Erwin Szopos

Comparative Performance Analysis of Artificial Reverberation Algorithms

The paper considers two efficient improved artificial reverberation algorithms built with an early Schroeders and a late reverberator: modified Schroeders or an absorbent all-pass. Both of them simulate the behavior of a real concert hall by taking into account the variation with frequency of the reverberation time. Several reverberation algorithms can be found in the literature, but very few design and performance analysis hints are given. Our paper includes a detailed design of the reverberators, simulations are run for each algorithm, acoustic parameters are computed and an objective performance analysis is carried out

Aspects of reverberation algorithms

Artificial reverberation is used in different domains from cinematography to psychology for enhancement of rooms acoustical properties. Reverberation is a phenomenon with benefit effect in music. The paper starts with the presentation of the reverberation phenomenon followed by a description of some early and late reverberation algorithms. Then we show the structure of two complete reverberators: classical and improved ones. The advantages of the latter with respect to the impulse response and natural sounding are pointed out.

On improved reverberation algorithms

Artlfcial reverberation is wed in different domains fiom CinematoRaphy to psychology. Important applications are production of special efsects, enhancement of room S momtical properties or improvement of hearing problems. l3e paper starts with the presentation of some clarsical reverberation algorithms, where neither frequency dependence for the reverberation time nor a precise rules for design can be set iip. The traditional reverberators were improved by intrdirction of absorptive j?liers. The paper provides their detailed and simulations to prove their good performance.

Four quadrant log-domain analog current multiplier

In this paper we propose a log-domain four quadrant current multiplier. This circuit can be used in modular log- domain VLSI architectures. The simplicity, low power consumption and high frequency operation recommend it for real time applications.

Discrete domain modeling of an all-digital frequency locked loop

In this paper an all-digital frequency locked loop — which is composed of a digitally controlled oscillator, a counter and a latch (with the scope of frequency detection) and an accumulator in the control loop — is modeled in the z-domain considering two significant error sources that occur in its structure: the finite resolution of the digital signals and the inaccuracy of the frequency detection. The developed discrete time model was implemented in LabVIEW and it was compared against a structural description of the frequency locked loop achieved in Verilog. Simulation results for digitally controlled oscillator with 8, 10 and 12 bits resolution were obtained for both models. Employing a low resolution digitally controlled oscillator the loop can achieve frequency lock in less time, but its jitter performance is worst. The jitter can be improved if higher resolution is used, at the cost of a higher frequency lock time. The peak-to-peak jitter performance was plotted against the resolution of the digitally controlled oscillator that is helpful to determine the minimum for a desiredjitter.

System identification with adaptive algorithms

The paper presents the adaptive LMS algorithm used for system identification. The unknown system is modeled by a FIR filter. After the presentation of the theoretical approach, simulations in Labview and Matlab are provided showing the performance of the method.