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Effects of Adaptation Rate and Noise Suppression on the Intelligibility of Compressed-Envelope Based Speech.

Lai YH, Tsao Y, Chen F - PLoS ONE (2015)

Bottom Line: Experimental results demonstrated that the adaptation rate in envelope compression had a notable effect on the speech intelligibility performance of the AEC strategy.By specifying a suitable adaptation rate, speech intelligibility could be enhanced significantly in noise compared to when using static envelope compression.Moreover, results confirmed that the AEC strategy was suitable for combining with noise reduction to improve the intelligibility of envelope-based speech in noise.

View Article: PubMed Central - PubMed

Affiliation: Research Center for Information Technology Innovation, Academia Sinica, Taipei, Taiwan.

ABSTRACT
Temporal envelope is the primary acoustic cue used in most cochlear implant (CI) speech processors to elicit speech perception for patients fitted with CI devices. Envelope compression narrows down envelope dynamic range and accordingly degrades speech understanding abilities of CI users, especially under challenging listening conditions (e.g., in noise). A new adaptive envelope compression (AEC) strategy was proposed recently, which in contrast to the traditional static envelope compression, is effective at enhancing the modulation depth of envelope waveform by making best use of its dynamic range and thus improving the intelligibility of envelope-based speech. The present study further explored the effect of adaptation rate in envelope compression on the intelligibility of compressed-envelope based speech. Moreover, since noise reduction is another essential unit in modern CI systems, the compatibility of AEC and noise reduction was also investigated. In this study, listening experiments were carried out by presenting vocoded sentences to normal hearing listeners for recognition. Experimental results demonstrated that the adaptation rate in envelope compression had a notable effect on the speech intelligibility performance of the AEC strategy. By specifying a suitable adaptation rate, speech intelligibility could be enhanced significantly in noise compared to when using static envelope compression. Moreover, results confirmed that the AEC strategy was suitable for combining with noise reduction to improve the intelligibility of envelope-based speech in noise.

No MeSH data available.


Related in: MedlinePlus

Examples of amplitude envelope for (a) Wiener+SEC, (b) Wiener+AEC, (d) KLT+SEC, and (e) KLT+AEC processing.The envelope was extracted from the 6th channel of a testing sentence masked by SSN masker at SNR 5 dB, and compressed to 5 dB DR. In (c) and (f), the solid lines show the SF used in the AEC strategy [for (b) and (e)]; the dashed lines show the fixed SF in the SEC strategy [for (a) and (d)].
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pone.0133519.g005: Examples of amplitude envelope for (a) Wiener+SEC, (b) Wiener+AEC, (d) KLT+SEC, and (e) KLT+AEC processing.The envelope was extracted from the 6th channel of a testing sentence masked by SSN masker at SNR 5 dB, and compressed to 5 dB DR. In (c) and (f), the solid lines show the SF used in the AEC strategy [for (b) and (e)]; the dashed lines show the fixed SF in the SEC strategy [for (a) and (d)].

Mentions: Fig 5 shows examples of the amplitude envelope processed by two NR algorithms (i.e., Wiener filtering and KLT) followed by the corresponding SEC and AEC strategies in the same test conditions. The envelope was extracted from the sixth channel, and compressed to 5 dB DR, where the initial SF was computed by the CRE stage. We note two findings: (1) the KLT performance is similar to that of the Wiener filter integrated with the same compression strategy, and (2) AEC can provide better modulation depth than SEC when it is integrated with the same NR algorithm.


Effects of Adaptation Rate and Noise Suppression on the Intelligibility of Compressed-Envelope Based Speech.

Lai YH, Tsao Y, Chen F - PLoS ONE (2015)

Examples of amplitude envelope for (a) Wiener+SEC, (b) Wiener+AEC, (d) KLT+SEC, and (e) KLT+AEC processing.The envelope was extracted from the 6th channel of a testing sentence masked by SSN masker at SNR 5 dB, and compressed to 5 dB DR. In (c) and (f), the solid lines show the SF used in the AEC strategy [for (b) and (e)]; the dashed lines show the fixed SF in the SEC strategy [for (a) and (d)].
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4510405&req=5

pone.0133519.g005: Examples of amplitude envelope for (a) Wiener+SEC, (b) Wiener+AEC, (d) KLT+SEC, and (e) KLT+AEC processing.The envelope was extracted from the 6th channel of a testing sentence masked by SSN masker at SNR 5 dB, and compressed to 5 dB DR. In (c) and (f), the solid lines show the SF used in the AEC strategy [for (b) and (e)]; the dashed lines show the fixed SF in the SEC strategy [for (a) and (d)].
Mentions: Fig 5 shows examples of the amplitude envelope processed by two NR algorithms (i.e., Wiener filtering and KLT) followed by the corresponding SEC and AEC strategies in the same test conditions. The envelope was extracted from the sixth channel, and compressed to 5 dB DR, where the initial SF was computed by the CRE stage. We note two findings: (1) the KLT performance is similar to that of the Wiener filter integrated with the same compression strategy, and (2) AEC can provide better modulation depth than SEC when it is integrated with the same NR algorithm.

Bottom Line: Experimental results demonstrated that the adaptation rate in envelope compression had a notable effect on the speech intelligibility performance of the AEC strategy.By specifying a suitable adaptation rate, speech intelligibility could be enhanced significantly in noise compared to when using static envelope compression.Moreover, results confirmed that the AEC strategy was suitable for combining with noise reduction to improve the intelligibility of envelope-based speech in noise.

View Article: PubMed Central - PubMed

Affiliation: Research Center for Information Technology Innovation, Academia Sinica, Taipei, Taiwan.

ABSTRACT
Temporal envelope is the primary acoustic cue used in most cochlear implant (CI) speech processors to elicit speech perception for patients fitted with CI devices. Envelope compression narrows down envelope dynamic range and accordingly degrades speech understanding abilities of CI users, especially under challenging listening conditions (e.g., in noise). A new adaptive envelope compression (AEC) strategy was proposed recently, which in contrast to the traditional static envelope compression, is effective at enhancing the modulation depth of envelope waveform by making best use of its dynamic range and thus improving the intelligibility of envelope-based speech. The present study further explored the effect of adaptation rate in envelope compression on the intelligibility of compressed-envelope based speech. Moreover, since noise reduction is another essential unit in modern CI systems, the compatibility of AEC and noise reduction was also investigated. In this study, listening experiments were carried out by presenting vocoded sentences to normal hearing listeners for recognition. Experimental results demonstrated that the adaptation rate in envelope compression had a notable effect on the speech intelligibility performance of the AEC strategy. By specifying a suitable adaptation rate, speech intelligibility could be enhanced significantly in noise compared to when using static envelope compression. Moreover, results confirmed that the AEC strategy was suitable for combining with noise reduction to improve the intelligibility of envelope-based speech in noise.

No MeSH data available.


Related in: MedlinePlus