Browsing by Subject "intelligibility"
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Item Effects Of Signal Level And Spectral Contrast On Vowel Formant Discrimination For Normal-Hearing And Hearing-Impaired Listeners(2013-06) Woodall, Ashley; Liu, Chang; Woodall, Ashley; Liu, ChangPurpose: The aim of this study was to determine whether increasing the overall speech level or the individual spectral contrasts of vowel sounds can improve vowel formant discrimination for listeners both with and without normal hearing. Method: Thresholds of vowel formant discrimination were examined for the F2 frequencies of 3 American English vowels for listeners with and without normal hearing. Spectral contrasts of the F2 were enhanced by 3, 6, and 9 dB. Vowel stimuli were presented at 70 and 90 dB SPL. Results: The thresholds of listeners with hearing impairment were reduced significantly after spectral enhancement was implemented, especially at 90 dB SPL, whereas normal-hearing listeners did not benefit from spectral enhancement. Conclusion: These results indicate that a combination of spectral enhancement of F2 and high speech level is most beneficial to improve vowel formant discrimination for listeners with hearing impairment.Item Masking Release And Modulation Interference In Cochlear Implant And Simulation Listeners(2013-06) Jin, Su-Hyun; Nie, Yingjiu; Nelson, Peggy; Jin, Su-HyunPurpose: To examine the effects of temporal and spectral interference of masking noise on sentence recognition for listeners with cochlear implants (CI) and normal-hearing persons listening to vocoded signals that simulate signals processed through a CI (NH-Sim). Method: NH-Sim and CI listeners participated in the experiments using speech and noise that were processed by bandpass filters. Depending on the experimental condition, the spectra of the maskers relative to that of speech were set to be completely embedded with, partially overlapping, or completely separate from, the speech. The maskers were either steady or amplitude modulated and were presented at +10 dB signal-to-noise ratio. Results: NH-Sim listeners experienced progressively more masking as the masker became more spectrally overlapping with speech, whereas CI listeners experienced masking even when the masker was spectrally remote from the speech signal. Both the NH-Sim and CI listeners experienced significant modulation interference when noise was modulated at a syllabic rate (4 Hz), suggesting that listeners may experience both modulation interference and masking release. Thus, modulated noise has mixed and counteracting effects on speech perception. Conclusion: When the NH-Sim and CI listeners with poor spectral resolution were tested using syllabic-like rates of modulated noise, they tended to integrate or confuse the noise with the speech, causing an increase in speech errors. Optional training programs might be useful for CI listeners who show more difficulty understanding speech in noise.Item Speaking style adaptations across the lifespan(2014-04) Ferracane, Elisa; Gilbert, Rachael; Smiljanic, Rajka; Johnson, Karen; Trimble-Quiz, Cristabella; Smiljanic, RajkaIn everyday life, speech communication occurs in suboptimal or adverse conditions (e.g., talking to a listener who is hard of hearing; presence of noise in the environment). This study examines how talkers change the way they speak in response to challenging communicative situations. We investigate what consequences such changes have on intelligibility and whether speaking style adaptations vary with the talker's age.