Comodulation masking release in bit-rate reduction systems

Martin D. Vestergaard, Karsten Bo Rasmussen, Torben Poulsen

    Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review


    It has been suggested that the level dependence of the upper masking slopebe utilised in perceptual models in bit-rate reduction systems. However,comodulation masking release (CMR) phenomena lead to a reduction of themasking effect when a masker and a probe signal are amplitude modulated withthe same frequency. In bit-rate reduction systems the masker would be theaudio signal and the probe signal would represent the quantization noise.Masking curves have been determined for sinusoids and 1-Bark-wide noisemaskers in order to investigate the risk of CMR, when quantizing depths arefixed in accordance with psycho-acoustical principles. Masker frequencies of500Hz, 1kHz and 2kHz have been investigated, and the masking of pure toneprobes has been determined in the first four 1/3 octaves above the masker.Modulation frequencies between 6Hz and 20Hz were used with a modulationdepth of 0.75. CMR of up to 10dB was obtained at a distance of 6 Bark abovethe masker. The amount of CMR was found to depend on the presentation levelof the masker; a higher masker level leads to a higher CMR-effect. Hence,the risk of CMR affecting the subjective performance of bit-rate reductionsystems cannot be ruled out.

    Original languageEnglish
    Title of host publicationActa Acustica Supplement 1 : Collected Papers
    Number of pages4
    PublisherS. Hirzel
    Publication date1999
    Publication statusPublished - 1999
    Event137th Regular Meeting of the Acoustical Society of America, 2nd Convention of the European Acoustics Association - Technical University of Berlin, Berlin, Germany
    Duration: 15 Mar 199919 Mar 1999


    Conference137th Regular Meeting of the Acoustical Society of America, 2nd Convention of the European Acoustics Association
    LocationTechnical University of Berlin


    Dive into the research topics of 'Comodulation masking release in bit-rate reduction systems'. Together they form a unique fingerprint.

    Cite this