Download Time mosaics - An image processing approach to audio visualization This paper presents a new approach to the visualization of monophonic audio files that simultaneously illustrates general audio properties and the component sounds that comprise a given input file. This approach represents sound clip sequences using archetypal images which are subjected to image processing filters driven by audio characteristics such as power, pitch and signalto-noise ratio. Where the audio is comprised of a single sound it is represented by a single image that has been subjected to filtering. Heterogeneous audio files are represented as a seamless image mosaic along a time axis where each component image in the mosaic maps directly to a discovered component sound. To support this, in a given audio file, the system separates individual sounds and reveals the overlapping period between sound clips. Compared with existing visualization methods such as oscilloscopes and spectrograms, this approach yields more accessible illustrations of audio files, which are suitable for casual and nonexpert users. We propose that this method could be used as an efficient means of scanning audio database queries and navigating audio databases through browsing, since the user can visually scan the file contents and audio properties simultaneously.
Download Granular analysis/synthesis of percussive drilling sounds This paper deals with the automatic and robust analysis, and the realistic and low-cost synthesis of percussive drilling like sounds. The two contributions are: a non-supervised removal of quasistationary background noise based on the Non-negative Matrix Factorization, and a granular method for analysis/synthesis of this drilling sounds. These two points are appropriate to the acoustical properties of percussive drilling sounds, and can be extended to other sounds with similar characteristics. The context of this work is the training of operators of working machines using simulators. Additionally, an implementation is explained.
Download Towards an Invertible Rhythm Representation This paper investigates the development of a rhythm representation of music audio signals, that (i) is able to tackle rhythm related tasks and, (ii) is invertible, i.e. is suitable to reconstruct audio from it with the corresponding rhythm content being preserved. A conventional front-end processing schema is applied to the audio signal to extract time varying characteristics (accent features) of the signal. Next, a periodicity analysis method is proposed that is capable of reconstructing the accent features. Afterwards, a network consisting of Restricted Boltzmann Machines is applied to the periodicity function to learn a latent representation. This latent representation is finally used to tackle two distinct rhythm tasks, namely dance style classification and meter estimation. The results are promising for both input signal reconstruction and rhythm classification performance. Moreover, the proposed method is extended to generate random samples from the corresponding classes.
Download Assessing The Suitability of the Magnitude Slope Deviation Detection Criterion For Use In Automatic Acoustic Feedback Control Acoustic feedback is a recurrent problem in live sound reinforcement scenarios. Many attempts have been made to produce an automated feedback cancellation system, but none have seen widespread use due to concerns over the accuracy and transparency of feedback howl cancellation. This paper investigates the use of the Magnitude Slope Deviation (MSD) algorithm to intelligently identify feedback howl in live sound scenarios. A new variation on this algorithm is developed, tested, and shown to be much more computationally efficient without compromising detection accuracy. The effect of varying the length of the frequency spectrum history buffer available for analysis is evaluated across various live sound scenarios. The MSD algorithm is shown to be very accurate in detecting howl frequencies amongst the speech and classical music stimuli tested here, but inaccurate in the rock music scenario even when a long history buffer is used. Finally, a new algorithm for setting the depth of howl-cancelling notch filters is proposed and investigated. The algorithm shows promise in keeping frequency attenuation to a minimum required level, but the approach has some problems in terms of time taken to cancel howl.
Download A Computational Model of the Hammond Organ Vibrato/Chorus using Wave Digital Filters We present a computational model of the Hammond tonewheel organ vibrato/chorus, a musical audio effect comprising an LC ladder circuit and an electromechanical scanner. We model the LC ladder using the Wave Digital Filter (WDF) formalism, and introduce a new approach to resolving multiple nonadaptable linear elements at the root of a WDF tree. Additionally we formalize how to apply the well-known warped Bilinear Transform to WDF discretization of capacitors and inductors and review WDF polarity inverters. To model the scanner we propose a simplified and physically-informed approach. We discuss the time- and frequency-domain behavior of the model, emphasizing the spectral properties of interpolation between the taps of the LC ladder.
Download Diffuse-field Equalisation of First-order Ambisonics Timbre is a crucial element of believable and natural binaural synthesis. This paper presents a method for diffuse-field equalisation of first-order Ambisonic binaural rendering, aiming to address the timbral disparity that exists between Ambisonic rendering and head related transfer function (HRTF) convolution, as well as between different Ambisonic loudspeaker configurations. The presented work is then evaluated through listening tests, and results indicate diffuse-field equalisation is effective in improving timbral consistency.
Download Assessing the Effect of Adaptive Music on Player Navigation in Virtual Environments Through this research, we develop a study aiming to explore how adaptive music can help in guiding players across virtual environments. A video game consisting of a virtual 3D labyrinth was built, and two groups of subjects played through it, having the goal of retrieving a series of objects in as short a time as possible. Each group played a different version of the prototype in terms of audio: one had the ability to state their preferences by choosing several musical attributes, which would influence the actual spatialised music they listened to during gameplay; the other group played a version of the prototype with a default, non-adaptive, but also spatialised soundtrack. Time elapsed while completing the task was measured as a way to test user performance. Results show a statistically significant correlation between player performance and the inclusion of a soundtrack adapted to each user. We conclude that there is an absence of a firm musical criteria when making sounds be prominent and easy to track for users, and that an adaptive system like the one we propose proves useful and effective when dealing with a complex user base.
Download Real-Time Modal Synthesis of Crash Cymbals with Nonlinear Approximations, Using a GPU We apply modal synthesis to create a virtual collection of crash cymbals. Synthesizing each cymbal may require enough modes to stress a modern CPU, so a full drum set would certainly not be tractable in real-time. To work around this, we create a GPU-accelerated modal filterbank, with each individual set piece allocated over two thousand modes. This takes only a fraction of available GPU floating-point throughput. With CPU resources freed up, we explore methods to model the different instrument response in the linear/harmonic and non-linear/inharmonic regions that occur as more energy is present in a cymbal: a simple approach, yet one that preserves the parallelism of the problem, uses multisampling, and a more physically-based approach approximates modal coupling.
Download Non-Iterative Schemes for the Simulation of Nonlinear Audio Circuits In this work, a number of numerical schemes are presented in the
context of virtual-analog simulation. The schemes are linearlyimplicit in character, and hence directly solvable without iterative
methods. Schemes of increasing order of accuracy are constructed,
and convergence and stability conditions are proven formally. The
schemes are able to handle stiff problems very efficiently, because
of their fast update, and can be run at higher sample rates to reduce
aliasing. The cases of the diode clipper and ring modulator are
investigated in detail, including several numerical examples.
Download Subjective Evaluation of Sound Quality and Control of Drum Synthesis with Stylewavegan In this paper we investigate into perceptual properties of StyleWaveGAN, a drum synthesis method proposed in a previous publication. For both, the sound quality as well as the control precision StyleWaveGAN has been shown to deliver state of the art performance for quantitative metrics (FAD and MSE of the control parameters). The present paper aims to provide insight into the perceptual relevance of these results. Accordingly, we performed a subjective evaluation of the sound quality as well as a subjective evaluation of the precision of the control using timbre descriptors from the AudioCommons toolbox. We evaluate the sound quality with mean opinion score and make measurements of psychophysical response to the variations of the control. By means of the perceptual tests, we demonstrate that StyleWaveGAN produces better sound quality than state-of-the-art model DrumGAN and that the mean control error is lower than the absolute threshold of perception at every point of measurement used in the experiment.