Sound Synthesis Method Research Articles

Numerical Comparison of Different Equivalent Source Models and Source Quantification Techniques for Use in Sound Synthesis Systems

The aim of sound synthesis methods is to auralize the sound of a physical sound source in the way it is perceived by a listener at a particular location. Most existing synthesis methods start with a source - transmission path -receiver (s-t-r) model to predict spectral characteristics of the sound at the receiver location (e.g. a time-frequency spectrum). To define such a s-t-r model, an adequate representation of the physical sound source is crucial for achieving high quality sound syntheses. In the mid-frequency range, equivalent source models composed of a limited number of elementary substitute sources are usually applied. These equivalent models overcome many of the disadvantages of other sound source reconstruction models. However, quantification of the elementary substitute sources is difficult. After propagation along the transmission path and based upon the predicted spectral characteristics, the sound synthesis methods then synthesize an audible sound at the receiver location. This paper presents a numerical study on the performance of different equivalent source models and quantification techniques. It is shown that the recently developed inverse quantification approach based on acoustic particle velocities can be a fast and sufficient accurate alternative for techniques based on velocity and acceleration on the source surface or on acoustic pressures at indicator positions around the source. Furthermore, guidelines are given to select the number of equivalent substitute sources.

Feedback Amplitude Modulation Synthesis

A recently rediscovered sound synthesis method, which is based on feedback amplitude modulation (FBAM), is investigated. The FBAM system is interpreted as a periodically linear time-varying digital filter, and its stability, aliasing, and scaling properties are considered. Several novel variations of the basic system are derived and analyzed. Separation of the input and the modulation signals in FBAM structures is proposed which helps to create modular sound synthesis and digital audio effects applications. The FBAM is shown to be a powerful and versatile sound synthesis principle, which has similarities to the established distortion synthesis methods, but which is also essentially different from them.

Time–Frequency Synthesis of Noisy Sounds With Narrow Spectral Components

The inverse fast Fourier transform (FFT) method was proposed to alleviate the computational complexity of the additive sound synthesis method in real-time applications, and consists in synthesizing...

Design of a Scalable and Programmable Sound Synthesizer

Sound synthesis employed in many multimedia systems is a useful method to generate the sound of musical instruments. Although it has a long history of development, a few researches have been devoted to deriving efficient VLSI architectures. In this paper, we analyze the inherent dataflow of sound synthesis methods and propose a programmable VLSI architecture suitable for a scalable sound synthesizer. The sound quality and the level of polyphony can be enhanced only by increasing the operating speed and enlarging the memory. A fully integrated sound synthesis system is implemented as a prototype to verify the proposed architecture. The prototype chip fabricated in a 0.18- m CMOS process occupies 1.5 mm 1.5 mm, and can synthesize a 64-polyphonic sound in real time. The power consumption ranges from 2.05 to 13.8 mW depending on the level of polyphony and the sound quality.

Time–Frequency Synthesis of Noisy Sounds With Narrow Spectral Components

The inverse fast Fourier transform (FFT) method was proposed to alleviate the computational complexity of the additive sound synthesis method in real-time applications, and consists in synthesizing overlapping blocks of samples in the frequency domain. However, its application is limited by its inherent tradeoff between time and frequency resolution. In this paper, we propose an alternative to the inverse FFT method for synthesizing colored noise. The proposed approach uses subband signal processing to generate time-frequency noise with an autocorrelation function such that the noise obtained after converting it to time domain has the desired power spectral density. We show that the inverse FFT method can be interpreted as a particular case of the proposed method, and therefore, the latter offers some extra design flexibility. Exploiting this property, we present experimental results showing that the proposed method can offer a better tradeoff between time and frequency resolution, at the expense of some extra computations.

Extending the KLANGPILOT Score Language for Real-Time Notation

The original version of the KLANGPILOT notation environment was developed in LISP in 1992, with the purpose of generating Csound scores while allowing more sophisticated control of sound synthesis. It was a text-based, human-readable score language that described musical ideas in a way better suited to the creative process of composition. This language was then translated by the computer into detailed parameters for various sound-synthesis methods. As faster computers became available, a new real-time version of KLANGPILOT was developed that aimed to provide a highly intuitive and interactive user interface for entering, editing and displaying sound including timbral parameters. This article focuses on KLANGPILOT's engine for musical representation in real-time and shows basic concepts of a real-time graphical paradigm of sound representation within the Max/MSP programming environment.

Soundscape Design Through Evolutionary Engines

Abstract Two implementations of an Evolutionary Sound Synthesis method using the Interaural Time Difference (ITD) and psychoacoustic descriptors are presented here as a way to develop criteria for fitness evaluation. We also explore a relationship between adaptive sound evolution and three soundscape characteristics: keysounds, key-signals and sound-marks. Sonic Localization Field is defined using a sound attenuation factor and ITD azimuth angle, respectively (Ii, Li). These pairs are used to build Spatial Sound Genotypes (SSG) and they are extracted from a waveform population set. An explanation on how our model was initially written in MATLAB is followed by a recent Pure Data (Pd) implementation. It also elucidates the development and use of: parametric scores, a triplet of psychoacoustic descriptors and the correspondent graphical user interface.

Soundscape design through evolutionary engines

Two implementations of an Evolutionary Sound Synthesis method using the Interaural Time Difference (ITD) and psychoacoustic descriptors are presented here as a way to develop criteria for fitness evaluation. We also explore a relationship between adaptive sound evolution and three soundscape characteristics: key-sounds, key-signals and sound-marks. Sonic Localization Field is defined using a sound attenuation factor and ITD azimuth angle, respectively (Ii, Li). These pairs are used to build Spatial Sound Genotypes (SSG) and they are extracted from a waveform population set. An explanation on how our model was initially written in MATLAB is followed by a recent Pure Data (Pd) implementation. It also elucidates the development and use of: parametric scores, a triplet of psychoacoustic descriptors and the correspondent graphical user interface.

A synthesis and analysis framework for wind instrument sounds based on the digital pulse forming principle

A digital real‐time‐capable analysis‐ and synthesis‐system for wind instrument sounds, based on the pulse forming theory, has been developed. The rediscovered model for the sound generating process of wind instruments rests upon the idea, that wind instrument sounds can basically be put down to its excitation impulses, which independently of the fundamental always behave according to the same principles. First realised in the analogue wind instrument synthesizer Realton Variophon (1975), the sound synthesis method has currently been transferred onto a digital platform [supported by the German Research Foundation]. Instrument specific algorithms control the pulse width and shape according to the applied pitch and dynamic values. That way subtle sound nuances that can be produced on acoustic wind instruments as well as real timbre modulation may be synthesized by just modifying a single parameter (i.e. breath pressure). In order to validate the performance of the developed framework, several perception experiments were conducted subsequently.

Block based physical modeling for virtual musical instruments

A variety of methods for physical modeling sound synthesis has been developed so far, mostly for single sound objects like strings, plates, etc. However, complex virtual musical instruments require not only advanced models but also methods for combining one or more sound objects with excitation mechanisms and resonating structures. This presentation shows how to derive modeling blocks from basic physical laws and how to connect them in a physically meaningful way. The first step is to establish a physical model of a dynamical structure in terms of potential and flow variables, like force and velocity. It is important to observe also the boundary conditions because firstly they shape the spectrum of the vibrating structure and thus the timbre of the sound and secondly they determine the exchange of energy with the environment. The second step is the discretization of the physical model. This procedure is shown for the functional transformation method, which delivers discrete‐time models with direct access to the parameters of the physical model and which reproduces the original sound spectrum. In the last step, the resulting modeling blocks are connected by scattering elements which reflect energy back into the model or transmit it to neighboring blocks.

Model-based synthesis of aircraft noise to quantify human perception of sound quality and annoyance

This paper presents a method to synthesize aircraft noise as perceived on the ground. The developed method gives designers the opportunity to make a quick and economic evaluation concerning sound quality of different design alternatives or improvements on existing aircraft. By presenting several synthesized sounds to a jury, it is possible to evaluate the quality of different aircraft sounds and to construct a sound that can serve as a target for future aircraft designs. The combination of using a sound synthesis method that can perform changes to a recorded aircraft sound together with executing jury tests allows to quantify the human perception of aircraft noise.

Corpus-Based Concatenative Synthesis

Corpus-based concatenative methods for musical sound synthesis have attracted much attention recently. They make use of a variety of sound snippets in a database to assemble a desired sound or phrase according to a target specification given in sound descriptors or by an example sound. With ever-larger sound databases easily available, together with a pertinent description of their contents, they are increasingly used for composition, high-level instrument synthesis, and interactive exploration of a sound corpus. This article gives an overview of the components needed for corpus-based concatenative synthesis and details of some realizations. Signal processing methods are crucial for all parts of analysis, (segmentation; and descriptor analysis), for synthesis, and can intervene in the selection part, e.g., for spectral matching

Synthetic percussion

The widespread availability of fast small computers has removed many of the restrictions that governed the development of sound synthesis methods in the past, and, in particular, those based on physical modeling of musical instruments. Even relatively complex models can now produce sound output in something approaching real time, if not real time itself. As an example, various models of strings and 2-D percussion instruments, simulated using direct time domain methods, are presented here. Various issues are discussed, including interconnections of various vibrating objects, extensions of percussion instruments involving acoustic ‘‘preparation,’’ the modeling of nonlinearities, multichannel output, algorithmic complexity, and operation counts, as well as current work towards developing real time implementations. Sound examples are presented.

Conservative numerical methods for sound synthesis

Direct numerical simulation techniques, such as finite difference and finite element methods, are playing an increasingly important role in sound synthesis based on physical models of musical instruments. While they can lead to enormous improvements in sound quality over existing methods, a problem of mounting importance is that of maintaining numerical stability when the system to be simulated is strongly nonlinear, as is the case for many musical instruments. This problem is especially acute if real‐time synthesis is to be an eventual goal. Standard stability checking machinery, such as frequency domain (von Neumann) analysis, does not immediately apply, and, often, the most straightforward numerical methods may exhibit such instabilities in an unpredictable manner. In this paper, various techniques for the construction and analysis of numerical methods for strongly nonlinear musical systems are presented; they are based on the translation of the principle of conservation or dissipation of energy to discrete time and can lead directly to sufficient nonlinear stability conditions, without invoking frequency domain concepts. Special attention is paid to the nonlinear string, bar, and plate models. Numerical results and sound examples will be presented.

Concatenative sound synthesis: The early years

Concatenative sound synthesis is a promising method of musical sound synthesis with a steady stream of work and publications for over five years now. This article offers a comparative survey and taxonomy of the many different approaches to concatenative synthesis throughout the history of electronic music, starting in the 1950s, even if they weren't known as such at their time, up to the recent surge of contemporary methods. Concatenative sound synthesis methods use a large database of source sounds, segmented into units, and a unit selection algorithm that finds the units that match best the sound or musical phrase to be synthesized, called the target. The selection is performed according to the descriptors of the units. These are characteristics extracted from the source sounds, e.g. pitch, or attributed to them, e.g. instrument class. The selected units are then transformed to fully match the target specification, and concatenated. However, if the database is sufficiently large, the probability is high that a matching unit will be found, so the need to apply transformations is reduced. The most urgent and interesting problems for further work on concatenative synthesis are listed concerning segmentation, descriptors, efficiency, legality, data mining and real time interaction. Finally, the conclusion tries to provide some insight into the current and future state of concatenative synthesis research.

Music and science meet at the micro level: Time-frequency methods and granular synthesis

Musical research over the last century has become increasingly entwined with the areas of acoustics, psychoacoustics, and electroacoustics. One of the most striking results has been to push the frontiers of models of sound and music to the micro level, what is generally termed microsound. At this level, concepts of frequency and time are conjoined by a quantum relationship, with an uncertainty principle relating them that is precisely analogous to the more famous uncertainty principle of quantum physics. A class of methods of sound synthesis and signal processing known as time-frequency models have their basis at this quantum level such that changes in a signal’s time domain result in spectral alterations and vice versa. One such method, granular synthesis and the granulation of sampled sound, produces results by the generation of high densities of acoustical quanta called grains. Such a radical shift has profound implications for not only our models of sound design, but also for the compositional methods that emerge as well as the role of the composer in guiding complex processes. The paper will argue that these models are examples of a class of complex systems exhibiting emergent form that create a new form of virtual music instrument.

Iterative sound synthesis by means of cross-coupled digital oscillators

Musicians have long been interested in using iterative processes to aid the composition of musical forms (macrostructure) and to synthesize sounds (microstructure). This paper introduces a new sound synthesis method exploring the non-linear behaviour of two iterative cross-coupled digital oscillators. It begins with a brief introduction to iterative systems followed by background information on previous attempts at using them for synthesizing sounds (e.g. feedback frequency and amplitude modulations). Next, it introduces our synthesis method and briefly explains how it has been implemented in a system for real-time composition and performance. The paper concludes with a discussion on how the system has been put into practice to compose and perform a number of works.

Gestural Control of Sound Synthesis

This paper provides a review of gestural control of sound synthesis in the context of the design and evaluation of digital musical instruments. It discusses research in various areas related to this field and equally focuses on four main topics: analysis of music performers' gestures, gestural capture technologies, real-time sound synthesis methods, and strategies for mapping gesture variables to sound synthesis input parameters. Finally, this approach is illustrated by presenting an application of this research to the control of digital audio effects.

Physically informed stochastic modal sound synthesis

A general and flexible sound synthesis method is described, which is based on controlled random excitations and parameter modifications of resonant filters. Parameters can be derived from simulations of particle/friction systems, from data extracted from physical experiments, from signal analysis (a developing yet still open topic of research), or from simple experimentation and ‘‘tweaking.’’ The algorithm has proven convincing and useful for modeling the sounds of many common objects and interactions in music and everyday life. Particle system examples include maracas, windchimes, coins in a pocket, ice cubes in a glass, shoveling gravel, breaking glass, etc. Friction systems include coins rolling along a table, squeaking floor panels and hinges, etc. Aside from being flexible and realistic, the algorithm is extremely efficient by nearly any standard of computation or memory use. Most exciting is the ability to drive and modify the parameters in real time, resulting in virtual objects and systems which are ‘‘playable’’ in musical performance, or easily useable for sound effects in games and virtual reality.

Synthesis for logical initializability of synchronous finite-state machines

Logical initializability is the property of a gate-level circuit whereby it can be driven to a unique start state when simulated by a three-valued (0, 1, X) simulator. In practice, commercial logic and fault simulators often require initialization under such a three-valued simulation model. In this paper, the first sound and systematic synthesis method is proposed to ensure the logical initializability of synchronous finite-state machines. The method includes both state assignment and combinational logic synthesis steps. It is shown that a previous approach to synthesis-for-initializability, which uses a constrained state assignment method, may produce uninitializable circuits. Here, a new state assignment method is proposed that is guaranteed correct. Furthermore, it is shown that combinational logic synthesis also has a direct impact on initializability; necessary and sufficient constraints on combinational logic synthesis are proposed to guarantee that the resulting gate-level circuits are logically initializable. The above two synthesis steps have been incorporated into a computer-aided design tool, SALSIFY, targeted to both two-level and multilevel implementations.