Analyses of Decimation Filter Stopband Attenuation Influence on Subjective Quality of Audio Signals

Abstract

Decimation is a frequently used technique in audio signal processing. This paper investigates the influence of the values of stopband attenuation of decimation filters on the subjective perception of resulting audio signals. In practice, the demands for stopband attenuation of these filters are quite rigorous. The paper examines how justified these demands are from the psychoacoustic point of view. Basic procedure within such a research is a subjective test. Aside from objective parameters, the subjective evaluation is a method that can give insight into the characteristics of audio signal processing under testing. Results of subjective testing of the influence of different values of stopband attenuation on the perceptibility of interfering signal are presented for various audio signals. Two types of interfering signals were used in the subjective test. To increase the validity of psychoacoustic test, the probability of false detection of differences is measured by presenting subjects with equivalent signals. The results of subjective testing can prove to be useful in the design process of decimation filters for audio system applications.

Keywords

• Subjective testing
• Decimation
• Filters
• Psychoacoustics
• Placebo
• Critical bands