Sound Synthesis Research Articles

Perceptual evaluation of sound synthesis of wind turbine noise

This study brings together several laboratories with the aim of assessing the health effects of "audible" noise (> 20 Hz) and infrasound (< 20 Hz) emitted by wind turbines. To study loudness and annoyance due to this noise, perceptual tests are planned at the LMA, where a restitution cabin has been developed, specifically designed to diffuse very low frequencies and infrasound. As recording wind turbine noise is only possible at low wind speeds for a good quality sound reproduction, it would be interesting to be able to use sound synthesis of wind turbine noise. From sounds recorded in a wind farm for different meteorological conditions, the corresponding sounds have been synthesized. A physical model synthesis was performed, based on an extended-source aeroacoustic model taking into account propagation over flat ground. Dissimilarity tests including recorded and synthesized sounds enabled a 2D perceptual space to be built. Synthesized and the corresponding recorded sounds are closed together in the perceptual space, but some differences can be perceived, mainly due to difference in amplitude of fluctuation and spectral balance. The analysis of the perceptual space opens up interesting prospects for improving the sound synthesis and its use for future perceptual tests.

Methodology for 3D sound synthesis of directional acoustic sources by higher-order ambisonics

This paper presents the 3D sound field synthesis using both the multimodal method and higher-order ambisonics (HOA) of the pressure field radiated by directional acoustic sources. Ambisonics is a technique for encoding and reproducing measured or modeled (virtual) sound pressure field, based on a decomposition of the acoustic field over spherical harmonics. The directional source considered in this work is an acoustic horn excited by a flat piston. The free-field radiation from this horn is first modeled accurately over a wide frequency range using the multimodal method, which requires relatively low computational resources. This radiated pressure field, collected on a dual-layer sphere of virtual sensors distributed over a Lebedev geometry, allows its projection into the ambisonic domain. The pressure field is then synthetized in the laboratory's 3D 5th order HOA spatialization sphere, which consists of fifty-six loudspeakers. This offers the ability of listening to the radiated sound using a higher-order ambisonic synthesis of a 'virtual' source before it is manufactured. To qualitatively evaluate the performance of the proposed procedure, the transfer function of the synthesized horn is measured around the listening point within the spatialization sphere. Key words : 3D sound synthesis, high-order ambisonics, directive sources, waveguides, horn, multimodal method

Sound synthesis of geometric and material changes in archtop guitars: towards the timbral design of musical instruments

Through computer simulations and synthesis, our research studies the impact of various geometric and material modifications on archtop guitar sound. We use an accurate and realistic physical guitar model from which the bridge admittance and radiated sound pressure are computed. Subsequently, we synthesise the sound of this instrument via state-of-the-art methods for two different chords. The generated sound is then analysed in terms of traditional timbral descriptors. With this framework, it is possible to hear the design changes that the maker can perform in a guitar, paving the way for its timbral design, and bridging the gap between physical models and perception of sounds in musical instruments.

Sound prediction of an electric car using numerical simulation and sound synthesis techniques

The automotive industry's transition to electrification raises new challenges to maintain a comfortable acoustics environment both inside and outside the car. This paper presents an innovative way to make an early prediction of the overall sound of a vehicle at driver's ear by mixing noise sources that can be simulated and noise sources measured at component level. This hybrid approach combining Test and Simulation data helps define acoustic and vibration specifications at component level and take decisions on design strategies. For instance, the mounting method of the Electric motor to the body can be decided using a combination of Electric motor numerical simulation and Rolling noise sound synthesis techniques. Realistic signals could be generated and compared with sound quality metrics to choose the best vibration isolation strategy.

Measurements on the effect of vertical plucking angle of the kantele string

When a string instrument is plucked by hand, the player has the control over the plucking angle and the plucking position to influence the timbre. Different plucking angles will excite the vibrational modes of the strings differently. We designed a measurement rig to vary the vertical plucking angle in a controlled manner. We measured four different plucking angles at three different plucking positions with the copper wire excitation method on the Finnish eleven-string kantele. The results show that the beating phenomenon of the string partials depends on the plucking angle. The results can be used for example for sound synthesis purposes.

An efficient technique for developing the active sound control system in electric vehicle

The sound characteristic is a critical metric to manifest the brand differentiation of electric vehicle (EV), and the sound design with more diverse acoustic characteristics has become a hot issue in current research of EV technology. In this paper, an efficient technique of active sound design (ASD) is explored to develop the control system of active sound generation (ASG) with powerful sound quality for EV. Firstly, an optimization algorithm of sound synthesis based on multi-frequency superimposition is proposed to improve the harmonic interference phenomenon in the synthesized sounds. Subsequently, an adaptive sound control strategy is formulated, where an iterative accumulation method is proposed to calculate the “virtual engine speed” of EV, and a gain table is presented to divide the running state. Besides, an ASG system is developed based on the proposed ASD technique. The tests result demonstrate that there are 18 target order sounds are reproduced perfectly, and the powerful sound quality interior EV is enhanced while the original interior acoustic environment of EV is retained, which confirms the effectiveness of the proposed control technique of ASG system. The proposed ASD technique here accelerates the change from silence to sound quality in the electric vehicles, which has important theoretical significance and engineering value.

A simplified and controllable model of mode coupling for addressing nonlinear phenomena in sound synthesis processes

This paper introduces a simplified and controllable model for mode coupling in the context of modal synthesis. The model employs efficient coupled filters for sound synthesis purposes, intended to emulate the generation of sounds radiated by sources under strongly nonlinear conditions. Such filters generate tonal components in an interdependent way and are intended to emulate realistic perceptually salient effects in musical instruments in an efficient manner. The control of energy transfer between the filters is realized through a coupling matrix. The generation of prototypical sounds corresponding to nonlinear sources with the filter bank is presented. In particular, examples are proposed to generate sounds corresponding to impacts on thin structures and to the perturbation of the vibration of objects when it collides with an other object. The sound examples presented in the paper and available for listening on the accompanying site illustrate that a simple control of the input parameters allows the generation of sounds whose evocation is coherent and that the addition of random processes yields a significant improvement to the realism of the generated sounds.

Efficient Velvet-Noise Convolution in Multicore Processors

Velvet noise, a sparse pseudo-random signal, finds valuable applications in audio engineering, such as artificial reverberation, decorrelation filtering, and sound synthesis. These applications rely on convolution operations whose computational requirements depend on the length, sparsity, and bit resolution of the velvet-noise sequence used as filter coefficients. Given the inherent sparsity of velvet noise and its occasional restriction to a few distinct values, significant computational savings can be achieved by designing convolution algorithms that exploit these unique properties. This paper shows that an algorithm called the transposed double-vector filter is the most efficient way of convolving velvet noise with an audio signal. This method optimizes access patterns to take advantage of the processor’s fast caches. The sequential sparse algorithm is shown to be always faster than the dense one, and the speedup is linearly dependent on sparsity. The paper also explores the potential for further speedup on multicore platforms through parallelism and evaluate the impact of data encoding, including 16-bit and 32-bit integers and 32-bit floating-point representations. The results show that using the fastest implementation of a long velvet-noise filter, it is possible to process more than 40 channels of audio in real time using the quad-core processor of a modern system-on-chip.

Spatial Audio and Parameter Mapping Experiments for the Auditory Display of Coral Bleaching Data

In this article, data relating to Hawaii’s 2019 coral bleaching are auditorily displayed using parameter mapping sonification and ambisonics. Although primarily an explorative endeavor, this undertaking is conceptually rooted in ecological sound art and neutrally positioned on an established Cartesian framework known as Aesthetic Perspective Space. Through iterative design, different versions are implemented using sound surrogates of coral reefs’ natural soundscapes derived from either (a) real undersea recordings of reef environments or (b) modeling via means of sound synthesis. These audio surrogates correspond to data clusters aggregated by geographical location and, after being represented as sound sources on an ambisonic sphere, all contribute to a final sonic environment in which each cluster is progressively altered as the corresponding coral location undergoes bleaching. To assess both the perceived aesthetic placement of these experiments and their potential for public engagement in the discourse around climate change, evaluation studies are carried out. Results align with the aesthetic goals of the author, while consecutive versions manage to improve on critical fronts relating to climate awareness, providing further motivation toward more immersive implementations in future editions to come.

Synthesis of natural sound based on Nyquist

In recent years, sound synthesis has become an important part of daily life with the rapid development of the technology. There are many methods of natural sound synthesis, but each of them has its disadvantages. This paper explored a novel method of natural sound synthesis based on Nyquist. This method has significant advantages in high speed, convenience, flexibility, randomness, and small file size. The research investigates the effectiveness of this method by synthesizing four distinct natural sounds - rain, wind, thunder, and a combination of all three - using unit generators in Nyquist. To further evaluate the result, Mel spectrograms and a questionnaire are applied. The evaluation shows that the synthesized sounds meet expectations and are relatively real and natural. This method can be combined with other technology, such as the large language model, to provide better accessibility. This method can generate natural sounds for many tasks, especially those requiring high speed.

Analysis of dreamcore music composing based on Nyquist

As a matter of fact, computer music composition serves as a potent tool for musicians in the process of sound synthesis. More of their ideas and imaginations can be realized, more innovative exploration could be fostered in the field of music. Dreamcore is an art style that presents a kind of surreal nostalgia, and dreamcore music is a relatively new musical style related to the feeling of dreamcore. Being attracted by this musical style, the author aimed to compose a piece of dreamcore music by Nyquist, which is an interactive language for music composition. After summarizing and imitating the music styles and characteristics of the selected sample music, this study used the score, code it in Nyquist, and use musical effects to create a piece of music that is dreamy. The research obtained a music demo after the composition. The piece of music did embody the dreamcore aesthetic, and the basic requirements that the author made were met, but further exploration and enhancement could still be done to the music.

NeuralPMG: A Neural Polyphonic Music Generation System Based on Machine Learning Algorithms

The realm of music composition, augmented by technological advancements such as computers and related equipment, has undergone significant evolution since the 1970s. In the field algorithmic composition, however, the incorporation of artificial intelligence (AI) in sound generation and combination has been limited. Existing approaches predominantly emphasize sound synthesis techniques, with no music composition systems currently employing Nicolas Slonimsky’s theoretical framework. This article introduce NeuralPMG, a computer-assisted polyphonic music generation framework based on a Leap Motion (LM) device, machine learning (ML) algorithms, and brain-computer interface (BCI). ML algorithms are employed to classify user’s mental states into two categories: focused and relaxed. Interaction with the LM device allows users to define a melodic pattern, which is elaborated in conjunction with the user’s mental state as detected by the BCI to generate polyphonic music. NeuralPMG was evaluated through a user study that involved 19 students of Electronic Music Laboratory at a music conservatory, all of whom are active in the music composition field. The study encompassed a comprehensive analysis of participant interaction with NeuralPMG. The compositions they created during the study were also evaluated by two domain experts who addressed their aesthetics, innovativeness, elaboration level, practical applicability, and emotional impact. The findings indicate that NeuralPMG represents a promising tool, offering a simplified and expedited approach to music composition, and thus represents a valuable contribution to the field of algorithmic music composition.

Audio Recognition of the Percussion Sounds Generated by a 3D Auto-Drum Machine System via Machine Learning

Audio Recognition of the Percussion Sounds Generated by a 3D Auto-Drum Machine System via Machine Learning

Harmonizing Innovation: A Journey through the History of Computational Music

The history of computational music traces a fascinating journey of innovation and creativity, intertwining disciplines such as computer science, mathematics, music theory, and psychology. From its inception in the mid-20th century to its current state of sophistication, computational music has evolved into a multifaceted field encompassing algorithmic composition, digital signal processing, machine learning, and interactive music systems. Pioneering works such as Roads' "The Computer Music Tutorial" and Biles' "GenJam" exemplify the early endeavors in digital sound synthesis and algorithmic composition. The roots of computational music extend back to the 1950s and 1960s with the pioneering efforts of Max Mathews, John Chowning, and Lejaren Hiller, laying the groundwork for future advancements. Technological breakthroughs in the 1970s and 1980s, including the advent of digital audio workstations and FM synthesis, further propelled the field forward. The 1990s and 2000s witnessed democratization and accessibility with the rise of affordable software tools and online collaboration platforms. Today, computational music continues to evolve with the emergence of deep learning and generative AI techniques, albeit accompanied by ethical considerations regarding copyright ownership and algorithmic bias. In conclusion, the history of computational music underscores the transformative power of technology in shaping musical expression and invites us to explore new frontiers where creativity knows no bounds.

Estimation of acoustical materials sound absorption coefficient under oblique incidence plane wave and diffuse field via Allard model inversion

A technique for estimating the sound absorption of materials under oblique incidence plane wave and diffuse field excitations is proposed. It requires a mobile loudspeaker and a pair of fixed microphones above a layer of absorbing material. Starting from sound pressure measurements made above the material surface for multiple source positions and by inverting Allard’s propagation model, the proposed method allows for the identification of two effective (or equivalent) parameters, namely, the complex effective density and the complex wave number. Obtaining these parameters makes it possible to estimate the sound absorption coefficient for a plane wave with any angle of incidence or under a diffuse acoustic field by summation over the angles. The results are compared to theoretical values calculated using the Johnson-Champoux-Allard model and to reference measurements obtained using an impedance tube, a small cabin, a large reverberant room, and a sound field synthesis method. One of the limitations of this method lies in the assumptions associated with the Allard model to describe the sound field above the material (assumed to be isotropic, homogeneous, of constant thickness, and to behave like an equivalent fluid). The main advantages are (1) that the sound absorption coefficient can be estimated under oblique incidence plane wave and diffuse acoustic field with values that are always in a physical range (between 0 and 1), and (2) that samples of the order of the square meter without specific preparation can be tested which reduces the constraints associated with impedance tube or reverberant room measurements.

Research in the Department of Music Technology and Acoustics of the Hellenic Mediterranean University: An Overview and Prospects

The Department of Music Technology and Acoustics of the Hellenic Mediterranean University offers a unique higher education program in Greece, addressing the growing demand for specialists in music technology, sound technology, and acoustics. It aims to educate specialized professionals in the rapidly advancing scientific fields of music technology and acoustics, mainly driven by the swift progress in electronic technology. The Department aims to address a gap in the professional market by producing highly skilled graduates, capable not only of keeping up with the latest scientific and technological developments but also of leading the way by introducing innovative approaches and methods. The Department combines art, science, and technology, focusing on sound recording, analysis, synthesis, and music production. Music technology encompasses various cutting-edge fields such as network music performance, artificial intelligence in music, and music embodiment. Acoustics refers to fundamental aspects of sound as well as its generation, transmission, and related phenomena. It includes research fields such as physical acoustics, optoacoustics, and vibroacoustics. This overview presents the research activities, methodologies, and results. A discussion of future research works and pointers to future technological evolution towards real-world music and acoustics applications is also provided.

A comparison of modeled and measured impedance of brass instruments and mouthpieces

The impedance of a brass instrument has an important influence on its playability and sound timbre. The geometry of the mouthpiece has various features, such as the cup volume and shape, opening diameter, and length, that determine the characteristics of the overall impedance of the instrument-mouthpiece combination. Brass instruments, and especially mouthpieces, are designed for specific purposes, and horns or mouthpieces are chosen depending on the musical requirements. In order to investigate the relationship between the physical parameters and the impedances of instruments and mouthpieces, they have been modeled with transfer matrix and finite element model techniques, and the results are compared with impedance measurements of instruments, mouthpieces, and combinations of instruments and mouthpieces. Trumpets, flugelhorns, (French) horns, trombones, and the corresponding mouthpieces have been used. A detailed analysis of the estimation of the viscothermal losses has been performed, as the loss estimation in the narrow throat of the mouthpiece and in the flaring part of the brass instrument bell departs from the ordinary transfer matrix calculations. The effect of varying the physical parameters of mouthpieces and instruments is investigated by means of impedance considerations and sound synthesis, and the resulting influences on intonation, playability, and timbre are presented.

Overview of the technical area in musical acoustics

Musical acoustics was launched as one of the first Technical Committees of the Acoustical Society of America. The Technical Committee in Musical Acoustics (TCMU) is concerned with applying science and technology to the field of music. The four main areas are (1) physics of musical sound production in musical instruments and the voice, (2) music perception and cognition, (3) analysis and synthesis of musical sounds and compositions, and (4) recording and reproduction technology. The scopes of areas have changed over time; for example, current interests in using groundbreaking methods in artificial intelligence and computational acoustics to solve problems. There is substantial interdisciplinary overlap with other technical committees, such as Architectural Acoustics and Physiological and Psychological Acoustics. Musical acoustic studies sometimes only require relatively moderate equipment. Thus, they lend themselves well as a research entry point for undergraduate and even high school students—especially since there is often a natural interest in music from early on. However, research in the field can also become very complex and often requires cultural understanding and listening skills to interpret technical results and direct research meaningfully. On the practical side, the TCMU sometimes organizes concerts to augment the technical sessions.

Electronic wind instruments for mobility-restricted musicians

One of the earliest applications of analog music synthesizers was the simulation of orchestral instruments. Electronic wind instrument sounds were played through piano-like keyboards or interfaces with breath controllers that mimicked physical wind instruments. Synthesizers are also often the best alternative for artists with disabilities to play a musical instrument. This talk focuses on methods and experiences the authors were involved with to design electronic alternatives to wind instruments for people who lost control of their arms. The Jamboxx is a USB controller that was specifically designed as a head-only interface using a breath controller to simulate airflow but also operates as a suck/puff device to activate menus and buttons, a slider to manipulate pitch, and a tilt-sensor to control expression parameters. The Jamboxx also addressed musicians seeking a harmonica-type interface to augment their guitar performance. The AUMI instrument is a touchless device based on camera tracking. This talk will address different sound synthesis methods to achieve realistic wind instruments, the ability to integrate these instruments with other off-the-shelf products (e.g., VST plugins), and special requirements for artists with special needs to play these instruments without too much fatigue. [Work supported by the Craig H. Neilsen Foundation.]

Sound synthesis applications using a physical model of a single-reed woodwind instrument

Physical modeling can be used to analyze and predict the vibrations of a musical instrument. This also enables to numerically synthesize sounds as if they were produced by a real instrument. Focusing on single-reed woodwind instruments, a physical model should incorporate the actions of the player in order to synthesize realistic sounds. This interaction mostly takes place at the instrument mouthpiece—toneholes opened by the player's fingers may be approximated by changing the instrument geometry. A physical model is presented that is able to take embouchure effects into account, in order to reliably simulate note transitions. Regarding physical modeling synthesis, the numerical efficiency of the underlying algorithms should also be considered. Capturing as many physical phenomena as possible may lead to models that require longer running times. Omitting less significant phenomena may lead to models suitable for real-time performance, while retaining most of the sound characteristics of the real instrument. In either case, it is of utmost importance to prove that the simulation algorithms are numerically stable. Sound examples are presented in an attempt to imitate real recordings, as well as in a live performance setting (examples available at https://iwk.mdw.ac.at/sound-synthesis/)