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- Publication
Articles 1 - 10 of 10
Full-Text Articles in Other Engineering
Introducing Pvspitch: A Pitch Tracking Opcode For Csound, Alan O'Cinneide
Introducing Pvspitch: A Pitch Tracking Opcode For Csound, Alan O'Cinneide
Conference papers
An accurate pitch tracker has many useful applications, whether for creating interactive electroacoustic compositions, music transcription, ethnomusicological research and numerous others. Designed for the Csound sound synthesis and signal processing language, PVSPITCH is an opcode that can be utilised for such purposes. The opcode performs a mathemathical analysis upon Csound's phase vocoder data streams and from this examination, ascertains what it determines to be the signal's pitch. The algorithm handles well many types of signals, including those missing various harmonics, even a fundamental, and also signals with inharmonic partials. The only signal restriction are that it be single voiced, strongly …
Comparison Of Signal Reconstruction Methods For The Azimuth Discrimination And Resynthesis Algorithm, Dan Barry, Robert Lawlor, Eugene Coyle
Comparison Of Signal Reconstruction Methods For The Azimuth Discrimination And Resynthesis Algorithm, Dan Barry, Robert Lawlor, Eugene Coyle
Conference papers
The Azimuth Discrimination and Resynthesis algorithm (ADRess) has been shown to produce high quality sound source separation results for intensity panned stereo recordings. There are however, artifacts such as phasiness which become apparent in the separated signals under certain conditions. This is largely due to the fact that only the magnitude spectra for the separated sources are estimated. Each source is then resynthesised using the phase information obtained from the original mixture. This paper describes the nature and origin of the associated artifacts and proposes alternative techniques for resynthesising the separated signals. A comparison of each technque is then presented.
Onset Detection Using Comb Filters, Mikel Gainza, Bob Lawlor, Eugene Coyle
Onset Detection Using Comb Filters, Mikel Gainza, Bob Lawlor, Eugene Coyle
Conference papers
A technique for detecting note onsets using FIR comb filters which have different filter delays is presented. The proposed onset detector focuses on the inharmonic characteristics of the onset component and the energy increases of the signal. Both properties are combined by utilising FIR comb filters on a frame by frame basis in order to obtain an onset detection functions, which is suitable for detecting slow onsets. The proposed approach improves upon existing methods in terms of the percentage of correct detections in signal processing.
Drum Source Separation Using Percussive Feature Detection And Spectral Modulation, Dan Barry, Derry Fitzgerald, Eugene Coyle, Robert Lawlor
Drum Source Separation Using Percussive Feature Detection And Spectral Modulation, Dan Barry, Derry Fitzgerald, Eugene Coyle, Robert Lawlor
Conference papers
This papers presents a method for the separation and resynthesis of drum sources from single channel polyphonic mixtures. The frequency domain technique involves identifying the presence of a drum using a novel percussive feature detection function, after which the short-time magniture spectrum is estimated and scaled according to an estimated time-amplitude function derived from the percussive measure. In addition to producing high quality separation results, the method described is also a useful pre-process for drum transcription techniques such as Prior Subspace Analysis in the presence of pitched instruments.
Audio Time-Scale Modification Using A Hybrid Time-Frequency Domain Approach, David Dorran, Eugene Coyle, Robert Lawlor
Audio Time-Scale Modification Using A Hybrid Time-Frequency Domain Approach, David Dorran, Eugene Coyle, Robert Lawlor
Conference papers
Frequency-domain approaches to audio time-scale modification introduce a reverberant artefact into the time-scaled output due to a loss in phase coherence between subband components. Whilst techniques have been developed which reduce the presence of this artifact, it remains a source of difficulty. A method of time-scaling is presented that reduces the presence of the reverberation by taking advantage of some flexibility that exists in the choice of phase required so as to maintain horizontal phase coherence along frequency-domain subband components. The approach makes use of appealing aspects of existing time-domain and frequency-domain time-scaling techniques.
Development Of A Computer-Based Violin Teaching Aid: Vitool, Jane Charles, Derry Fitzgerald, Eugene Coyle
Development Of A Computer-Based Violin Teaching Aid: Vitool, Jane Charles, Derry Fitzgerald, Eugene Coyle
Conference papers
This paper considers the development of a violin teaching aid, called ViTool, which is based on violin pedagogy, sound analysis, and comparison of beginner and good player recordings. It is a computer based teaching aid and will ultimately consist of at least four task dependent tools. Typical beginner faults have been identified and features, that best describe them for classification purposes, are considered. The ViTool is not intended as a replacement or electronic teacher, but as a teaching aid. Presently, it seems that no such violin learning aid or tool exists and an opportunity exists for the development of such …
Multi Pitch Estimation By Using Iir Comb Filters, Mikel Gainza, Robert Lawlor, Eugene Coyle
Multi Pitch Estimation By Using Iir Comb Filters, Mikel Gainza, Robert Lawlor, Eugene Coyle
Conference papers
A technique for detecting the pitches of a polyphonic signal is presented. The system utilises modified IIR comb filters, which are generated to ensure that a null (stop band notches) exists at multiples of note frequencies and that a very flat pass band is present in the remain of the spectrum. Thus, the signal spectrum is not distorted after applying the filters to the audio signal, which is the case when using FIR comb filters. the presented approach improves upon an existing multi pitch detection model based on a FIR comb filter framework.
Generalised Prior Subspace Analysis For Polyphonic Pitch Transcription, Derry Fitzgerald, Matt Cranitch, Eugene Coyle
Generalised Prior Subspace Analysis For Polyphonic Pitch Transcription, Derry Fitzgerald, Matt Cranitch, Eugene Coyle
Conference papers
A reformulation of Prior Subspace Analysis (PSA) is presented, which restates the problem as that of fitting an undercomplete signal dictionary to a spectrogram. Further, a generalization of PSA is derived which allows the transcription of polyphonic pitched instruments. This involves the translation of a single frequency prior subspace of a note to approximate other notes, overcoming the problem of needing a separate basis function for each note played by an instrument. Examples are then demonstrated which show the utility of the generalised PSA algorithm for the purposes of polyphonic pitch transcription.
Shifted Non-Negative Matrix Factorisation For Sound Source Separation, Derry Fitzgerald, Matt Cranitch, Eugene Coyle
Shifted Non-Negative Matrix Factorisation For Sound Source Separation, Derry Fitzgerald, Matt Cranitch, Eugene Coyle
Conference papers
A shifted non-negative matrix factorisation algorithm is derived, which offers advantages over previous matrix factorisation techniques for the purposes of single channel source separation. It represents a sound source as translations of a single frequency basis function. These translations approximately correspond to notes played by an instrument. Results are presented for a set of synthetic data, and on a single channel recording of piano and clarinet. Though the system is aimed at musical recordings, the techniques can be applied to any data which contains shifted versions of an underlying factor, and so the algorithm could possibly be used in other …
Holographic Patterning Of Acrylamide-Based Photopolymer Surface, Izabela Naydenova, Emilia Mihaylova, Suzanne Martin, Vincent Toal
Holographic Patterning Of Acrylamide-Based Photopolymer Surface, Izabela Naydenova, Emilia Mihaylova, Suzanne Martin, Vincent Toal
Articles
The patterning of an acrylamide-based photopolymer surface by holographic recording is studied. The patterns are induced by light alone and no post-processing is required. Periodic surface modulation is observed in addition to a volume phase grating. An investigation has been carried out using white light interferometry into the dependence of the amplitude of the photo induced surface relief modulation on the spatial frequency, intensity of recording and sample thickness. The observed dependencies indicate that the diffusion of material during the holographic recording plays a major role in surface relief formation. The possibility for inscription of surface relief patterns opens the …