Marcelo Queiroz

Musicians' Working Memory for Tones, Words, and Pseudowords:

Studies investigating factors that influence tone recognition generally use recognition tests, whereas the majority of the studies on verbal material use self-generated responses in the form of serial recall tests. In the present study we intended to investigate whether tonal and verbal materials share the same cognitive mechanisms, by presenting an experimental instrument that evaluates short-term and working memories for tones, using self-generated sung responses that may be compared to verbal tests. This paradigm was designed according to the same structure of the forward and backward digit span tests, but using digits, pseudowords, and tones as stimuli. The profile of amateur singers and professional singers in these tests was compared in forward and backward digit, pseudoword, tone, and contour spans. In addition, an absolute pitch experimental group was included, in order to observe the possible use of verbal labels in tone memorization tasks. In general, we observed that musical schooling has a slight positive influence on the recall of tones, as opposed to verbal material, which is not influenced by musical schooling. Furthermore, the ability to reproduce melodic contours (up and down patterns) is generally higher than the ability to reproduce exact tone sequences. However, backward spans were lower than forward spans for all stimuli (digits, pseudowords, tones, contour). Curiously, backward spans were disproportionately lower for tones than for verbal material—that is, the requirement to recall sequences in backward rather than forward order seems to differentially affect tonal stimuli. This difference does not vary according to musical expertise.

Efficient Binaural Rendering of Moving Sound Sources Using HRTF Interpolation

Abstract This paper presents efficient techniques for the simulation of continuously moving sound sources, to be presented over headphones, based on the interpolation of Head-Related Transfer Functions (HRTFs). Two novel approaches are presented, one based on interpolating impulse responses in time-domain, and another based on interpolating poles and zeros of low-order Infinite Impulse Response (IIR) approximations of measured HRTF filters. These techniques are apt both for real-time implementation and for multi-user applications where several independent binaural renderings are required. We discuss some of the difficulties of assessing the quality of the results from both objective and subjective points-of-view, and provide objective measurements of the errors caused by the interpolation schemes, as well as of the errors introduced by the use of low-order IIR approximations. A subjective evaluation of these techniques using non-individualized HRTFs suggests that they are able to preserve spatial impression of directions in binaural rendering of static and moving sound sources.

AcMus: an Open, Integrated Platform for Room Acoustics Research

This article describes the design, implementation, and experiences with AcMus, an open and integrated software platform for room acoustics research, which comprises tools for measurement, analysis, and simulation of rooms for music listening and production. Through use of affordable hardware, such as laptops, consumer audio interfaces and microphones, the software allows evaluation of relevant acoustical parameters with stable and consistent results, thus providing valuable information in the diagnosis of acoustical problems, as well as the possibility of simulating modifications in the room through analytical models. The system is open-source and based on a flexible and extensible Java plug-in framework, allowing for cross-platform portability, accessibility and experimentation, thus fostering collaboration of users, developers and researchers in the field of room acoustics.

Conceptual Blending of Harmonic Spaces for Creative Melodic Harmonisation

AbstractIn computational creativity, new concepts can be invented through conceptual blending of two independent conceptual spaces. In music, conceptual blending has been primarily used for analysing relations between musical and extra-musical elements in composed music rather than generating new music. This paper presents a probabilistic melodic harmonisation assistant that employs conceptual blending to combine learned, potentially diverse, harmonic idioms and generate new harmonic spaces that can be used to harmonise melodies given by the user. The key feature of this system is the application of creative conceptual blending to the most common chord transitions (pairs of consecutive chords) of two initial harmonic idioms. The proposed methodology integrates newly created blended chords and transitions in a compound probabilistic harmonic space, that preserves combined characteristics from both initial idioms along with those new chords and transitions within a unified setting. This methodology enables ...

Parametric decomposition of the spectral envelope

In this paper we propose a novel representation of the spectral envelope of speech, using sums of general parametric basis functions (filter bank), including Gaussian, Hann and Nutall. The central frequency and bandwidth of each filter can be adjusted independently for each speech frame as in conventional filter bank analysis. The quality of the representation has been evaluated with respect to a reference spectral envelope obtained from the Harmonic-Stochastic Model [1] (HSM), and also with respect to parameter time stability and separability of different acoustic classes. Numerical results show that the use of the basis functions proposed is an improvement over pure Gaussian models of the spectral envelope.

Techniques for Crosslingual Voice Conversion

The cross lingual voice conversion problem refers to the replacement of a speaker’s timbre or vocal identity in a recorded sentence, assuming that the source speaker and target speaker use different languages. This problem differs from typical voice conversion in the sense that the mapping of acoustical features cannot depend on time-aligned recordings of source and target speakers uttering the same sentences. This paper presents an overview of a general cross lingual voice conversion system and discusses the most important techniques used in each step of the conversion process.

Obtaining General Chord Types from Chroma Vectors

This paper presents two novel strategies for processing chroma vectors corresponding to polyphonic audio, and producing a symbolic representation known as GCT (General Chord Type). This corresponds to a fundamental step in the conversion of general polyphonic audio files to this symbolic representation, which is required for enlarging the current corpus of harmonic idioms used for conceptual blending in the context of the COINVENT project. Preliminary results show that the strategies proposed produce correct results, even though harmonic ambiguities (e.g. between a major chord with added major 6th and a minor chord with minor 7th) might be resolved differently according to each strategy.