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  • 1
    In: Lung Cancer, Elsevier BV, Vol. 41 ( 2003-8), p. S169-
    Type of Medium: Online Resource
    ISSN: 0169-5002
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2003
    detail.hit.zdb_id: 632771-0
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  • 2
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2001
    In:  The Journal of the Acoustical Society of America Vol. 109, No. 1 ( 2001-01-01), p. 379-384
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 109, No. 1 ( 2001-01-01), p. 379-384
    Abstract: This study evaluated the effects of time compression and expansion on sentence recognition by normal-hearing (NH) listeners and cochlear-implant (CI) recipients of the Nucleus-22 device. Sentence recognition was measured in five CI users using custom 4-channel continuous interleaved sampler (CIS) processors and five NH listeners using either 4-channel or 32-channel noise-band processors. For NH listeners, recognition was largely unaffected by time expansion, regardless of spectral resolution. However, recognition of time-compressed speech varied significantly with spectral resolution. When fine spectral resolution (32 channels) was available, speech recognition was unaffected even when the duration of sentences was shortened to 40% of their original length (equivalent to a mean duration of 40 ms/phoneme). However, a mean duration of 60 ms/phoneme was required to achieve the same level of recognition when only coarse spectral resolution (4 channels) was available. Recognition patterns were highly variable across CI listeners. The best CI listener performed as well as NH subjects listening to corresponding spectral conditions; however, three out of five CI listeners performed significantly poorer in recognizing time-compressed speech. Further investigation revealed that these three poorer-performing CI users also had more difficulty with simple temporal gap-detection tasks. The results indicate that limited spectral resolution reduces the ability to recognize time-compressed speech. Some CI listeners have more difficulty with time-compressed speech, as produced by rapid speakers, because of reduced spectral resolution and deficits in auditory temporal processing.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2001
    detail.hit.zdb_id: 1461063-2
    detail.hit.zdb_id: 219231-7
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  • 3
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2002
    In:  The Journal of the Acoustical Society of America Vol. 111, No. 5_Supplement ( 2002-05-01), p. 2429-2429
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 111, No. 5_Supplement ( 2002-05-01), p. 2429-2429
    Abstract: We used the following method to measure auditory streaming in CI listeners: a ‘‘test’’ pattern is composed of two loudness-matched tones A and B presented in the sequence AABAABAAB... & lt;th & gt;. If A and B are perceptually separable, the subject should hear ‘‘AA...AA...AA...’’ and ‘‘B...B...B...’’ as the two separate streams. The subject hears a ‘‘preview’’ sequence of tones which can have the rhythm of either tone B or tone A in the pattern (e.g., X...X...X...X or XX...XX...XX...), where X is the preview tone. The subject indicates whether or not she/he heard the rhythm of the preview sequence in the test sequence. A number of sets of A, B, and X are set up, and the subject is presented with the different patterns in random order. Results suggest CI listeners are able to perceptually separate tonal sequences into auditory streams. The tonotopic distance (electrode pair separation) between tones is an important factor for streaming. However, listeners are also able to stream sequences of tones presented to the same electrode pair (tonotopic location) but with different temporal envelopes. [Work supported by NIDCD.]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2002
    detail.hit.zdb_id: 1461063-2
    detail.hit.zdb_id: 219231-7
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  • 4
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2002
    In:  JARO - Journal of the Association for Research in Otolaryngology Vol. 3, No. 2 ( 2002-6-1), p. 185-199
    In: JARO - Journal of the Association for Research in Otolaryngology, Springer Science and Business Media LLC, Vol. 3, No. 2 ( 2002-6-1), p. 185-199
    Type of Medium: Online Resource
    ISSN: 1525-3961 , 1438-7573
    Language: Unknown
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2002
    detail.hit.zdb_id: 2025609-7
    detail.hit.zdb_id: 2021417-0
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  • 5
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2002
    In:  The Journal of the Acoustical Society of America Vol. 112, No. 4 ( 2002-10-01), p. 1664-1674
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 112, No. 4 ( 2002-10-01), p. 1664-1674
    Abstract: The goal of the present study was to investigate the time course of adaptation by experienced cochlear implant users to a shifted frequency-to-electrode assignment in their speech processors. Speech recognition performance of three Nucleus-22 cochlear implant users was measured over a 3-month period, during which the implant listeners continuously wore “experimental” speech processors that were purposely shifted by 2–4 mm in terms of the frequency-to-electrode assignment relative to their normal processor. Baseline speech performance was measured with each subject’s clinically assigned speech processor just prior to implementation of the experimental processor. Baseline speech performance was measured again after the 3-month test period, immediately following the reinstallation of the clinically assigned processor settings. Speech performance with the experimental processor was measured four times during the first week, and weekly thereafter over the 3-month period. Results showed that the experimental processor produced significantly lower performance on all measures of speech recognition immediately following implementation. Over the 3-month test period, consonant and HINT sentence recognition with the experimental processors gradually approached a performance level comparable to but still significantly below the baseline and postexperiment measures made with the clinically assigned processor. However, vowel and TIMIT sentence recognition with the experimental processors remained far below the level of the baseline measures even at the end of the 3-month experimental period. There was no significant change in performance with the clinically assigned processor before or after fitting with the experimental processor. The results suggest that a long-time exposure to a new pattern of stimulation may not be able to compensate for the deficit in performance caused by a 2–4-mm shift in the tonotopic location of stimulation, at least within a 3-month period.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2002
    detail.hit.zdb_id: 1461063-2
    detail.hit.zdb_id: 219231-7
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  • 6
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2004
    In:  The Journal of the Acoustical Society of America Vol. 115, No. 4 ( 2004-04-01), p. 1385-1386
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 115, No. 4 ( 2004-04-01), p. 1385-1386
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2004
    detail.hit.zdb_id: 1461063-2
    detail.hit.zdb_id: 219231-7
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  • 7
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2001
    In:  The Journal of the Acoustical Society of America Vol. 109, No. 3 ( 2001-03-01), p. 1166-1172
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 109, No. 3 ( 2001-03-01), p. 1166-1172
    Abstract: This experiment examined the effects of spectral resolution and fine spectral structure on recognition of spectrally asynchronous sentences by normal-hearing and cochlear implant listeners. Sentence recognition was measured in six normal-hearing subjects listening to either full-spectrum or noise-band processors and five Nucleus-22 cochlear implant listeners fitted with 4-channel continuous interleaved sampling (CIS) processors. For the full-spectrum processor, the speech signals were divided into either 4 or 16 channels. For the noise-band processor, after band-pass filtering into 4 or 16 channels, the envelope of each channel was extracted and used to modulate noise of the same bandwidth as the analysis band, thus eliminating the fine spectral structure available in the full-spectrum processor. For the 4-channel CIS processor, the amplitude envelopes extracted from four bands were transformed to electric currents by a power function and the resulting electric currents were used to modulate pulse trains delivered to four electrode pairs. For all processors, the output of each channel was time-shifted relative to other channels, varying the channel delay across channels from 0 to 240 ms (in 40-ms steps). Within each delay condition, all channels were desynchronized such that the cross-channel delays between adjacent channels were maximized, thereby avoiding local pockets of channel synchrony. Results show no significant difference between the 4- and 16-channel full-spectrum speech processor for normal-hearing listeners. Recognition scores dropped significantly only when the maximum delay reached 200 ms for the 4-channel processor and 240 ms for the 16-channel processor. When fine spectral structures were removed in the noise-band processor, sentence recognition dropped significantly when the maximum delay was 160 ms for the 16-channel noise-band processor and 40 ms for the 4-channel noise-band processor. There was no significant difference between implant listeners using the 4-channel CIS processor and normal-hearing listeners using the 4-channel noise-band processor. The results imply that when fine spectral structures are not available, as in the implant listener’s case, increased spectral resolution is important for overcoming cross-channel asynchrony in speech signals.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2001
    detail.hit.zdb_id: 1461063-2
    detail.hit.zdb_id: 219231-7
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  • 8
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2000
    In:  The Journal of the Acoustical Society of America Vol. 108, No. 5_Supplement ( 2000-11-01), p. 2602-2602
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 108, No. 5_Supplement ( 2000-11-01), p. 2602-2602
    Abstract: For cochlear implant (CI) users, the cochlear insertion depth and limited spatial extent of the electrode array causes a mismatch between the frequency content of speech signals and the place of stimulation along the cochlea. To examine the effects of such a spectral mismatch on HINT sentence recognition in noise, five normal-hearing (NH) listeners were tested using noise-band speech processors designed to simulate a variety of cochlear insertion depths. The speech reception threshold (SRT) was measured for two conditions: (1) analysis and carrier bands matched to the insertion depth, and (2) analysis bands fixed over a wide range while carrier bands varied according to insertion depth. In the matched condition, subjects’ performance remained flat along the entire range of insertion depths; on average, the SRT was 5 dB lower than the mismatched condition, indicating that a frequency-limited, but spectrally matched processor provided more benefit. In the mismatched condition, performance was flat over most of the range of insertion depths and declined only for extremely basal or apical insertions. The results indicate that electrode insertion depth and the resulting spectral mismatch is probably not the limiting factor affecting speech recognition or contributing to the variability in performance observed among CI users.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2000
    detail.hit.zdb_id: 1461063-2
    detail.hit.zdb_id: 219231-7
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  • 9
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2003
    In:  The Journal of the Acoustical Society of America Vol. 113, No. 2 ( 2003-02-01), p. 1065-1072
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 113, No. 2 ( 2003-02-01), p. 1065-1072
    Abstract: The present study examined the effects of short-term perceptual training on normal-hearing listeners’ ability to adapt to spectrally altered speech patterns. Using noise-band vocoder processing, acoustic information was spectrally distorted by shifting speech information from one frequency region to another. Six subjects were tested with spectrally shifted sentences after five days of practice with upwardly shifted training sentences. Training with upwardly shifted sentences significantly improved recognition of upwardly shifted speech; recognition of downwardly shifted speech was nearly unchanged. Three subjects were later trained with downwardly shifted speech. Results showed that the mean improvement was comparable to that observed with the upwardly shifted training. In this retrain and retest condition, performance was largely unchanged for upwardly shifted sentence recognition, suggesting that these listeners had retained some of the improved speech perception resulting from the previous training. The results suggest that listeners are able to partially adapt to a spectral shift in acoustic speech patterns over the short-term, given sufficient training. However, the improvement was localized to where the spectral shift was trained, as no change in performance was observed for spectrally altered speech outside of the trained regions.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2003
    detail.hit.zdb_id: 1461063-2
    detail.hit.zdb_id: 219231-7
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  • 10
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2004
    In:  The Journal of the Acoustical Society of America Vol. 115, No. 5_Supplement ( 2004-05-01), p. 2385-2385
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 115, No. 5_Supplement ( 2004-05-01), p. 2385-2385
    Abstract: In cochlear implants (CIs), an electrode’s pitch is largely determined by the excitation pattern produced by stimulation. For CI users, is pitch perception most strongly influenced by the peak, edge or some intermediate location within the excitation pattern? By varying the stimulation mode at four evenly spaced electrode locations, four spectral profiles were hypothesized: single-peaked, apically weighted, basally weighted or multi-peaked (with an intermediate pitch). Forward-masked excitation patterns and pitch judgments were obtained for the four electrode locations, for all experimental stimulation modes, relative to a standard set of BP1 electrodes. Results showed individual differences in CI users’ excitation patterns and pitch judgments produced by the different stimulation modes. Most subjects’ pitch judgments were sensitive to single, sharp peaks in the excitation pattern; however, subjects differed in their sensitivity to broader, multi-peaked patterns. For widely spaced electrode configurations, some subjects consistently judged pitch according to the apical edge of stimulation, some to the basal edge and others to an intermediate location. For some electrode locations, varying the stimulation mode produced significantly different pitches and excitation patterns. Future speech processing strategies may wish to combine stimulation modes to improve the spectral resolution available with a fixed number of implanted electrodes.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2004
    detail.hit.zdb_id: 1461063-2
    detail.hit.zdb_id: 219231-7
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