Relative contributions of passband and filter skirts to the intelligibility of bandpass speech: Some effects of context and amplitude

Bashford, James A.; Warren, Richard M.; Lenz, Peter

doi:10.1121/1.1329836

Cited by 11 publications

(3 citation statements)

References 7 publications

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“…This was found for filtered speech in quiet and when presented in broadband or notch-filtered noise (i.e., noise filling the spectral gaps of missing speech). These results are consistent with a long lineage of studies by Warren and colleagues demonstrating a super-additivity of sparsely represented speech (e.g., Warren et al, 1995;Warren et al, 1997;Warren and Bashford, 1999;Healy and Warren, 2003;Warren et al, 2005;Bashford et al, 2000). That is, significant speech recognition can be obtained with narrow speech bands if they sufficiently sample the frequency spectrum.…”

Section: Discussionsupporting

confidence: 90%

Glimpsing speech in temporally and spectro-temporally modulated noise

Fogerty

Carter

Healy

2018

The Journal of the Acoustical Society of America

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Speech recognition in fluctuating maskers is influenced by the spectro-temporal properties of the noise. Three experiments examined different temporal and spectro-temporal noise properties. Experiment 1 replicated previous work by highlighting maximum performance at a temporal gating rate of 4-8 Hz. Experiment 2 involved spectro-temporal glimpses. Performance was best with the largest glimpses, and performance with small glimpses approached that for continuous noise matched to the average level of the modulated noise. Better performance occurred with periodic than for random spectro-temporal glimpses. Finally, time and frequency for spectro-temporal glimpses were dissociated in experiment 3. Larger spectral glimpses were more beneficial than smaller, and minimum performance was observed at a gating rate of 4-8 Hz. The current results involving continuous speech in gated noise (slower and larger glimpses most advantageous) run counter to several results involving gated and/or filtered speech, where a larger number of smaller speech samples is often advantageous. This is because mechanisms of masking dominate, negating the advantages of better speech-information sampling. It is suggested that spectro-temporal glimpsing combines temporal glimpsing with additional processes of simultaneous masking and uncomodulation, and continuous speech in gated noise is a better model for real-world glimpsing than is gated and/or filtered speech.

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Section: Discussionsupporting

confidence: 90%

Glimpsing speech in temporally and spectro-temporally modulated noise

Fogerty

Carter

Healy

2018

The Journal of the Acoustical Society of America

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“…Another study also employed the 1 / 3-octave everyday sentences centered at 1.5 kHz with transition bands of 100 dBA/octave, and truncated the filter skirts at a series of increasing distances from the cutoff frequency using 2000-order FIR filtering. It was found that statistically significant contributions from these transition bands could be made for frequencies attenuated by 30 dBA, so that the nominal 1 / 3-octave band had a much larger effective bandwidth ͑i.e., the range of frequencies contributing to intelligibility͒ that extended to almost one octave ͑Warren, Bashford, and Lenz, 2000͒. While these experiments using 2000-order FIR filtering demonstrated the major role played by transition bands in determining intelligibilities of filtered speech, none of these experiments employed filter slopes steep enough to remove all contributions from transition bands, and so permit measurement of passband intelligibilities.…”

Section: Introductionmentioning

confidence: 98%

Intelligibilities of 1-octave rectangular bands spanning the speech spectrum when heard separately and paired

Warren

Bashford

Lenz

2005

The Journal of the Acoustical Society of America

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There is a need, both for speech theory and for many practical applications, to know the intelligibilities of individual passbands that span the speech spectrum when they are heard singly and in combination. While indirect procedures have been employed for estimating passband intelligibilities (e.g., the Speech Intelligibility Index), direct measurements have been blocked by the confounding contributions from transition band slopes that accompany filtering. A recent study has reported that slopes of several thousand dBA/octave produced by high-order finite impulse response filtering were required to produce the effectively rectangular bands necessary to eliminate appreciable contributions from transition bands [Warren et al., J. Acoust. Soc. Am. 115, 1292-1295 (2004)]. Using such essentially vertical slopes, the present study employed sentences, and reports the intelligibilities of their six 1-octave contiguous passbands having center frequencies from 0.25 to 8 kHz when heard alone, and for each of their 15 possible pairings.

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“…Namely Bashford et al found a score of 26% for the 1/3 octave 96 dB/oct filter. After the electronic filters had been replaced with very high order digital filters, the score dropped to 4% (Bashford et al, 2000).…”

Section: Warrenmentioning

confidence: 99%

Articulation and Intelligibility

Allen¹

2005

Synthesis Lectures on Speech and Audio Processing

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Immediately following the Second World War, between 1947 and 1955, several classic papers quantified the fundamentals of human speech information processing and recognition. In 1947 French and Steinberg published their classic study on the articulation index. In 1948 Claude Shannon published his famous work on the theory of information. In 1950 Fletcher and Galt published their theory of the articulation index, a theory that Fletcher had worked on for 30 years, which integrated his classic works on loudness and speech perception with models of speech intelligibility. In 1951 George Miller then wrote the first book Language and Communication, analyzing human speech communication with Claude Shannon's just published theory of information. Finally in 1955 George Miller published the first extensive analysis of phone decoding, in the form of confusion matrices, as a function of the speech-to-noise ratio. This work extended the Bell Labs' speech articulation studies with ideas from Shannon's Information theory. Both Miller and Fletcher showed that speech, as a code, is incredibly robust to mangling distortions of filtering and noise. Regrettably much of this early work was forgotten. While the key science of information theory blossomed, other than the work of George Miller, it was rarely applied to aural speech research. The robustness of speech, which is the most amazing thing about the speech code, has rarely been studied. It is my belief (i.e., assumption) that we can analyze speech intelligibility with the scientific method. The quantitative analysis of speech intelligibility requires both science and art. The scientific component requires an error analysis of spoken communication, which depends critically on the use of statistics, information theory, and psychophysical methods. The artistic component depends on knowing how to restrict the problem in such a way that progress may be made. It is critical to tease out the relevant from the irrelevant and dig for the key issues. This will focus us on the decoding of nonsense phonemes with no visual component, which have been mangled by filtering and noise. This monograph is a summary and theory of human speech recognition. It builds on and integrates the work of Fletcher, Miller, and Shannon. The long-term goal is to develop a quantitative theory for predicting the recognition of speech sounds. In Chapter 2 the theory is developed for maximum entropy (MaxEnt) speech sounds, also called nonsense speech. In Chapter 3, context is factored in. The book is largely reflective, and quantitative, with a secondary goal of providing an historical context, along with the many deep insights found in these early works.

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Relative contributions of passband and filter skirts to the intelligibility of bandpass speech: Some effects of context and amplitude

Cited by 11 publications

References 7 publications

Glimpsing speech in temporally and spectro-temporally modulated noise

Glimpsing speech in temporally and spectro-temporally modulated noise

Intelligibilities of 1-octave rectangular bands spanning the speech spectrum when heard separately and paired

Articulation and Intelligibility

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