The effect of voice lessons on the clinical and perceptual skills of graduate students in speech-language pathology

Two groups of 10 speech-language pathology graduate students were each given 7 weeks of singing lessons to determine whether voice lessons could have an effect on their clinical and perceptual skills. Pre-, mid-, and posttests to measure various skills were designed and implemented. With use of paired sample statistical testing, statistically significant results were obtained. In addition, the subjective responses of the students show that the lessons were effective in improving pitch perception, breath control, and legato production or easy onset. This study supports efforts to integrate curricula in vocal performance and speech-language pathology.     

Vowel Intelligibility in Classical Singing

Vowel intelligibility during singing is an important aspect of communication during performance. The intelligibility of isolated vowels sung by Western classically trained singers has been found to be relatively low, in fact, decreasing as pitch rises, and it is lower for women than for men. The lack of contextual cues significantly deteriorates vowel intelligibility. It was postulated in this study that the reduced intelligibility of isolated sung vowels may be partly from the vowels used by the singers in their daily vocalises. More specifically, if classically trained singers sang only a few American English vowels during their vocalises, their intelligibility for American English vowels would be less than for those classically trained singers who usually vocalize on most American English vowels. In this study, there were 21 subjects (15 women, 6 men), all Western classically trained performers as well as teachers of classical singing. They sang 11 words containing 11 different American English vowels, singing on two pitches a musical fifth apart. Subjects were divided into two groups, those who normally vocalize on 4, 5, or 6 vowels, and those who sing all 11 vowels during their daily vocalises. The sung words were cropped to isolate the vowels, and listening tapes were created. Two listening groups, four singing teachers and five speech-language pathologists, were asked to identify the vowels intended by the singers. Results suggest that singing fewer vowels during daily vocalises does not decrease intelligibility compared with singing the 11 American English vowels. Also, in general, vowel intelligibility was lower with the higher pitch, and vowels sung by the women were less intelligible than those sung by the men. Identification accuracy was about the same for the singing teacher listeners and the speech-language pathologist listeners except for the lower pitch, where the singing teachers were more accurate.     

Preparation and characterization of activated carbons from impregnation pitch by ZnCl2

Using an impregnation pitch from bituminous coal tar (OP) supplied by Industrias Químicas del Nalon Company as raw material, two phases (isotropic and anisotropic) have been obtained. The latter was used as precursor for the preparation of activated carbons. First, a chemical activation process was carried out with ZnCl₂ as activating agent. The process was conducted at different concentrations and temperatures and by means of impregnation with solid zinc chloride. Optimal values were obtained for samples prepared by using a ZnCl₂:pitch ratio equal to 3:1 (sample AZn3). Next, this sample was thermally treated at two different temperatures, i.e., 700 and 800 °C. A lose of specific surface area, microporosity and mesoporosity was observed with respect to sample AZn3, such a lose being more remarkable as temperature increased. Moreover, impregnation of the anisotropic phase of the original pitch with an aqueous solution of ZnCl₂ followed by thermal treatment resulted in a poorly developed surface area and porous texture, probably due to the presence of Zn complexes, which interfere with the activation process.     

Characterisation of pitch by HPLC

Summary A new high performance liquid chromatography method for the characterisation of toluene-soluble fractions of pitches has been developed. Although a chromatographic system typical of size exclusion chromatography was used, results indicate that, for these structurally complex samples, separation does not follow the usual discrimination by molecular size. A differentiation between several classes of polyaromatic hydrocarbons is achieved instead. Data are reported on the analysis of individual standard polyaromatic hydrocarbons, showing that four different elution ranges can be observed: three ofcata-condensed compounds (Cata1, Cata2 and Cata3) and one ofperi-condensed compounds (Peri). Results are reported proving the capacity of this high performance liquid chromatography method to distinguish between pitches of different origin and nature. It is also effective for the study of the chemical reactions occurring during heat treatment.     

浅析简易型架空光缆的研制及应用

随着国内外光通信行业的发展,光纤光缆的制造技术也得到了长足的发展,目前管道资源日益紧缺的情况下,架空光缆成为解决管道资源紧张的有效措施之一,尤其是自承式架空光缆借助其施工便利而备受青睐.本文重点介绍简易型架空光缆的结构设计原理、关键制造工艺技术及应用,为光缆小型化低成本提供一定借鉴意义.     

The Role of Pitch Memory in Pitch Discrimination and Pitch Matching

Accurate control of vocal pitch (fundamental frequency) requires coordination of sensory and motor systems. Previous research has supported the relationship between perceptual accuracy and vocal pitch matching accuracy. The purpose of this study was to investigate the role of memory for pitch in pitch matching and pitch discrimination ability. Three experimental tasks were used. First, a pitch matching task was completed, in which the participants listened to target tones and vocally matched the pitch of the tones. The second task was a pitch discrimination task that required the participants to judge the pitch (same or different) of complex tone pairs. The third task was pitch discrimination with memory interference task that was similar to the pitch discrimination task except interference tones were added. Results of the pitch matching and pitch discrimination tasks yielded a significant correlation between these values. When there was memory interference, pitch discrimination ability was poorer, and there was no significant correlation between pitch discrimination and pitch matching. These results support earlier findings of a relationship between pitch discrimination and pitch matching abilities. The results also suggest a possible role of pitch memory in both tasks. These findings may have implications for abilities related to accurate pitch control.     

STATISTICAL FEATURE OF PITCH FREQUENCY DISTRIBUTIONS FOR OBUST SPEAKER IDENTIFICATION

This letter proposes an effective and robust speech feature extraction method based on statistical analysis of Pitch Frequency Distributions (PFD) for speaker identification. Compared with the conventional cepstrum, PFD is relatively insensitive to Additive White Gaussian Noise (AWGN), but it does not show good performance for speaker identification, even if under clean environments. To compensate this shortcoming, PFD and conventional cepstrum are combined to make the ultimate decision, instead of simply taking one kind of features into account. Experimental results indicate that the hybrid approach can give outstanding improvement for text-independent speaker identification under noisy environments corrupted by AWGN.