共查询到20条相似文献,搜索用时 0 毫秒
1.
The need for standardization of procedures in approaches to voice measurement has been recently emphasized. The purpose of this study was to determine the extent to which the acoustic perturbation measurements from three different analysis systems agree when standardized recording and analysis procedures are used. High-quality acoustic voice recordings from 20 patients were analyzed. The results showed that, although fundamental frequency measurements were in strong agreement among the three systems tested, frequency and amplitude perturbation measurements were not in agreement. The underlying approaches to perturbation measurement appeared to be sufficiently different to produce different results. An argument is made for a standardized set of acoustic signals representing normal, dysphonic, and synthesized voices with known characteristics to facilitate testing of new acoustic analysis systems and confirm measurement accuracy and sensitivity. 相似文献
2.
Carole T. Ferrand 《Journal of voice》1995,9(4):419-423
The effects of practice on jitter and shimmer were assessed in two groups of normally speaking women. Subjects in both groups sustained trials of /a/ as steadily as possible during a baseline session, two practice sessions, and a transfer session. Subjects in one group received visual and verbal feedback during the practice sessions. Subjects in the other group received no feedback. Shimmer means remained essentially stable over the four sessions for both groups, and no differences were apparent between the groups. Jitter values were significantly different between sessions for both groups, and between the two groups for the practice sessions. These results are consistent with findings from manual performance and retention tasks. The present findings also support a recently developed neurologic model of jitter. 相似文献
3.
The influence of smoothing by spectral dispersion on the beam characteristics in the near field 下载免费PDF全文
The influences of SSD on the beam characteristics in the near held are investigated. Results snow that it the SSD parameters are increased, the laser intensity modulation increases while fluence modulation decreases, which is attributed to the temporal and spatial variation of the SSD pulse phase. The variations of intensity and fluence modulations with the SSD parameters are given. The simulation results are presented along with a method for choosing appropriate SSD parameters according to the variations and the requirements of applications. 相似文献
4.
The purpose of this study was to compare jitter, shimmer, and signal-to-noise ratio (SNR) measures obtained from tape-recorded samples with the same measures made on directly digitized voice samples, with use of the CSpeech acoustic analysis program. Subjects included 30 young women who phonated the vowel /a/ at a comfortable pitch and loudness level. Voice samples were simultaneously recorded and digitized, and the resulting perturbation measures for the two conditions were compared. Results indicated that there were small but statistically significant differences between percent jitter, percent shimmer, and SNR calculated from taped samples compared with the same measures calculated from directly digitized samples. It was concluded that direct digitization for clinical measures of vocal perturbation was most desirable, but that taped samples could be used, if necessary, with some caution. 相似文献
5.
Robert F. Orlikoff 《Journal of voice》1990,4(4):322-328
Modulation of the acoustic amplitude and fundamental frequency of a sustained vowel across the heart cycle was examined via signal-averaging. Ten normal young and ten normal elderly men prolonged phonations of the vowel /a/. Consistent with previous studies, the young men's maximal heart-beat-related frequency and amplitude variations averaged 1.0% and 8.4% of their respective means. Such modulation was estimated to account for 6.6% of the absolute jitter and 11.3% of the shimmer measured in these voice samples. The extent of this systematic variation was significantly greater in the older voices, averaging 2.4% of the mean frequency and 15.4% of the mean amplitude and was estimated to account for approximately 12.9% and 15.8% of their mean absolute jitter and shimmer, respectively. This age-related difference is thought to be a manifestation of involutional changes in laryngeal vascular and soft tissues and in ventilatory biomechanics. 相似文献
6.
典型的光谱角色散技术中,由于光束带宽受限于高效三倍频,因而无法通过增大带宽来进一步改善焦斑均匀性.结合对四色打靶方案和多级相位调制技术的综合分析,提出了多频、多色光谱角色散束匀滑新方案.该方案能在保持高效三倍频基础上,获得带宽有所加宽,光谱包络近似连续的光源,且在远场匀滑上具有更为独特的优势.结果表明,采用束匀滑新方案后,虽然焦斑会有所增大,但其均匀性却得到明显改善;与典型的束匀滑方案相比,该方案能更为有效地抑制热斑,且达到最佳匀滑效果所需的时间有所减短.此外,通过对阵列光栅中子光栅刻线方向的自由组合可以实现多维光谱角色散的效果. 相似文献
7.
8.
Third harmonic generation (THG) of high power laser is discussed in KDP crystals utilized in frequency conversion systems of large laser facilities. The far-field focal spot of the third harmonic wave is presented based on numerical simulation of the nonlinear coupled-wave equations, in which the walk-off and paraxial diffraction are taken into account and the electric field of the fundamental wave (1053 nm, 1ω) pulse is phase and amplitude modulated in spatial domain. Impact of the modulation depth and frequency on the focal spot energy, the side lobes location and conversion efficiency are analyzed in detail. The results show that the side lobes location is equivalently determined by the modulation frequency of both phase modulation and amplitude modulation, while the energy-concentration is decreased mostly because of the 1ω modulation depth. Relatively, the phase modulation plays a more important role than the amplitude modulation in decreasing main lobe energy for different reasons. The phase modulation makes the energy flowing from the main lobe to side lobes, while amplitude modulation not only makes the energy flowing but also decreases tripling efficiency significantly. 相似文献
9.
基于标量衍射理论建立了光谱色散平滑(SSD)、随机相位板(RPP)和偏振匀滑(PS)联用的光束匀滑方案数值仿真模型。以斑纹对比度和偏振度为主要评价参量,利用该模型研究了径向偏振调制的匀滑及消偏振特性。研究表明,径向偏振调制可以有效降低聚焦光斑斑纹对比度和偏振度。使用半波片拼接方式产生近似径向偏振光时,拼接单元数对匀滑及偏振特性影响较小,8片拼接的匀滑效果已与理想径向偏振光几乎一致。对比分析了径向偏振调制、正交偏振调制和双折射楔三种PS方式,结果表明,由于三种PS方式本质上的一致性,光束的匀滑及偏振特性差别较小。 相似文献
10.
Miyazono H Glasberg BR Moore BC 《The Journal of the Acoustical Society of America》2010,128(6):3649-3657
Thresholds (F0DLs) were measured for discrimination of the fundamental frequency (F0) of a group of harmonics (group B) embedded in harmonics with a fixed F0. Miyazono and Moore [(2009). Acoust. Sci. & Tech. 30, 383386] found a large training effect for tones with high harmonics in group B, when the harmonics were added in cosine phase. It is shown here that this effect was due to use of a cue related to pitch pulse asynchrony (PPA). When PPA cues were disrupted by introducing a temporal offset between the envelope peaks of the harmonics in group B and the remaining harmonics, F0DLs increased markedly. Perceptual learning was examined using a training stimulus with cosine-phase harmonics, F0 = 50 Hz, and high harmonics in group B, under conditions where PPA was not useful. Learning occurred, and it transferred to other cosine-phase tones, but not to random-phase tones. A similar experiment with F0 = 100 Hz showed a learning effect which transferred to a cosine-phase tone with mainly high unresolved harmonics, but not to cosine-phase tones with low harmonics, and not to random-phase tones. The learning found here appears to be specific to tones for which F0 discrimination is based on distinct peaks in the temporal envelope. 相似文献
11.
12.
Mikl M Marecek R Hlustík P Pavlicová M Drastich A Chlebus P Brázdil M Krupa P 《Magnetic resonance imaging》2008,26(4):490-503
The analysis of functional magnetic resonance imaging (fMRI) data involves multiple stages of data pre-processing before the activation can be statistically detected. Spatial smoothing is a very common pre-processing step in the analysis of functional brain imaging data. This study presents a broad perspective on the influence of spatial smoothing on fMRI group activation results. The data obtained from 20 volunteers during a visual oddball task were used for this study. Spatial smoothing using an isotropic gaussian filter kernel with full width at half maximum (FWHM) sizes 2 to 30 mm with a step of 2 mm was applied in two levels — smoothing of fMRI data and/or smoothing of single-subject contrast files prior to general linear model random-effects group analysis generating statistical parametric maps. Five regions of interest were defined, and several parameters (coordinates of nearest local maxima, t value, corrected threshold, effect size, residual values, etc.) were evaluated to examine the effects of spatial smoothing. The optimal filter size for group analysis is discussed according to various criteria. For our experiment, the optimal FWHM is about 8 mm. We can conclude that for robust experiments and an adequate number of subjects in the study, the optimal FWHM for single-subject inference is similar to that for group inference (about 8 mm, according to spatial resolution). For less robust experiments and fewer subjects in the study, a higher FWHM would be optimal for group inference than for single-subject inferences. 相似文献
13.
The effects of vowels on voice perturbation measures 总被引:1,自引:0,他引:1
Mehmet Akif Kili? Fatih O?üt Gürsel Dursun Erdo?an Okur Ilhami Yildirim Ra?it Midilli 《Journal of voice》2004,18(3):318-324
This study examines voice perturbation parameters of the sustained [a] in English and of the eight vowels in Turkish to discover whether any difference exists between these languages, and whether a correlation exists between voice perturbation parameters and articulatory and acoustic properties of the Turkish vowels. Eight Turkish vowels uttered by 26 healthy nonsmoker volunteer males who are native Turkish speakers were compared with a voice database that includes samples of normal and disordered voices belonging to American English speakers. Fundamental frequencies, the first and second formants, and perturbation parameters, such as jitter percent, pitch perturbation quotient, shimmer percent, and amplitude perturbation quotient of the sustained vowels, were measured. Also, the first and second formants of the sustained [a] in English were measured, and other parameters have been obtained from the database. When the voice perturbation parameters in Turkish and English were compared, statistically significant differences were not found. However, when Turkish vowels compared with each other, statistically significant differences were found among perturbation values. Categorical comparisons of the Turkish vowels like high-low, rounded-unrounded, and front-back revealed significant differences in perturbation values. In correlation analysis, a weak linear inverse relation between jitter percent and the first formant (r=-0.260, p<0.05) was found. 相似文献
14.
15.
According to the random characteristics of surface distribution of continuous phase plate (CPP), the characteristics of such random surface are analyzed from a statistical point of view. Based on the continuous phase plate with Gaussian distribution, the ergodic theorem is introduced to describe the statistical characteristics of CPP, and the qualification that fulfills the ergodic theorem is proved. The CPP which fulfills the ergodic theorem is proved to have better beam smoothing properties in both spatial and frequency domain by numerical simulation. The results show that after smoothing, the focal spot of random distortion beam is well controlled. The average PSD value of distortion wavefront is decreased by 50% or more. 相似文献
16.
17.
激光频率标准是将激光频率锁定于原子或分子的超精细能级间的跃迁频率,从而获得高精密度的激光频率输出。在激光稳频研究工作中,通常将碘分子的吸收谱线采用导数谱、FM光谱和调制转移光谱MTS(ModulationTransferSpectroscopy)进行频率的精密控制。为更好地消除吸收谱线的本底噪声,目前最好的稳频方案是采用调制转移光谱法。它具有高灵敏度、高分辨率和无多普勒背景等特点。从物理学的原理出发,分析了激光对介质的极化机理,导出介质对激光的吸收和色散作用的数学模型,用信号处理的技术从理论上推导了MTS谱线线型,分析了光谱线型的特性,讨论了提高激光频率稳定度的各种情况。 相似文献
18.
在图像处理过程中, 为了在图像去噪时更好地保留图像边缘细节信息, 首先结合扩散系数和曲率的性质建立了一个曲率平滑模型. 考虑到图像受到噪声污染时曲率会发生显著变化, 将图像的水平集曲率作为一个检测因子代入到上述模型中, 提出了一个梯度与曲率相结合的新模型. 分析与仿真结果表明, 该模型与Perona-Malik模型相比较保留了更多的图像信息, 有效地增强了图像尖锐的边缘, 同时很好地保持了图像的直线和曲线边缘、角点、斜坡和小尺度特征, 是一个理想的模型. 相似文献
19.
20.
B L Brown W J Strong A C Rencher 《The Journal of the Acoustical Society of America》1974,55(2):313-318