Download Objective Evaluations of Synthesised Environmental Sounds
There are a range of different methods for comparing or measuring the similarity between environmental sound effects. These methods can be used as objective evaluation techniques, to evaluate the effectiveness of a sound synthesis method by assessing the similarity between synthesised sounds and recorded samples. We propose to evaluate a number of different synthesis objective evaluation metrics, by using the different distance metrics as fitness functions within a resynthesis algorithm. A recorded sample is used as a target sound, and the resynthesis is intended to produce a set of synthesis parameters that will synthesise a sound as close to the recorded sample as possible, within the restrictions of the synthesis model. The recorded samples are excerpts of selections from a sound effects library, and the results are evaluated through a subjective listening test. Results show that one of the objective function performs significantly worse than several others. Only one method had a significant and strong correlation between the user perceptual distance and the objective distance. A recommendation of an objective evaluation function for measuring similarity between synthesised environmental sounds is made.
Download Resizing Rooms in Convolution, Delay Network, and Modal Reverberators
In music recording and virtual reality applications, it is often desirable to control the perceived size of a synthesized acoustic space. Here, we demonstrate a physically informed method for enlarging and shrinking room size. A room size parameter is introduced to modify the time and frequency components of convolution, delay network, and modal artificial reverberation architectures to affect the listener’s sense of the size of the acoustic space taking into account air and materials absorption.
Download BIVIB: A Multimodal Piano Sample Library Of Binaural Sounds And Keyboard Vibrations
An extensive piano sample library consisting of binaural sounds and keyboard vibration signals is made available through an openaccess data repository. Samples were acquired with high-quality audio and vibration measurement equipment on two Yamaha Disklavier pianos (one grand and one upright model) by means of computer-controlled playback of each key at ten different MIDI velocity values. The nominal specifications of the equipment used in the acquisition chain are reported in a companion document, allowing researchers to calculate physical quantities (e.g., acoustic pressure, vibration acceleration) from the recordings. Also, project files are provided for straightforward playback in a free software sampler available for Windows and Mac OS systems. The library is especially suited for acoustic and vibration research on the piano, as well as for research on multimodal interaction with musical instruments.
Download Position-based Attenuation And Amplification For Stereo Mixes
This paper presents a position-based attenuation and amplification method suitable for source separation and enhancement. Our novel sigmoidal time-frequency mask allows us to directly control the level within a target azimuth range and to exploit a trade-off between the production of musical noise artifacts and separation quality. The algorithm is fully describable in a closed and compact analytical form. The method was evaluated on a multitrack dataset and compared to another position-based source separation algorithm. The results show that although the sigmoidal mask leads to a lower source-to-interference ratio, the overall sound quality measured by the source-to-distortion ratio and the source-to-artifacts ratio is improved.
Download Dimensionality Reduction Techniques for Fear Emotion Detection from Speech
In this paper, we propose to reduce the relatively high-dimension of pitch-based features for fear emotion recognition from speech. To do so, the K-nearest neighbors algorithm has been used to classify three emotion classes: fear, neutral and ’other emotions’. Many techniques of dimensionality reduction are explored. First of all, optimal features ensuring better emotion classification are determined. Next, several families of dimensionality reduction, namely PCA, LDA and LPP, are tested in order to reveal the suitable dimension range guaranteeing the highest overall and fear recognition rates. Results show that the optimal features group permits 93.34% and 78.7% as overall and fear accuracy rates respectively. Using dimensionality reduction, Principal Component Analysis (PCA) has given the best results: 92% as overall accuracy rate and 93.3% as fear recognition percentage.
Download Immersive audio-guiding
An audio-guide prototype was developed which makes it possible to associate virtual sound sources to tourist route focal points. An augmented reality effect is created, as the (virtual) audio content presented through headphones seems to originate from the specified (real) points. A route management application allows specification of source positions (GPS coordinates), audio content (monophonic files) and route points where playback should be triggered. The binaural spatialisation effects depend on user pose relative to the focal points: position is detected by a GPS receiver; for head-tracking, an IMU is attached to the headphone strap. The main application, developed in C++, streams the audio content through a real-time auralisation engine. HRTF filters are selected according to the azimuth and elevation of the path from the virtual source, continuously updated based on user pose. Preliminary tests carried out with ten subjects confirmed the ability to provide the desired audio spatialisation effects and identified position detection accuracy as the main aspect to be improved in the future.
Download Power-balanced Modelling Of Circuits As Skew Gradient Systems
This article is concerned with the power-balanced simulation of analog audio circuits, governed by nonlinear differential algebraic equations (DAE). The proposed approach is to combine principles from the port-Hamiltonian and Brayton-Moser formalisms to yield a skew-symmetric gradient system. The practical interest is to provide a solver, using an average discrete gradient, that handles differential and algebraic relations in a unified way, and avoids having to pre-solve the algebraic part. This leads to a structure-preserving method that conserves the power balance and total energy. The proposed formulation is then applied on typical nonlinear audio circuits to study the effectiveness of the method.
Download Modeling Time-Varying Reactances using Wave Digital Filters
Wave Digital Filters were developed to discretize linear time invariant lumped systems, particularly electronic circuits. The timeinvariant assumption is baked into the underlying theory and becomes problematic when simulating audio circuits that are by nature time-varying. We present extensions to WDF theory that incorporate proper numerical schemes, allowing for the accurate simulation of time-varying systems. We present generalized continuous-time models of reactive components that encapsulate the time-varying lossless models presented by Fettweis, the circuit-theoretic time-varying models, as well as traditional LTI models as special cases. Models of timevarying reactive components are valuable tools to have when modeling circuits containing variable capacitors or inductors or electrical devices such as condenser microphones. A power metric is derived and the model is discretized using the alpha-transform numerical scheme and parametric wave definition. Case studies of circuits containing time-varying resistance and capacitance are presented and help to validate the proposed generalized continuous-time model and discretization.
Download Experimental Study of Guitar Pickup Nonlinearity
In this paper, we focus on studying nonlinear behavior of the pickup of an electric guitar and on its modeling. The approach is purely experimental, based on physical assumptions and attempts to find a nonlinear model that, with few parameters, would be able to predict the nonlinear behavior of the pickup. In our experimental setup a piece of string is attached to a shaker and vibrates perpendicularly to the pickup in frequency range between 60 Hz and 400 Hz. The oscillations are controlled by a linearizion feedback to create a purely sinusoidal steady state movement of the string. In the first step, harmonic distortions of three different magnetic pickups (a single-coil, a humbucker, and a rail-pickup) are compared to check if they provide different distortions. In the second step, a static nonlinearity of Paiva’s model is estimated from experimental signals. In the last step, the pickup nonlinearities are compared and an empirical model that fits well all three pickups is proposed.
Download Waveshaping with Norton Amplifiers: Modeling the Serge Triple Waveshaper
The Serge Triple Waveshaper (TWS) is a synthesizer module designed in 1973 by Serge Tcherepnin, founder of Serge Modular Music Systems. It contains three identical waveshaping circuits that can be used to convert sawtooth waveforms into sine waves. However, its sonic capabilities extend well beyond this particular application. Each processing section in the Serge TWS is built around what is known as a Norton amplifier. These devices, unlike traditional operational amplifiers, operate on a current differencing principle and are featured in a handful of iconic musical circuits. This work provides an overview of Norton amplifiers within the context of virtual analog modeling and presents a digital model of the Serge TWS based on an analysis of the original circuit. Results obtained show the proposed model closely emulates the salient features of the original device and can be used to generate the complex waveforms that characterize “West Coast” synthesis.