitled The Shape of RemiXXXes to Come.
Download Statistical Measures of Early Reflections of Room Impulse Responses An impulse response of an enclosed reverberant space is composed of three basic components: the direct sound, early reflections and late reverberation. While the direct sound is a single event that can be easily identified, the division between the early reflections and late reverberation is less obvious as there is a gradual transition between the two. This paper explores two statistical measures that can aid in determining a point in time where the early reflections have transitioned into late reverberation. These metrics exploit the similarities between late reverberation and Gaussian noise that are not commonly found in early reflections. Unlike other measures, these need no prior knowledge about the rooms such as geometry or volume.