Discrimination of Schroeder-Phase Harmonic Complexes by Normal-Hearing and Cochlear-Implant Listeners

Drennan, Ward R.; Longnion, Jeff; Ruffin, Chad; Rubinstein, Jay T.

doi:10.1007/s10162-007-0107-6

Cited by 37 publications

(83 citation statements)

References 44 publications

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“…A previous study showed that NH listeners can discriminate between +SCHR and −SCHR with F0s up to 300 to 400 Hz (Dooling et al 2002). Cochlear-implant users can discriminate the +SCHR and -SCHR at better than chance performance for F0s of 400 Hz and less, but they did not perform as well as NH subjects (Drennan et al, 2008). Discrimination of +SCHR and −SCHR has not been tested in HI non-cochlear implant listeners; however, HI canaries have been shown to perform slightly better than NH canaries when discriminating between +SCHR and −SCHR (Lauer et al 2007).…”

Section: Introductionmentioning

confidence: 93%

Discrimination of Time-Reversed Harmonic Complexes by Normal-Hearing and Hearing-Impaired Listeners

Lauer

Molis²,

Leek³

2009

JARO

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Normal-hearing (NH) listeners and hearing-impaired (HI) listeners detected and discriminated timereversed harmonic complexes constructed of equalamplitude harmonic components with fundamental frequencies (F0s) ranging from 50 to 800 Hz. Component starting phases were selected according to the positive and negative Schroeder-phase algorithms to produce within-period frequency sweeps with relatively flat temporal envelopes. Detection thresholds were not affected by component starting phases for either group of listeners. At presentation levels of 80 dB SPL, NH listeners could discriminate the two waveforms nearly perfectly when the F0s were less than 300-400 Hz but fell to chance performance for higher F0s. HI listeners performed significantly poorer, with reduced discrimination at several of the F0s. In contrast, at a lower presentation level meant to nearly equate sensation levels for the two groups, NH listeners' discrimination was poorer than HI listeners at most F0s. Roving presentation levels had little effect on performance by NH listeners but reduced performance by HI listeners. The differential impact of roving level suggests a weaker perception of timbre differences and a greater susceptibility to the detrimental effects of experimental uncertainty in HI listeners.

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Section: Introductionmentioning

confidence: 93%

Discrimination of Time-Reversed Harmonic Complexes by Normal-Hearing and Hearing-Impaired Listeners

Lauer

Molis²,

Leek³

2009

JARO

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“…In addition to developing alternative approaches for representing the information, as mentioned above, future efforts also might be productively directed at developing direct measures of the transmission of fine structure information to implant patients. One promising approach for this has been described quite recently by Drennan et al (2008) and involves discrimination of Schroeder-phase harmonic complexes, which differ in temporal fine structure only. Additional measures may be needed for assessing the transmission of fine structure information for bandpass channels with relatively high center frequencies, e.g., above 400 Hz.…”

Section: Possible Deficit In the Representation Of Fine Structure Infmentioning

confidence: 99%

Cochlear implants: A remarkable past and a brilliant future

2008

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The aims of this paper are to (i) provide a brief history of cochlear implants; (ii) present a status report on the current state of implant engineering and the levels of speech understanding enabled by that engineering; (iii) describe limitations of current signal processing strategies and (iv) suggest new directions for research. With current technology the "average" implant patient, when listening to predictable conversations in quiet, is able to communicate with relative ease. However, in an environment typical of a workplace the average patient has a great deal of difficulty. Patients who are "above average" in terms of speech understanding, can achieve 100% correct scores on the most difficult tests of speech understanding in quiet but also have significant difficulty when signals are presented in noise. The major factors in these outcomes appear to be (i) a loss of low-frequency, fine structure information possibly due to the envelope extraction algorithms common to cochlear implant signal processing; (ii) a limitation in the number of effective channels of stimulation due to overlap in electric fields from electrodes, and (iii) central processing deficits, especially for patients with poor speech understanding. Two recent developments, bilateral implants and combined electric and acoustic stimulation, have promise to remediate some of the difficulties experienced by patients in noise and to reinstate low-frequency fine structure information. If other possibilities are realized, e.g., electrodes that emit drugs to inhibit cell death following trauma and to induce the growth of neurites toward electrodes, then the future is very bright indeed.

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“…As indicated in the BIntroduction^sec-tion, Schroeder-phase discrimination involves both spectral and temporal modulations. Drennan et al (2008) demonstrated that Schroeder-phase discrimination evaluates the ability of CI subjects to differentiate a rising frequency modulation from a falling frequency modulation. Figure 12 shows the electrode Table 8 Same as outputs in response to the 50-Hz negative Schroederphase discrimination stimuli for different experimental sound processors.…”

Section: Discussionmentioning

confidence: 99%

“…The Schroeder-phase discrimination test was implemented using the same method as that previously described by Drennan et al (2008). Positive and negative Schroeder-phase stimulus pairs were created for two different fundamental frequencies (F0s) of 50 and 200 Hz.…”

Section: Testing Proceduresmentioning

confidence: 99%

Spectral and Temporal Analysis of Simulated Dead Regions in Cochlear Implants

Won

Jones

Moon

et al. 2015

JARO

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A cochlear implant (CI) electrode in a Bcochlear dead region^will excite neighboring neural populations. In previous research that simulated such dead regions, stimulus information in the simulated dead region was either added to the immediately adjacent frequency regions or dropped entirely. There was little difference in speech perception ability between the two conditions. This may imply that there may be little benefit of ensuring that stimulus information on an electrode in a suspected cochlear dead region is transmitted. Alternatively, performance may be enhanced by a broader frequency redistribution, rather than adding stimuli from the dead region to the edges. In the current experiments, cochlear dead regions were introduced by excluding selected CI electrodes or vocoder noise-bands. Participants were assessed for speech understanding as well as spectral and temporal sensitivities as a function of the size of simulated dead regions. In one set of tests, the normal input frequency range of the sound processor was distributed among the active electrodes in bands with approximately logarithmic spacing (Bredistributedm aps); in the remaining tests, information in simulated dead regions was dropped (Bdropped^maps). Word recognition and Schroeder-phase discrimination performance, which require both spectral and temporal sensitivities, decreased as the size of simulated dead regions increased, but the redistributed and dropped remappings showed similar performance in these two tasks. Psychoacoustic experiments showed that the near match in word scores may reflect a tradeoff between spectral and temporal sensitivity: spectral-ripple discrimination was substantially degraded in the redistributed condition relative to the dropped condition while performance in a temporal modulation detection task degraded in the dropped condition but remained constant in the redistributed condition.

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Discrimination of Schroeder-Phase Harmonic Complexes by Normal-Hearing and Cochlear-Implant Listeners

Cited by 37 publications

References 44 publications

Discrimination of Time-Reversed Harmonic Complexes by Normal-Hearing and Hearing-Impaired Listeners

Discrimination of Time-Reversed Harmonic Complexes by Normal-Hearing and Hearing-Impaired Listeners

Cochlear implants: A remarkable past and a brilliant future

Spectral and Temporal Analysis of Simulated Dead Regions in Cochlear Implants

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