Objective and subjective optimization of APC system performance

Gibson, J.D.; Chang, Wen‐Whei

doi:10.1109/29.56067

Cited by 2 publications

(3 citation statements)

References 8 publications

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“…We found in some previous work on forward adaptive APC that the structure in Fig. 3 gave the best results [53] by a slight margin. This ordering also seems preferable for backward adaptation, since the algorithm…”

Section: Tree Codersmentioning

confidence: 72%

“…However, the subjective quality and intelligibility at 9.6 kb/s is quite good with an extremely low level of granular noise. In comparison to 9.6 kb/s APC systems that we have studied extensively [53], the 9.6 kb/s multitree coder exhibits none of the spectral distortions of heavily center clipped APC systems and far less granular noise than SNRSEG optimized APC systems. We have not conducted performance comparisons with multipulse LPC and CELP at 9.6 kb/s.…”

Section: Performance Comparisonsmentioning

confidence: 91%

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Fractional rate multitree speech coding

Gibson

Chang

1991

IEEE Trans. Commun.

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We present both forward and backward adaptive speech coders that operate at 9.6, 12, and 16 kb/s using integer and fractional rate trees, weighted squared error distortion measures, the (M,L) tree search algorithm, and incremental path map symbol release. We introduce the concept of multitree source codes and illustrate how the multitree structure allows scalar quantizer-based codes and scalar adaptation rules to be used for fractional rate tree coding. With a frequency weighted distortion measure, the forward and backward adaptive multitree coders produce near toll quality speech at 16 kb/s, while the backward adaptive 9.6 kb/s multitree coder substantially outperforms adaptive predictive coding and has an encoding delay less than 2 ms. Performance results are presented in terms of Unweighted and weighted signal-to-noise ratio and segmental signal-to-noise ratio, sound spectrograms, and subjective listening tests.

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Section: Tree Codersmentioning

confidence: 72%

Section: Performance Comparisonsmentioning

confidence: 91%

Fractional rate multitree speech coding

Gibson

Chang

1991

IEEE Trans. Commun.

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“…Unfortunately, as shown in Part II of this paper [3] and in [4]- [6], when they are used to evaluate more general coding and transmission systems, SNR and SNRseg often show little, if any, correlation to perceived speech quality. The continued popularity of these two estimators is likely due to their history, their simplicity, and the lack of a widely tested and accepted replacement.…”

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confidence: 99%

Objective estimation of perceived speech quality. I. Development of the measuring normalizing block technique

Voran

1999

IEEE Trans. Speech Audio Process.

103

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Perceived speech quality is most directly measured by subjective listening tests. These tests are often slow and expensive, and numerous attempts have been made to supplement them with objective estimators of perceived speech quality. These attempts have found limited success, primarily in analog and higher-rate, error-free digital environments where speech waveforms are preserved or nearly preserved. The objective estimation of the perceived quality of highly compressed digital speech, possibly with bit errors or frame erasures has remained an open question. We report our findings regarding two essential components of objective estimators of perceived speech quality: perceptual transformations and distance measures. A perceptual transformation modifies a representation of an audio signal in a way that is approximately equivalent to the human hearing process. A distance measure reflects the magnitude of a perceived distance between two perceptually transformed signals.We then describe a new objective estimation approach that uses a simple but effective perceptual transformation and a distance measure that consists of a hierarchy of measuring normalizing blocks. Each measuring normalizing block integrates two perceptually transformed signals over some time or frequency interval to determine the average difference across that interval. This difference is then normalized out of one signal, and is further processed to generate one or more measurements. The resulting new estimators, and several established estimators, are thoroughly evaluated and compared in Part II of this paper. Hierarchical structures of measuring normalizing blocks, or other structures of measuring normalizing blocks may also address open issues in perceived audio quality estimation, layered speech or audio coding, automatic speech or speaker recognition, audio signal enhancement, and other areas.

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Objective and subjective optimization of APC system performance

Cited by 2 publications

References 8 publications

Fractional rate multitree speech coding

Fractional rate multitree speech coding

Objective estimation of perceived speech quality. I. Development of the measuring normalizing block technique

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