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71.
Cochlear implants provide users with limited spectral and temporal information. In this study, the amount of spectral and temporal information was systematically varied through simulations of cochlear implant processors using a noise-excited vocoder. Spectral information was controlled by varying the number of channels between 1 and 16, and temporal information was controlled by varying the lowpass cutoff frequencies of the envelope extractors from 1 to 512 Hz. Consonants and vowels processed using those conditions were presented to seven normal-hearing native-English-speaking listeners for identification. The results demonstrated that both spectral and temporal cues were important for consonant and vowel recognition with the spectral cues having a greater effect than the temporal cues for the ranges of numbers of channels and lowpass cutoff frequencies tested. The lowpass cutoff for asymptotic performance in consonant and vowel recognition was 16 and 4 Hz, respectively. The number of channels at which performance plateaued for consonants and vowels was 8 and 12, respectively. Within the above-mentioned ranges of lowpass cutoff frequency and number of channels, the temporal and spectral cues showed a tradeoff for phoneme recognition. Information transfer analyses showed different relative contributions of spectral and temporal cues in the perception of various phonetic/acoustic features. 相似文献
72.
Rigby JH Laxmisha MS Hudson AR Heap CH Heeg MJ 《The Journal of organic chemistry》2004,69(20):6751-6760
An efficient protecting group controlled regioselective chromium(0)-mediated three-component higher order cycloaddition of tethered diynes with cyclic trienes that generates five rings and six stereogenic centers in one step is described. Following a sequence of reactions featuring a chemoselective Baeyer-Villiger rearrangement and a regioselective cyclopropane hydrogenolysis, the total synthesis of 9-epi-pentalenic acid was achieved. 相似文献
73.
Scanning probe lithography (SPL) is applied to pattern fluid lipid membranes on a solid borosilicate substrate. Grids of metal lines, prepatterned onto the substrate by electron beam lithography, serve to partition the supported membrane into an array of isolated fluid pixels. By toggling the pH of the surrounding solution, the effect of the probe tip on the membrane can be regulated. Alkaline conditions favor membrane removal, while neutral pH favors membrane deposition. Arbitrary membrane patterns with spatial dimensions limited by the underlying grid size can be constructed by sequential SPL membrane removal followed by refill with a different membrane type. In the present study, bilayers of unique composition fill 1 x 1 mum corrals and were positioned 100 nm apart. 相似文献
74.
[reaction: see text] Exposure of any of several mono- or bidentate phosphines to CuCl leads to quick removal of unwanted ligands from solution. Most phosphines, if desired, can be easily recovered. 相似文献
75.
Fordyce A. Davidson Bryan P. Rynne 《Journal of Mathematical Analysis and Applications》2004,300(2):491-504
Let TR be a time-scale, with a=infT, b=supT. We consider the nonlinear boundary value problem (2) (4)
u(a)=u(b)=0,