Download Unsupervised Taxonomy of Sound Effects Sound effect libraries are commonly used by sound designers in a range of industries. Taxonomies exist for the classification of sounds into groups based on subjective similarity, sound source or common environmental context. However, these taxonomies are not standardised, and no taxonomy based purely on the sonic properties of audio exists. We present a method using feature selection, unsupervised learning and hierarchical clustering to develop an unsupervised taxonomy of sound effects based entirely on the sonic properties of the audio within a sound effect library. The unsupervised taxonomy is then related back to the perceived meaning of the relevant audio features.
Download Is The Player More Influenced By The Auditory Than The Tactile Feedback From The Instrument? What sensory feedback, tactile or auditory, is the more important for a musician when playing? In an attempt to answer this question, subjects were asked to play along with a metronome while the auditory feedback from their playing was manipulated. The preliminary results showed a tendency for matching sound with sound, i.e. players initiated strokes earlier as the delay increased. Increase in timing errors indicate a possible breakpoint around 55 ms. As the feedback was delayed even more subjects showed increased difficulties in maintaining a steady rhythm.
Download Fast Approximation of the Lambert W Function for Virtual Analog Modelling When modelling circuits one has often to deal with equations containing both a linear and an exponential part. If only a single exponential term is present or predominant, exact or approximate closed-form solutions can be found in terms of the Lambert W function. In this paper, we propose reformulating such expressions in terms of the Wright Omega function when specific conditions are met that are customary in practical cases of interest. This eliminates the need to compute an exponential term at audio rate. Moreover, we propose simple and real-time suitable approximations of the Omega function. We apply our approach to a static and a dynamic nonlinear system, obtaining digital models that have high accuracy, low computational cost, and are stable in all conditions, making the proposed method suitable for virtual analog modelling of circuits containing semiconductor devices.
Download Joint modeling of impedance and radiation as a recursive parallel filter structure for efficient synthesis of wind instrument sound In the context of efficient synthesis of wind instrument sound, we introduce a technique for joint modeling of input impedance and sound pressure radiation as digital filters in parallel form, with the filter coefficients derived from experimental data. In a series of laboratory measurements taken on an alto saxophone, the input impedance and sound pressure radiation responses were obtained for each fingering. In a first analysis step, we iteratively minimize the error between the frequency response of an input impedance measurement and that of a digital impedance model constructed from a parallel filter structure akin to the discretization of a modal expansion. With the modal coefficients in hand, we propose a digital model for sound pressure radiation which relies on the same parallel structure, thus suitable for coefficient estimation via frequency-domain least-squares. For modeling the transition between fingering positions, we propose a simple model based on linear interpolation of input impedance and sound pressure radiation models. For efficient sound synthesis, the common impedance-radiation model is used to construct a joint reflectanceradiation digital filter realized as a digital waveguide termination that is interfaced to a reed model based on nonlinear scattering.
Download Modal Spring Reverb Based on Discretisation of the Thin Helical Spring Model The distributed nature of coupling in helical springs presents specific challenges in obtaining efficient computational structures
for accurate spring reverb simulation. For direct simulation approaches, such as finite-difference methods, this is typically manifested in significant numerical dispersion within the hearing range.
Building on a recent study of a simpler spring model, this paper presents an alternative discretisation approach that employs
higher-order spatial approximations and applies centred stencils at
the boundaries to address the underlying linear-system eigenvalue
problem. Temporal discretisation is then applied to the resultant
uncoupled mode system, rendering an efficient and flexible modal
reverb structure. Through dispersion analysis it is shown that numerical dispersion errors can be kept extremely small across the
hearing range for a relatively low number of system nodes. Analysis of an impulse response simulated using model parameters calculated from a measured spring geometry confirms that the model
captures an enhanced set of spring characteristics.
Download Feature Based Delay Line Using Real-Time Concatenative Synthesis In this paper we introduce a novel approach utilizing real-time concatenative synthesis to produce a Feature-Based Delay Line (FBDL). Expanding upon the concept of a traditional delay, its most basic function is familiar – a dry signal is copied to an audio buffer whose read position is time shifted producing a delayed or "wet" signal that is then remixed with the dry. In our implementation, however, the traditionally unaltered wet signal is modified such that the audio delay buffer is segmented and concatenated according to specific audio features. Specifically, the input audio is analyzed and segmented as it is written to the delay buffer, where delayed segments are matched to a target feature set, such that the most similar segments are selected to constitute the wet signal of the delay. Targeting methods, either manual or automated, can be used to explore the feature space of the delay line buffer based on dry signal feature information and relevant targeting parameters, such as delay time. This paper will outline our process, detailing important requirements such as targeting and considerations for feature extraction and concatenation synthesis, as well as discussing use cases, performance evaluation, and commentary on the potential of advances to digital delay lines.
Download Antiderivative Antialiasing for Stateful Systems Nonlinear systems, like e.g. guitar distortion effects, play an important role in musical signal processing. One major problem encountered in digital nonlinear systems is aliasing distortion. Consequently, various aliasing reduction methods have been proposed in the literature. One of these is based on using the antiderivative of the nonlinearity and has proven effective, but is limited to memoryless systems. In this work, it is extended to a class of stateful systems which includes but is not limited to systems with a single one-port nonlinearity. Two examples from the realm of virtual analog modeling show its applicability to and effectiveness for commonly encountered guitar distortion effect circuits.
Download Simulation of Fender Type Guitar Preamp using Approximation and State-Space Model This paper deals with usage of approximations for simulation of more complex audio circuits. A Fender type guitar preamp was chosen as a case study. This circuit contains two tubes and thus four nonlinear functions as well as it is a parametric circuit because of an integrated tone stack. A state-space approach was used for simulation and further, precomputed solution is approximated using nonuniform cubic splines.
Download A Wavelet-Based Method for the Estimation of Clarity of Attack Parameters in Non-Percussive Instruments From the exploration of databases of instrument sounds to the selfassisted practice of musical instruments, methods for automatically
and objectively assessing the quality of musical tones are in high
demand. In this paper, we develop a new algorithm for estimating
the duration of the attack, with particular attention to wind and
bowed string instruments. In fact, for these instruments, the quality
of the tones is highly influenced by the attack clarity, for which,
together with pitch stability, the attack duration is an indicator often
used by teachers by ear. Since the direct estimation of the attack
duration from sounds is made difficult by the initial preponderance of the excitation noise, we propose a more robust approach
based on the separation of the ensemble of the harmonics from the
excitation noise, which is obtained by means of an improved pitchsynchronous wavelet transform. We also define a new parameter,
the noise ducking time, which is relevant for detecting the extent of
the noise component in the attack. In addition to the exploration of
available sound databases, for testing our algorithm, we created an
annotated data set in which several problematic sounds are included.
Moreover, to check the consistency and robustness of our duration
estimates, we applied our algorithm to sets of synthetic sounds with
noisy attacks of programmable duration.
Download Virtual rooms recreation for Wave Field Synthesis Advanced multichannel sound systems such as Wave Field Synthesis (WFS) allow to recreate spatial wide sound scenes of sources. The recreation of the illusion of a 3D natural and realistic sound scene can be achieved by means of virtual rooms where the wave field is simulated. Such wave field is used as a source of information for the convolution of WFS sound sources with extrapolated impulsive responses in these virtual rooms. To obtain the needed plane waves for auralization, a complete description of the sound field is needed, including an accurate knowledge of the particle velocity. In this paper, virtual rooms are simulated by means of Finite-Differences Time Domain method. This method provides a complete solution of the sound field variables in a wide frequency band and can be used to produce both the impulsive responses of pressure and particle velocity for plane wave decomposition, prior to auralization. To illustrate its applicability, a set of rooms consisting of a typical auditorium room, a cinema and a perfect cube are shown and evaluated.