Download CONMOD: Controllable Neural Frame-Based Modulation Effects Deep learning models have seen widespread use in modelling LFOdriven audio effects, such as phaser and flanger. Although existing neural architectures exhibit high-quality emulation of individual effects, they do not possess the capability to manipulate the output via control parameters. To address this issue, we introduce Controllable Neural Frame-based Modulation Effects (CONMOD), a single black-box model which emulates various LFOdriven effects in a frame-wise manner, offering control over LFO frequency and feedback parameters. Additionally, the model is capable of learning the continuous embedding space of two distinct phaser effects, enabling us to steer between effects and achieve creative outputs. Our model outperforms previous work while possessing both controllability and universality, presenting opportunities to enhance creativity in modern LFO-driven audio effects. Additional demo of our model is available in the accompanying website.1
Download Harmonize-Decompose Audio Signals with Global Amplitude and Frequency Modulations A key building block in music transcription and indexing operations is the decomposition of music signals into notes. We model a note signal as a periodic signal with slow (frequency-selective) amplitude modulation and global frequency-warping. Global frequency-warping allows for an inharmonic frequency modulation, while the global amplitude modulation allows the various harmonics of the periodic signal to decay at different speeds. The global frequency-warping is achieved by a Laguerre transform (that has shown to fit stiffed strings inharmonic behavior). Assuming additive noise, the estimation of the model parameters and the optimization is performed in a Harmonize-Extract fashion. Simulations illustrate that the extraction technique oversteps the limitation of the global AM-FM representation and analysis techniques and allows the processing of inharmonic string instruments (e.g. piano).
Download Real-Time Virtual Analog Modelling of Diode-Based VCAs Some early analog voltage-controlled amplifiers (VCAs) utilized
semiconductor diodes as a variable-gain element. Diode-based
VCAs exhibit a unique sound quality, with distortion dependent
both on signal level and gain control. In this work, we examine the
behavior of a simplified circuit for a diode-based VCA and propose
a nonlinear, explicit, stateless digital model. This approach avoids
traditional iterative algorithms, which can be computationally intensive. The resulting digital model retains the sonic characteristics
of the analog model and is suitable for real-time simulation. We
present an analysis of the gain characteristics and harmonic distortion produced by this model, as well as practical guidance for
implementation. We apply this approach to a set of alternative
analog topologies and introduce a family of digital VCA models
based on fixed nonlinearities with variable operating points.
Download Effect of Latency on Playing Accuracy of Two Gesture Controlled Continuous Sound Instruments Without Tactile Feedback The paper reports results from an experimental study quantifying how latency affects the playing accuracy of two continuous sound instruments. 11 subjects played a conventional Theremin and a virtual reality Theremin. Both instruments provided the user only audio feedback. The subjects performed two tasks under different instrument latencies. They attempted to match the pitch of the instrument to a sample pitch and they played along a short sample melody and a metronome. Both the sample sound and the instrument’s sound were recorded on different channels of a sound file. Later the pitch of the sounds was extracted and user performance analyzed. The results show that the time required to match a given pitch degrades about five times the introduced latency suggesting that the feedback latency cumulates over the whole task. Errors while playing along a sample melody increased 80% by average on the highest latency of 240ms. Latencies until 120ms increased the errors only slightly.
Download Real-Time Dynamic Image-Source Implementation For Auralisation This paper describes a software package for auralisation in interactive virtual reality environments. Its purpose is to reproduce, in real time, the 3D soundfield within a virtual room where listener and sound sources can be moved freely. Output sound is presented binaurally using headphones. Auralisation is based on geometric acoustic models combined with head-related transfer functions (HRTFs): the direct sound and reflections from each source are computed dynamically by the image-source method. Directional cues are obtained by filtering these incoming sounds by the HRTFs corresponding to their propagation directions relative to the listener, computed on the basis of the information provided by a head-tracking device. Two interactive real-time applications were developed to demonstrate the operation of this software package. Both provide a visual representation of listener (position and head orientation) and sources (including image sources). One focusses on the auralisation-visualisation synchrony and the other on the dynamic calculation of reflection paths. Computational performance results of the auralisation system are presented.
Download Digitizing the Schumann PLL Analog Harmonizer The Schumann Electronics PLL is a guitar effect that uses hardwarebased processing of one-bit digital signals, with op-amp saturation and CMOS control systems used to generate multiple square waves derived from the frequency of the input signal. The effect may be simulated in the digital domain by cascading stages of statespace virtual analog modeling and algorithmic approximations of CMOS integrated circuits. Phase-locked loops, decade counters, and Schmitt trigger inverters are modeled using logic algorithms, allowing for the comparable digital implementation of the Schumann PLL. Simulation results are presented.
Download More Acoustic Sounding Timbre From Guitar Pickups Amplified guitars with pickups tend to sound ’dry’ and electric, whether the instrument is acoustic or electric. Vibration or pressure sensing pickups for acoustic guitars do not capture the body vibrations with fidelity and in the electric guitar with magnetic pickups there often is no resonating body at all. Especially with an acoustic guitar there is a need to reinforce the sound by retaining the natural acoustic timbre. In this study we have explored the use of DSP equalization to make the signal from the pickup sound more acoustic. Both acoustic and electric guitar pickups are studied. Different digital filters to simulate acoustic sound are compared, and related estimation techniques for filter parameters are discussed.
Download Spatial audio quality and user preference of listening systems in video games Spatial audio playback solutions provide video game players with ways to experience more immersive and engaging video game content. This paper aims to find whether listening systems that are able to more accurately convey spatial information are preferred by video game players, and to what extent this is true for different loudspeaker configurations whilst engaged in video game play. Results do suggest that a listening system with high perceived spatial quality is more preferred.