Features of stimulation affecting tonal-speech perception: implications for cochlear prostheses.
ABSTRACT Tone languages differ from English in that the pitch pattern of a single-syllable word conveys lexical meaning. In the present study, dependence of tonal-speech perception on features of the stimulation was examined using an acoustic simulation of a CIS-type speech-processing strategy for cochlear prostheses. Contributions of spectral features of the speech signals were assessed by varying the number of filter bands, while contributions of temporal envelope features were assessed by varying the low-pass cutoff frequency used for extracting the amplitude envelopes. Ten normal-hearing native Mandarin Chinese speakers were tested. When the low-pass cutoff frequency was fixed at 512 Hz, consonant, vowel, and sentence recognition improved as a function of the number of channels and reached plateau at 4 to 6 channels. Subjective judgments of sound quality continued to improve as the number of channels increased to 12, the highest number tested. Tone recognition, i.e., recognition of the four Mandarin tone patterns, depended on both the number of channels and the low-pass cutoff frequency. The trade-off between the temporal and spectral cues for tone recognition indicates that temporal cues can compensate for diminished spectral cues for tone recognition and vice versa. An additional tone recognition experiment using syllables of equal duration showed a marked decrease in performance, indicating that duration cues contribute to tone recognition. A third experiment showed that recognition of processed FM patterns that mimic Mandarin tone patterns was poor when temporal envelope and duration cues were removed.
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ABSTRACT: Laparoscopic fenestration for treatment of the non-parasitic cyst of the liver has been rarely reported, but sporadic cases appeared elsewhere in the literature. Here we report four cases with symptomatic giant nonparasitic liver cysts which were treated by a laparoscopic fenestration procedure that allowed the successful removal of the cyst dome. Before starting to excise the wall of the cyst, laparoscopic-quided needle aspiration of the cyst fluid was done first in order to clean the visual field for laparoscopic intervention where possible. The cyst wall was usually slightly transparent and somewhat smooth in the external and internal surface of the cysts. It was necessary to lysis the omental adhesion sometime before starting to remove the dome of the cyst. The cyst wall of the exposed part could be removed first with heat-probe instrument through laparoscopy. Those patients were discharged and revealed an uneventful post-operative course in three cases but in one case we had to convert to the traditional laparostomy to perform resection of the multiple cystic lesions. Post-operative echographic study showed that the giant cyst had collapsed. Therefore, we believe laparoscopic fenestration for the liver cyst is simple and effective, if the patient is a candidate who requires operation to remove the dome of the giant cyst.The Kaohsiung journal of medical sciences 10/1997; 13(9):572-7. · 0.61 Impact Factor