Journal of the Audio Engineering Society

2010 June - Volume 58 Number 6


Theory and Practice of Modified Frequency Modulation Synthesis

Authors: Lazzarini, Victor; Timoney, Joseph

Frequency modulation synthesis of musical instruments has been studied for years and its limitations are well known. By modifying the basic closed-form equations to work in the complex domain, an alternative method that can overcome some of these limitations is presented. The proposed approach provides a smoothly evolving spectrum with regard to variations in modulation index. A phase-synchronous version is discussed with application to resonant and formant synthesis. A comparison with the classical frequency modulation approach illustrates its advantages. Adaptive applications of the algorithm are introduced and explored.

Frequency Dependence of Damping and Compliance in Loudspeaker Suspensions

Authors: Thorborg, Knud; Tinggaard, Carsten; Agerkvist, Finn; Futtrup, Claus

Commonly used materials for loudspeaker suspensions have been shown to have viscoelastic properties, best known is the “creep” effect. This phenomenon, while known, is normally of little interest because it is primarily a dc issue outside of the audio frequency range. However, this viscoelasticity phenomenon also has a frequency-dependent influence on damping and compliance. Because damping is inversely proportional to frequency, a simplified model only including frequency-dependent damping is presented. The model provides an acceptable fit for empirical data.

Engineering reports

In order to determine the acceptable compression rate for MP3 codecs, listeners were asked to discriminate various rates for eight different musical instruments. The clarinet proved to be most sensitive to compression even at rates approaching 128 kbps, while the horn was least sensitive at rates of 56 kbps. Discrimination scores were strongly correlated with the signal-to-mask ratio and spectral irregularity. Spectral error accounted for more than 80% of the discrimination variance. Objective measures of the sound source predict most of the discrimination sensitivity.

Synthesis of the Dan Trahn Based on a Parameter Extraction System

Authors: Cho, Sang-Jin; Chong, Ul-Pil; Cho, Sang-Bock

The authors present a model for synthesizing the sound of the Vietnamese plucked string instrument called the dan tranh. The model’s parameters are estimated from the short-time Fourier transform, and the synthesized sound is generated using a single delay loop. The excitation, which is determined by the body structure of the instrument, plays an important role in achieving a natural sound. The results are compared to both the Korean gayageum with silk strings and the acoustic guitar with steel strings.

Standards and Information Documents

AES Standards Committee News


Wireless Microphones for Live Sound

Authors: Rumsey, Francis

[Feature] Significant changes in regulation have affected the operation of wireless microphones in recent years. During two live sound seminars held at the 127th Convention in New York last year, experts in the field reviewed the current state of play, particularly considering the increased competition for spectrum "real estate" in the UHF band. Ways of making the best use of wireless microphone technology in practical applications were proposed, including antenna arrangements and frequency planning.

41st Conference, London, Call for Papers


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