There is some disagreement in the literature about the relative contribution of formant transition duration and amplitude rise time in cuing the stop-glide distinction (e.g., [b] vs [w]). Lack of resolution on this point is partly due to the confounding of these two variables in most studies. For a series of identification experiments, sets of synthetic [ba] and [wa] stimuli were created in which transition duration and rise time varied orthogonally. Both variables affected labeling performance in the expected direction, but transition duration was by far the more important factor. A similar pattern of results was obtained for single sine-wave stimuli that modeled the rise times, frequency trajectories, and durations of the first formant in the [ba] and [wa] stimuli. A likely auditory basis for both the speech and nonspeech effects is that rapid frequency transitions and short rise times both contribute to a higher degree of spectral splatter (i.e., dispersion of energy across a wide frequency band), which may be a principal cue for abrupt onsets in general. [Work supported by NICHD.]
The purpose of this research project was to gather evidence about the characteristics of embedded [literacy, language and numeracy] LLN teaching and learning. In particular, the project aimed to establish what is meant by 'embedded teaching and learning', how the vocational subjects and the LLN skills relate on such programmes, how subject teachers and LLN teachers work together or how sometimes a single teacher can handle both, and what implications can be drawn for policy and practice. To study all this, it was essential to select a contrasting range of embedded programmes for the case studies. In selecting the case studies, close reference was made to the work of the [Department for Education and Skills] DfES Standards Unit, and to the findings of the Developing Embedded Basic Skills project (DEBS). The project aimed to examine a wide variety of embedded LLN provision to reflect the diversity of vocational courses. The sites for the case studies were selected from the following curriculum areas: land-based; entry to employment (E2E) - engineering; construction; complementary therapy; childcare; and nursing. The courses studied were either standard vocational programmes for young people or specially designed preparatory vocational programmes for adults. The case studies describe examples of embedded approaches at work, and illuminate how embedded LLN can work successfully as an integral part of vocational courses. They also illuminate some of the characteristics critical to this success.
Fowler [J. Acoust. Soc. Am. 88, 1236–1249 (1990)] makes a set of claims on the basis of which she denies the general interpretability of experiments that compare the perception of speech sounds to the perception of acoustically analogous nonspeech sounds. She also challenges a specific auditory hypothesis offered by Diehl and Walsh [J. Acoust. Soc. Am. 85, 2154–2164 (1989)] to explain the stimulus-length effect in the perception of stops and glides. It will be argued that her conclusions are unwarranted.
There is some disagreement in the literature about the relative contribution of formant transition duration and amplitude rise time in signalling the contrast between stops and glides. In this study, listeners identified sets of /ba/ and /wa/ stimuli in which transition duration and rise time varied orthogonally. Both variables affected labelling performance in the expected direction (i.e. the proportion of /b/ responses increased with shorter transition durations and shorter rise times). However, transition duration served as the primary cue to the stop/glide distinction, whereas rise time played a secondary, contrast-enhancing role. A qualitatively similar pattern of results was obtained when listeners made abrupt-onset/gradual-onset judgements of single sine-wave stimuli that modelled the rise times, frequency trajectories, and durations of the first formant in the /ba/-/wa/ stimuli. The similarities between the speech and non-speech conditions suggest that significant auditory commonalities underlie performance in the two cases.
The duration of an adjacent vowel has been demonstrated to affect the judgment of consonant duration and, hence, phonetic identity. For example, syllable-initial stops can be distinguished from glides on the basis of transition duration and, when the following vowel is relatively long, longer transitions are required in order for a glide to be perceived. Apparently, the vowel provides a source of durational contrast, whereby a longer vowel makes the adjacent consonant seem shorter. This effect has been demonstrated for both speech and nonspeech signals [L. Diehl and M. A. Walsh, J. Acoust. Soc. Am. Suppl. 1 80, S125 (1986)], and is presumably grounded in a general auditory mechanism. In this study, the effect of vowel duration on perception of syllable-initial consonants is also demonstrated for fricatives and affricates. Frication duration is an important cue to this distinction, with longer durations yielding more /∫/ responses. Two series of edited natural tokens of /∫a/ and /t∫a/ were created in which frication duration varied from 100 to 210 ms. The duration of the following vowel was 204 ms for one series, and 358 ms for the other. With the longer vowel context, significantly longer frication was required to yield a /∫/ percept. Consistent with earlier findings for other consonantal distinctions, durational contrast occurred between the vowel and fricative. [Work supported by NINCDS.]
This paper describes the perceptual role of frication duration and amplitude rise time in signaling the fricative/affricate distinction in initial position. Sets of edited natural tokens of /∫a/ and /t∫a/ were created in which fricative duration and rise time varied orthogonally. In one experiment, frication duration varied from 100 to 210 ms, and rise time was fixed at either 30 or 80 ms. Frication duration proved to be a robust cue for the fricative/affricate distinction, with longer durations yielding more /∫/ responses. Moreover, the longer value of rise time shifted the /∫/-/t∫/ labeling boundary toward shorter frication durations; thus rise time had an enhancing effect on the perception of the fricative-duration cue. In a second experiment, rise time varied from 20 to 110 ms, while frication duration was fixed at either 140 or 160 ms. Although the fricative-duration parameter had a reliable effect on the percentage of fricative responses, variation in rise time alone had very little effect. These results are analogous to those of Walsh and Diehl [J. Acoust. Soc. Am. Suppl. 1 82, S80 (1987)], who found that transition duration plays a far more significant role than rise time in signaling the stop/glide distinction. [Work supported by NINCDS.]
The purpose of this study was to test the relative efficacy of two modes of instruction for promoting learning and retention of selected geometrical concepts. The subjects in this study consisted of 119 students from three seventh and two eighth grade mathematics classes in Pittsburgh, Pennsylvania. The students in each class were randomly assigned by ability, to either the individualized group or the traditional group. The experiment consisted of five 45‐minute periods per week for approximately six weeks. A 53‐item achievement test was administered to each group at the conclusion of the experiment. The retention test (55 items) was administered three weeks after the completion of the experiment. The results of the study did not indicate a significant effect on learning or retention due to the mode of instruction. There was however a slight trend favouring the individualized group.
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