Sine Wave Synthesis Research Articles

Electrical Quantum Metrology Standard for the Synthesis of Ac Voltages

A prototype Josephson quantum standard for synthesizing sine waves characterised by low-level harmonics and high accuracy was developed, opening up new possibilities for metrological support in the area of ac voltage. The standard includes a cryogenic probe with Josephson chips, a delta-sigma modulator, a pulse pattern generator, a compensation circuit, a spectrum analyzer, a video control unit, as well as special software. A capability of sine wave synthesis with an output voltage up to 130 mV RMS over a wide frequency range from 1 kHz to 100 kHz is demonstrated. Higher harmonics are suppressed below the noise floor up to 100 dBc.

Specialized memory systems for learning spoken words.

Learning new words entails, inter alia, encoding of novel sound patterns and transferring those patterns from short-term to long-term memory. We report a series of 5 experiments that investigated whether the memory systems engaged in word learning are specialized for speech and whether utilization of these systems results in a benefit for word learning. Sine-wave synthesis (SWS) was applied to spoken nonwords, and listeners were or were not informed (through instruction and familiarization) that the SWS stimuli were derived from actual utterances. This allowed us to manipulate whether listeners would process sound sequences as speech or as nonspeech. In a sound-picture association learning task, listeners who processed the SWS stimuli as speech consistently learned faster and remembered more associations than listeners who processed the same stimuli as nonspeech. The advantage of listening in "speech mode" was stable over the course of 7 days. These results provide causal evidence that access to a specialized, phonological short-term memory system is important for word learning. More generally, this study supports the notion that subsystems of auditory short-term memory are specialized for processing different types of acoustic information. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Partial Dynamic Element Matching Technique for Digital-to-Analog Converters Used for Digital Harmonic-Cancelling Sine-Wave Synthesis

Digital harmonic-cancelling sine-wave synthesizers (DHSSs) use a 47 year old concept, recently revived as a power and area efficient solution for on-chip sine-wave synthesis. The operation of a DHSS involves amplitude scaling and summing a set of square-waves to produce a sampled sine-wave. The circuit which performs the scaling and summing operation is referred to as the harmonic-cancelling digital-to-analog converter (HC-DAC). Unlike a regular DAC whose amplitude weights are defined by powers of two, an HC-DAC's amplitude weights are defined by a sine function. Thus, HC-DACs present intriguing design problems which cannot be solved using the conventional knowledge gathered from designing regular DACs. One such problem is managing the effect of mismatch between unit-elements in HC-DACs. This paper proposes a partial dynamic element matching (DEM) technique tailored for HC-DACs, which reduces the effect of mismatch, while preserving the power and area efficiency of DHSSs. The effectiveness of the DEM technique is evaluated using a DHSS circuit fabricated in an STMicroelectronics 130 nm CMOS technology. Test results show that applying the DEM technique increased the figure-of-merit of the DHSS by 40% at 2 MHz output frequency.

Hierarchical Organization of Auditory and Motor Representations in Speech Perception: Evidence from Searchlight Similarity Analysis

How humans extract the identity of speech sounds from highly variable acoustic signals remains unclear. Here, we use searchlight representational similarity analysis (RSA) to localize and characterize neural representations of syllables at different levels of the hierarchically organized temporo-frontal pathways for speech perception. We asked participants to listen to spoken syllables that differed considerably in their surface acoustic form by changing speaker and degrading surface acoustics using noise-vocoding and sine wave synthesis while we recorded neural responses with functional magnetic resonance imaging. We found evidence for a graded hierarchy of abstraction across the brain. At the peak of the hierarchy, neural representations in somatomotor cortex encoded syllable identity but not surface acoustic form, at the base of the hierarchy, primary auditory cortex showed the reverse. In contrast, bilateral temporal cortex exhibited an intermediate response, encoding both syllable identity and the surface acoustic form of speech. Regions of somatomotor cortex associated with encoding syllable identity in perception were also engaged when producing the same syllables in a separate session. These findings are consistent with a hierarchical account of how variable acoustic signals are transformed into abstract representations of the identity of speech sounds.

Efficient Visual Search from Synchronized Auditory Signals Requires Transient Audiovisual Events

BackgroundA prevailing view is that audiovisual integration requires temporally coincident signals. However, a recent study failed to find any evidence for audiovisual integration in visual search even when using synchronized audiovisual events. An important question is what information is critical to observe audiovisual integration.Methodology/Principal FindingsHere we demonstrate that temporal coincidence (i.e., synchrony) of auditory and visual components can trigger audiovisual interaction in cluttered displays and consequently produce very fast and efficient target identification. In visual search experiments, subjects found a modulating visual target vastly more efficiently when it was paired with a synchronous auditory signal. By manipulating the kind of temporal modulation (sine wave vs. square wave vs. difference wave; harmonic sine-wave synthesis; gradient of onset/offset ramps) we show that abrupt visual events are required for this search efficiency to occur, and that sinusoidal audiovisual modulations do not support efficient search.Conclusions/SignificanceThus, audiovisual temporal alignment will only lead to benefits in visual search if the changes in the component signals are both synchronized and transient. We propose that transient signals are necessary in synchrony-driven binding to avoid spurious interactions with unrelated signals when these occur close together in time.

Asynchrony tolerance in the perceptual organization of speech

Researchers have claimed that listeners tolerate large temporal distortion when integrating the spectral components of speech. In some estimates, perceivers resolve linguistic attributes at spectral desynchronies as great as the duration of a syllable. We obtained new measures of perceptual tolerance of auditory asynchrony, using sine-wave synthesis in order to require perceivers to resolve the speech stream dynamically. Listeners transcribed sentences in which the tone analogue of a second formant was desynchronized relative to the remaining tones of a sentence, with desynchrony ranging from a 250-msec lead to a 250-msec lag. Intelligibility declined symmetrically from 72% at synchrony to 7% at +/-100 msec. This finding of narrow asynchrony tolerance indicates a time-critical feature of the auditory perceptual organization of speech.

Cross-linguistics differences in non-speech perception

This research explores listeners perception of non-speech stimuli across languages. We will report on two experiments conducted with the same stimuli. The stimuli were synthesized from naturally produced vowel-fricative-vowel sequences consisting the fricatives [f, th, s, sh, x, h], and the vowel environments [i—i, a—a, u—u]. The vowels were synthesized using sine wave synthesis and appended onto the natural fricative. Tokens will be presented to two groups of Dutch and English listeners over headphones with a 100 ms interval. Listeners will be told that the stimuli is non-speech. The first experiment is a simple AX discrimination task where the listener decides whether the tokens were same or different. The second experiment is a rating task where the listener is asked to rate the similarity of the two tokens on a five-point equal interval scale. It is predicted that results of both experiments will be the same for both groups of listeners. These results will be compared to the results of the same experiment with non-synthesized speech [K. Johnson and M. Babel, J. Acoust. Soc. Am. 120, 3292 (2006)]. [Work supported by the NIH.]

Direct AWG sine wave synthesis with fixed clock frequency

Direct generation of sinusoids using an arbitrary waveform generator is a common synthesis technique. Generating an arbitrary frequency has generally been implemented by synthesizing a master clock frequency with techniques, which can introduce jitter. A method of generating a frequency to an arbitrary accuracy using the mathematics of continuing fractions is described.

Some Design Concepts for Electrical Impedance Measurement

Abstract: Design concepts for the implementation of two basic functions for measurement of electrical impedance are presented: current injection and voltage measurement. At relatively high frequencies, the application of an alternating current through the body or a body segment results in electromagnetic stray fields that reduce the amount of current actually injected into the tissue under study. It is shown that electrical isolation and small dimensions of the isolated section are indispensable in order to substantially reduce these stray currents. The paper describes a new wideband current source configuration driven by direct digital sine wave synthesis (DDS) presenting very low stray currents due to a symmetrical layout. Two implementations of the actual current source circuit are presented: (1) a voltage‐controlled system and (2) a current conveyor‐based circuit.A wideband input amplifier with transformer coupling is described. The current source, amplifier, and (in case of tomography) multiplexer are also situated on an electrically isolated front end. The presented concepts are applied in a new electrical impedance tomograph (EIT) presently under construction in our department.

Speech encoding method, speech decoding method and speech encoding/decoding method

A speech encoding/decoding method calculates a short-term prediction error of an input speech signal that is divided on a time axis into blocks, represents the short-term prediction residue by a synthesized sine wave and a noise and encodes a frequency spectrum of each of the synthesized sine wave and the noise to encode the speech signal. The speech encoding/decoding method decodes the speech signal on a block basis and finds a short-term prediction residue waveform by sine wave synthesis and noise synthesis of the encoded speech signal. The speech encoding/decoding method then synthesizes the time-axis waveform signal based on the short-term prediction residue waveform of the encoded speech signal.

A New VLSI Implementation of Additive Synthesis

Additive sine-wave synthesis is one of the most powerful techniques available for sound generation. Its theoretical background dates back to the 19th century and the work of Frangois M. C. Fourier. Although any sound can be generated by the summation of an appropriate number of sine waves, the realization of complex real-time additive synthesis systems is difficult because of the large number of independent oscillators needed. Our first attempts to obtain a digital additive synthesis were carried out in the early 1970s with the TAU2 system (Bertini, Chimenti, and Denoth 1976), which consisted of a set of analog oscillators digitally controlled by a computer. The system's performance was meager by today's standards, but back then it was considered an interesting experiment that showed the power of such synthesis systems (Blum 1979). It is generally accepted that 30-100 partials are needed to generate an excellent sound, depending on the timbral characteristics (Moorer, Grey, Nad, and Strawn 1977; Comerford 1993), so it is evident that a polyphonic multitimbral synthesis will need several thousand sinusoids. The computational power required is huge, so that tens or even hundreds of powerful digital signal processors (DSPs) are needed if traditional methods are used. As a result, this technique is not widespread except in academic study, where it is studied in terms of analysis/decomposition/resynthesis (George and Smith 1992). In fact, working in the frequency domain, additive synthesis allows the management of sound characteristics in a direct and powerful way, which is attractive for the synthesis of new timbres or the modification and re-editing of existing ones. To make additive synthesis more affordable, it is strongly advisable to create an ad hoc structure, for example, an application-specific integrated circuit (ASIC) (Rodet 1996). This article describes a very large-scale integration (VLSI) implementation of additive synthesis by means of a novel system architecture that makes possible the realization of powerful ASIC solutions; the chip described permits the generation of 1,200 sinusoids in real time. The article reviews the vari-

A New Nonlinear Function Generation Technique for Sine Wave Synthesis

A new nonlinear function generation technique for sine wave synthesis, using operational amplifiers and the field effect transistor characteristics, is presented with symmetrical triangular wave as...

An ASIC for Digital Additive Sine-Wave Synthesis

In 1822 Frangois M. C. Fourier described how any signal may be broken down into an infinite series of appropriately weighted pure sine waves (Fourier 1955). Today this notion is central to many signalprocessing applications. It is the aim of the project described in this article to create a flexible and visual tool for analyzing, manipulating, and recreating using Fourier analysis coupled with additive sine-wave synthesis or ASWS. By applying Fourier theory, a sample may separated into a set of sine waves with time-function envelopes, and in this format many aspects of the can be readily visualized and thus intelligently manipulated. Figure 1 illustrates a typical sound generated in this way. This landscape has time, frequency, and amplitude on orthogonal axes, which is a very convenient format for describing a sound, since it bypasses many of the difficulties associated with raw sampled sound. For example, the sound's frequency can be modified quite independently of its time, and vice versa, without resorting to complex resampling algorithms. Filtering the requires nothing more than weighting the enveloped partial components, based on their frequency, and, perhaps, time. While the idea of creating by adding together sine waves is not in itself new, obstacles (encountered particularly in analysis) have hitherto prevented ASWS from providing a generalpurpose method for synthesis. Advancement of analysis techniques, coupled with hardware improvements, however, are starting to make ASWS an attractive alternative to more traditional soundsynthesis approaches (Brown 1991; Gambardella 1979). This article describes some of the design aspects that were considered during the development of the authors' ASWS engine, based on a custom application-specific integrated circuit (ASIC). The ASWS Engine

Multichannel Simultaneous Digital Tracking Filters for Swept-Sine Vibration Control

The digital control of swept sine-wave tests and the associated theory needed for swept sine-wave synthesis and analysis will be discussed. This type of testing requires that the digital vibration control system drive the actuator subsystem with an analog signal. This signal is a low-distortion sine wave with a smoothly varying frequency and amplitude. The testing also requires that the controller be able to measure the response of this type of excitation by way of a control transducer mounted at some chosen point on the device under test. This paper will concentrate on the details of output signal generation to enhance its accuracy and suitability for complex heterodyne generation. The complex heterodyne is used in conjunction with 0-Hz intermediate frequency detectors to implement a digital tracking filter. Digital low-pass filters are used to implement 0-Hz intermediate frequency detectors. The tracking filter is used for time-variable spectral analysis6 (i.e., determining the instantaneous complex amplitude of a sweeping sine wave as encounted in swept sine testing).

On the perceptual organization of speech.

A general account of auditory perceptual organization has developed in the past 2 decades. It relies on primitive devices akin to the Gestalt principles of organization to assign sensory elements to probable groupings and invokes secondary schematic processes to confirm or to repair the possible organization. Although this conceptualization is intended to apply universally, the variety and arrangement of acoustic constituents of speech violate Gestalt principles at numerous junctures, cohering perceptually, nonetheless. The authors report 3 experiments on organization in phonetic perception, using sine wave synthesis to evade the Gestalt rules and the schematic processes alike. These findings falsify a general auditory account, showing that phonetic perceptual organization is achieved by specific sensitivity to the acoustic modulations characteristic of speech signals.

Computationally efficient sine wave synthesis for acoustic waveform processing

Methods and apparatus for reducing discontinuities between frames of sinusoidally modeled acoustic waveforms, such as speech, which occur when sampling at low frame rates. A Fast Fourier Transform-based overlap-add technique is applied to amplitude, frequency and phase components of sinusoidal waves after frame-to-frame sine wave matching has been performed. Matched sine wave amplitudes and frequencies are linearly interpolated and mid-point phase is estimated such that the mid-frame sine wave is best fit to the most recent half-frame segments of the lagging and leading sine waves. Synthetic mid-frame sine waves are generated using the interpolated amplitude and frequency and estimated phase values. Synthesized acoustic waveforms of high quality from original source waveforms can be produced in sinusoidal analysis/synthesis operations at coding frame rates of 50 Hz and lower. The methods and devices disclosed herein are particularly useful for computationally efficient coding and synthesis of speech waveforms.

Perception of the rhythm of English and of nonspeech analogs

The results of Lehiste (1973, 1977) and of Donoran and Darwin (1979) suggest that English speech rhythm is perceived as isochronous, and that this percept is special to speech. Results of two experiments do not support these claims. In both experiments subjects tapped to the beat of LPC resynthesized sentences containing four stressed syllables, or to the beat of analogs of the sentences. In experiment I, which followed the Donovan and Darwin paradigm, the average responses were more nearly even than the interstress intervals of the sentences; on the other hand, more than half of the subjects responded with a rhythm that matched the sentence rhythm more closely than an isochronous one. In experiment II, subjects tapped to one of four versions of the sentence stimuli: (1) LPC resyntbesis; (2) LPC resynthesis with formant bandwidths broadened to 1000 Hz; or sine wave synthesis, either (3) cued as speech or (4) cued as nonspeech. If there is a perceptual effect specific to speech, subjects hearing the speech‐cued sine wave versions would tap more evenly than the subjects hearing the nonspeech‐cued versions. The opposite effect was in fact found. [Supported in part by NIH.]The results of Lehiste (1973, 1977) and of Donoran and Darwin (1979) suggest that English speech rhythm is perceived as isochronous, and that this percept is special to speech. Results of two experiments do not support these claims. In both experiments subjects tapped to the beat of LPC resynthesized sentences containing four stressed syllables, or to the beat of analogs of the sentences. In experiment I, which followed the Donovan and Darwin paradigm, the average responses were more nearly even than the interstress intervals of the sentences; on the other hand, more than half of the subjects responded with a rhythm that matched the sentence rhythm more closely than an isochronous one. In experiment II, subjects tapped to one of four versions of the sentence stimuli: (1) LPC resyntbesis; (2) LPC resynthesis with formant bandwidths broadened to 1000 Hz; or sine wave synthesis, either (3) cued as speech or (4) cued as nonspeech. If there is a perceptual effect specific to speech, subjects hearing the speech...

Precise control of the relative phases of two ultrasonic purses using digital logic circuitry

Description is given of a recently constructed device for use in ultrasonic experiments that employ two matched transducers. The device produces two sinusoidal bursts of substantially identical waveform, but with an adjustable delay between their starting times. The bursts are derived digitally from an external frequency standard (crystal clock), with a frequency of 5 MHz; the master frequency for sine wave synthesis can be any integer fraction of this clock frequency. The period of each cycle is ten times the reciprocal of that integer fraction of the master frequency. Any integer number of sinusoidal cycles, from one to nine cycles, are generated as a burst. A delay counter is started coincident with the sinusoidal waveform generator. Upon completion of this preset delay interval a second sine counter is started, which then generates the same number of cycles as there were in the first burst. The delay interval may be adjusted to any integer number of master clock cycles. Thus the two sine wave pulses c...

Accurate sine-function synthesis

A bipolar circuit capable of high-accuracy sinewave synthesis over two quadrants is described. An optimum set of design criteria is established, based on minimising total harmonic distortion.