Download A Preliminary Study on Sound Delivery Methods for Footstep Sounds In this paper, we describe a sound delivery method for footstep sounds, investigating whether subjects prefer static rendering versus dynamic. In this case, dynamic means that the sound delivery method simulates footsteps following the subject. An experiment was run in order to assess subjects’ preferences regarding the sound delivery methods. Results show that static rendering is not significantly preferred to dynamic rendering, but subjects disliked rendering where footstep sounds followed a trajectory different from the one they were walking along.
Download Generalizing the Reflection Model by the Use of a Particle Tracing Method Splitting the reflection phenomenon in a specular and a dioeuse one, current acoustic quality prediction methods can't deal with real materials. In this paper, we describe the implementation of a particle tracing method that can deal with a general model of reflection, the bidirectional reflectance distribution function. Furthermore, being based on the Monte-Carlo methods, this method is not sensitive to combinatorial explosion. The flexibility of the particle tracing method make it a good test bed for comparisons and evaluations of source or reflection models.
Download FFT analysis as a creative tool in live performance This paper describes the use of real time spectral analysis to enhance the creative opportunities in improvised live electronics/instrumental performance. FFT analysis allows musicians to observe in performance a visual representation of the spectrum, displaying the spectral characteristics of audio resulting from performance activity and/or computer processing. These characteristics can then be explored during performance, assigning areas of special interest within the spectrum to parameters which in turn control (or at least influence) electronic processing. This creates an effective, easily manipulated but potentially highly complex performance environment, encouraging further interaction between improvising performers, and allowing subtle and complex links to emerge between the timbral features of actual music (result) and the act of performance (cause). We hope to increase awareness of the performance-specific potential of familiar analytical tools, of which FFT is one example, and their unfulfilled creative potential.
Download Hybrid room impulse response synthesis in digital waveguide mesh based room acoustics simulation The digital waveguide mesh (DWM) and related finite difference time domain techniques offer significant promise for room acoustics simulation problems. However high resolution 3-D DWMs of large spaces remain beyond the capabilities of current desktop based computers, due to prohibitively long run-times and large memory requirements. This paper examines how hybrid room impulse response synthesis might be used to better enable virtual environment simulation through the use of otherwise computationally expensive DWM models. This is facilitated through the introduction of the RenderAIR virtual environment simulation system and comparison with both real-world measurements and more established modelling techniques. Results demonstrate good performance against acoustic benchmarks and significant computational savings when a 2-D DWM is used as part of an appropriate hybridization strategy.
Download A Common-Slopes Late Reverberation Model Based on Acoustic Radiance Transfer In rooms with complex geometry and uneven distribution of energy losses, late reverberation depends on the positions of sound sources and listeners. More precisely, the decay of energy is characterised by a sum of exponential curves with position-dependent amplitudes and position-independent decay rates (hence the name common slopes). The amplitude of different energy decay components is a particularly important perceptual aspect that requires efficient modeling in applications such as virtual reality and video games. Acoustic Radiance Transfer (ART) is a room acoustics model focused on late reverberation, which uses a pre-computed acoustic transfer matrix based on the room geometry and materials, and allows interactive changes to source and listener positions. In this work, we present an efficient common-slopes approximation of the ART model. Our technique extracts common slopes from ART using modal decomposition, retaining only the non-oscillating energy modes. Leveraging the structure of ART, changes to the positions of sound sources and listeners only require minimal processing. Experimental results show that even very few slopes are sufficient to capture the positional dependency of late reverberation, reducing model complexity substantially.
Download Keytar: Melodic control of multisensory feedback from virtual strings A multisensory virtual environment has been designed, aiming at recreating a realistic interaction with a set of vibrating strings. Haptic, auditory and visual cues progressively istantiate the environment: force and tactile feedback are provided by a robotic arm reporting for string reaction, string surface properties, and furthermore defining the physical touchpoint in form of a virtual plectrum embodied by the arm stylus. Auditory feedback is instantaneously synthesized as a result of the contacts of this plectrum against the strings, reproducing guitar sounds. A simple visual scenario contextualizes the plectrum in action along with the vibrating strings. Notes and chords are selected using a keyboard controller, in ways that one hand is engaged in the creation of a melody while the other hand plucks virtual strings. Such components have been integrated within the Unity3D simulation environment for game development, and run altogether on a PC. As also declared by a group of users testing a monophonic Keytar prototype with no keyboard control, the most significant contribution to the realism of the strings is given by the haptic feedback, in particular by the textural nuances that the robotic arm synthesizes while reproducing physical attributes of a metal surface. Their opinion, hence, argues in favor of the importance of factors others than auditory feedback for the design of new musical interfaces.
Download A Stochastic State-Space Phase Vocoder for Synthesis of Roughness This paper presents an implementation of the phase vocoder within a Gaussian state-space framework. Rather than formulate the problem as a deterministic evolution of frequencies centered around a given bin, this evolution is treated stochastically by introducing noise into the dynamics matrix of the recursive state equation. This produces effects on the roughness of the input sound, which vary depending on the position within the matrix where the noise is added, how it is propagated throughout the matrix and further by the variance of the noise input.
Download Impedance Synthesis for Hybrid Analog-Digital Audio Effects Most real systems, from acoustics to analog electronics, are
characterised by bidirectional coupling amongst elements rather
than neat, unidirectional signal flows between self-contained modules. Integrating digital processing into physical domains becomes
a significant engineering challenge when the application requires
bidirectional coupling across the physical-digital boundary rather
than separate, well-defined inputs and outputs. We introduce an
approach to hybrid analog-digital audio processing using synthetic
impedance: digitally simulated circuit elements integrated into an
otherwise analog circuit. This approach combines the physicality and classic character of analog audio circuits alongside the
precision and flexibility of digital signal processing (DSP). Our
impedance synthesis system consists of a voltage-controlled current source and a microcontroller-based DSP system. We demonstrate our technique through modifying an iconic guitar distortion pedal, the Boss DS-1, showing the ability of the synthetic
impedance to both replicate and extend the behaviour of the pedal’s
diode clipping stage. We discuss the behaviour of the synthetic
impedance in isolated laboratory conditions and in the DS-1 pedal,
highlighting the technical and creative potential of the technique as
well as its practical limitations and future extensions.
Download RoomWeaver: A Digital Waveguide Mesh Based Room Acoustics Research Tool RoomWeaver is a Digital Waveguide Mesh (DWM) based Integrated Development Environment (IDE) style research tool, similar in appearance and functionality to other current acoustics software. The premise of RoomWeaver is to ease the development and application of DWM models for virtual acoustic spaces. This paper demonstrates the basic functionality of RoomWeaver’s 3D modelling and Room Impulse Response (RIR) generation capabilities. A case study is presented to show how new DWM types can be quickly developed and easily tested using RoomWeaver’s built in plug-in architecture through the implementation of a hybrid-type mesh. This hybrid mesh is comprised of efficient, yet geometrically inflexible, finite difference DWM elements and the geometrically versatile, but slow, wave-based DWM elements. The two types of DWM are interfaced using a KW-pipe and this hybrid model exhibits a significant increase in execution speed and a smaller memory footprint than standard wave-based DWM models and allows nontrivial geometries to be successfully modelled.
Download Digital Waveguide Mesh Modeling of Room Acoustics: Improved Anechoic Boundaries Digital waveguide mesh structures have proved useful in a wide variety of modelling applications. When modelling the acoustics of an enclosed space the accurate simulation of specific boundary conditions is paramount but waveguide mesh related techniques have as yet to provide an appropriate and reliable solution. This paper gives an overview of boundary types that have been implemented by researchers to date and describes the application of a higher order approximation for the particular case of an anechoic boundary, that may prove useful as part of a more general solution.