282 research outputs found
Digital Signal Processing
Contains an introduction and reports on twenty research projects.National Science Foundation (Grant ECS 84-07285)U.S. Navy - Office of Naval Research (Contract N00014-81-K-0742)National Science Foundation FellowshipSanders Associates, Inc.U.S. Air Force - Office of Scientific Research (Contract F19628-85-K-0028)Canada, Bell Northern Research ScholarshipCanada, Fonds pour la Formation de Chercheurs et l'Aide a la Recherche Postgraduate FellowshipCanada, Natural Science and Engineering Research Council Postgraduate FellowshipU.S. Navy - Office of Naval Research (Contract N00014-81-K-0472)Fanny and John Hertz Foundation FellowshipCenter for Advanced Television StudiesAmoco Foundation FellowshipU.S. Air Force - Office of Scientific Research (Contract F19628-85-K-0028
Analysis and resynthesis of polyphonic music
This thesis examines applications of Digital Signal Processing to the analysis, transformation, and resynthesis of musical audio. First I give an overview of the human perception of music. I then examine in detail the requirements for a system that can analyse, transcribe, process, and resynthesise monaural polyphonic music. I then describe and compare the possible hardware and software platforms. After this I describe a prototype hybrid system that attempts to carry out these tasks using a method based on additive synthesis. Next I present results from its application to a variety of musical examples, and critically assess its performance and limitations. I then address these issues in the design of a second system based on Gabor wavelets. I conclude by summarising the research and outlining suggestions for future developments
Advanced automatic mixing tools for music
PhDThis thesis presents research on several independent systems that when
combined together can generate an automatic sound mix out of an unknown set
of multi‐channel inputs. The research explores the possibility of reproducing
the mixing decisions of a skilled audio engineer with minimal or no human
interaction. The research is restricted to non‐time varying mixes for large room
acoustics. This research has applications in dynamic sound music concerts,
remote mixing, recording and postproduction as well as live mixing for
interactive scenes.
Currently, automated mixers are capable of saving a set of static mix
scenes that can be loaded for later use, but they lack the ability to adapt to a
different room or to a different set of inputs. In other words, they lack the
ability to automatically make mixing decisions. The automatic mixer research
depicted here distinguishes between the engineering mixing and the subjective
mixing contributions. This research aims to automate the technical tasks related
to audio mixing while freeing the audio engineer to perform the fine‐tuning
involved in generating an aesthetically‐pleasing sound mix. Although the
system mainly deals with the technical constraints involved in generating an
audio mix, the developed system takes advantage of common practices
performed by sound engineers whenever possible. The system also makes use
of inter‐dependent channel information for controlling signal processing tasks
while aiming to maintain system stability at all times. A working
implementation of the system is described and subjective evaluation between a
human mix and the automatic mix is used to measure the success of the
automatic mixing tools
Real-time Sound Source Separation For Music Applications
Sound source separation refers to the task of extracting individual sound sources from some number of mixtures of those sound sources. In this thesis, a novel sound source separation algorithm for musical applications is presented. It leverages the fact that the vast majority of commercially recorded music since the 1950s has been mixed down for two channel reproduction, more commonly known as stereo. The algorithm presented in Chapter 3 in this thesis requires no prior knowledge or learning and performs the task of separation based purely on azimuth discrimination within the stereo field. The algorithm exploits the use of the pan pot as a means to achieve image localisation within stereophonic recordings. As such, only an interaural intensity difference exists between left and right channels for a single source. We use gain scaling and phase cancellation techniques to expose frequency dependent nulls across the azimuth domain, from which source separation and resynthesis is carried out. The algorithm is demonstrated to be state of the art in the field of sound source separation but also to be a useful pre-process to other tasks such as music segmentation and surround sound upmixing
A History of Audio Effects
Audio effects are an essential tool that the field of music production relies upon. The ability to intentionally manipulate and modify a piece of sound has opened up considerable opportunities for music making. The evolution of technology has often driven new audio tools and effects, from early architectural acoustics through electromechanical and electronic devices to the digitisation of music production studios. Throughout time, music has constantly borrowed ideas and technological advancements from all other fields and contributed back to the innovative technology. This is defined as transsectorial innovation and fundamentally underpins the technological developments of audio effects. The development and evolution of audio effect technology is discussed, highlighting major technical breakthroughs and the impact of available audio effects
Modelling, Simulation and Data Analysis in Acoustical Problems
Modelling and simulation in acoustics is currently gaining importance. In fact, with the development and improvement of innovative computational techniques and with the growing need for predictive models, an impressive boost has been observed in several research and application areas, such as noise control, indoor acoustics, and industrial applications. This led us to the proposal of a special issue about “Modelling, Simulation and Data Analysis in Acoustical Problems”, as we believe in the importance of these topics in modern acoustics’ studies. In total, 81 papers were submitted and 33 of them were published, with an acceptance rate of 37.5%. According to the number of papers submitted, it can be affirmed that this is a trending topic in the scientific and academic community and this special issue will try to provide a future reference for the research that will be developed in coming years
Application of sound source separation methods to advanced spatial audio systems
This thesis is related to the field of Sound Source Separation (SSS). It addresses the development
and evaluation of these techniques for their application in the resynthesis of high-realism sound scenes by
means of Wave Field Synthesis (WFS). Because the vast majority of audio recordings are preserved in twochannel
stereo format, special up-converters are required to use advanced spatial audio reproduction formats,
such as WFS. This is due to the fact that WFS needs the original source signals to be available, in order to
accurately synthesize the acoustic field inside an extended listening area. Thus, an object-based mixing is
required.
Source separation problems in digital signal processing are those in which several signals have been mixed
together and the objective is to find out what the original signals were. Therefore, SSS algorithms can be applied
to existing two-channel mixtures to extract the different objects that compose the stereo scene. Unfortunately,
most stereo mixtures are underdetermined, i.e., there are more sound sources than audio channels. This
condition makes the SSS problem especially difficult and stronger assumptions have to be taken, often related to
the sparsity of the sources under some signal transformation.
This thesis is focused on the application of SSS techniques to the spatial sound reproduction field. As a result,
its contributions can be categorized within these two areas. First, two underdetermined SSS methods are
proposed to deal efficiently with the separation of stereo sound mixtures. These techniques are based on a
multi-level thresholding segmentation approach, which enables to perform a fast and unsupervised separation of
sound sources in the time-frequency domain. Although both techniques rely on the same clustering type, the
features considered by each of them are related to different localization cues that enable to perform separation
of either instantaneous or real mixtures.Additionally, two post-processing techniques aimed at
improving the isolation of the separated sources are proposed. The performance achieved by
several SSS methods in the resynthesis of WFS sound scenes is afterwards evaluated by means of
listening tests, paying special attention to the change observed in the perceived spatial attributes.
Although the estimated sources are distorted versions of the original ones, the masking effects
involved in their spatial remixing make artifacts less perceptible, which improves the overall
assessed quality. Finally, some novel developments related to the application of time-frequency
processing to source localization and enhanced sound reproduction are presented.Cobos Serrano, M. (2009). Application of sound source separation methods to advanced spatial audio systems [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8969Palanci
Numerical Simulation of a Tube-Delay Audio Effect
A virtual tube delay effect based on the real-time simulation of acoustic wave propagation in a garden hose is presented. The thesis describes the acoustic measurements conducted and the analysis of the sound propagation in long narrow tubes. \nDelay lines and digital filters were designed to simulate the propagation delay, losses, and reflections from the end of the tube. A stereo delay effect plugin in PURE DATA has been also implemented
The creation of a binaural spatialization tool
The main focus of the research presented within this thesis is, as the title suggests, binaural spatialization.
Binaural technology and, especially, the binaural recording technique are not particu-larly recent. Nevertheless, the interest in this technology has lately become substantial due to the increase in the calculation power of personal computers, which started to allow the complete and accurate real-time simulation of three-dimensional sound-fields over headphones.
The goals of this body of research have been determined in order to provide elements of novelty and of contribution to the state of the art in the field of binaural spatialization. A brief summary of these is found in the following list:
• The development and implementation of a binaural spatialization technique with Distance Simulation, based on the individual simulation of the distance cues and Binaural Reverb, in turn based on the weighted mix between the signals convolved with the different HRIR and BRIR sets;
• The development and implementation of a characterization process for modifying a BRIR set in order to simulate different environments with different characteristics in terms of frequency response and reverb time;
• The creation of a real-time and offline binaural spatialization application, imple-menting the techniques cited in the previous points, and including a set of multichannel(and Ambisonics)-to-binaural conversion tools.
• The performance of a perceptual evaluation stage to verify the effectiveness, realism, and quality of the techniques developed, and
• The application and use of the developed tools within both scientific and artistic “case studies”.
In the following chapters, sections, and subsections, the research performed between January 2006 and March 2010 will be described, outlining the different stages before, during, and after the development of the software platform, analysing the results of the perceptual evaluations and drawing conclusions that could, in the future, be considered the starting point for new and innovative research projects
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