线性调频Z变换在舱音背景声的特征频率分析中的应用

舱音背景声特征频率的确定是调查失事飞机事故原因的重要依据之一。基于舱音译码辨听和音频分析的传统方法难以准确获得舱音背景声的特征频率。本文提出采用基于FFT的线性Z变换(CZT)来获取舱音背景声的特征频率的新方法,该方法适用于高采样频率的信号,计算中可以调整频率的分辨率,增加了FFT和频谱分析的灵活性。通过仿真和对用舱音记录器测录的真实舱音背景声计算分析得出:CZT方法是一种适合于确定舱音背景声特征频率的实用、有效方法,用以区分不同舱音在频率上的差别,满足飞机事故原因调查的需要。     

基于人耳听觉模型的自动嗓音评估方法

在嗓音评估系统的长元音谐噪比分析中,针对传统方法在普通傅里叶变换域上进行谐波成分计算并且需要对样本进行人工选择切分的情况,提出了一种新谐噪比计算方法,能够自动切分出长元音中稳定部分,并采用了更贴近人耳听觉模型的时频分析办法,使对长元音的分析能够更稳定更贴近人耳主观听觉.同时由于没有人工干预,使得评估标准更加统一,结果更加客观. 关键词： 嗓音评估 听觉模型 长元音分析 谐噪比计算     

An Exploration of Skin Acceleration Level as a Measure of Phonatory Function in Singing

Two kinds of fluctuations are observed in phonetogram recordings of singing. Sound pressure level (SPL) can vary due to vibrato and also due to the effect of open and closed vowels. Since vowel variation is mostly a consequence of vocal tract modification and is not directly related to phonatory function, it could be helpful to suppress such variation when studying phonation. Skin acceleration level (SAL), measured at the jugular notch and on the sternum, might be less influenced by effects of the vocal tract. It is explored in this study as an alternative measure to SPL. Five female singers sang vowel series on selected pitches and in different tasks. Recorded data were used to investigate two null hypotheses: (1) SPL and SAL are equally influenced by vowel variation and (2) SPL and SAL are equally correlated to subglottal pressure (P(S)). Interestingly, the vowel variation effect was small in both SPL and SAL. Furthermore, in comparison to SPL, SAL correlated weakly to P(S). SAL exhibited practically no dependence on fundamental frequency, rather, its major determinant was the musical dynamic. This results in a non-sloping, square-like phonetogram contour. These outcomes show that SAL potentially can facilitate phonetographic analysis of the singing voice.     

Acoustic Changes in Student Actors' Voices After 12 Months of Training

This study was to evaluate acoustic changes in student actors' voices after 12 months of actor training. The design used was a longitudinal study. Eighteen students enrolled in an Australian tertiary 3-year acting program (nine male and nine female) were assessed at the beginning of their acting course and again 12 months later using a questionnaire, interview, maximum phonation time (MPT), reading, spontaneous speaking, sustained phonation tasks, and a pitch range task. Samples were analyzed for MPT, fundamental frequency across tasks, pitch range for speaking and reading, singing pitch range, noise-to-harmonic ratio, shimmer, and jitter. After training, measures of shimmer significantly increased for both male and female participants. Female participants' pitch range significantly increased after training, with a significantly lower mean frequency for their lowest pitch. The finding of limited or negative changes for some measures indicate that further investigation is required into the long-term effects of actor voice training and which parameters of voicing are most targeted and valued in training. Particular investigation into the relationship between training targets and outcomes could more reliably inform acting programs about changes in teaching methodologies. Further research into the relationship between specific training techniques, physiological changes, and vocal changes may also provide information on implementing more evidence-based training methods.     

Should Singing Activities Be Included in Speech and Voice Therapy for Prepubertal Children?

Customarily, speaking and singing have tended to be regarded as two completely separate sets of behaviors in clinical and educational settings. The treatment of speech and voice disorders has focused on the client's speaking ability, as this is perceived to be the main vocal behavior of concern. However, according to a broader voice-science perspective, given that the same vocal structure is used for speaking and singing, it may be possible to include singing in speech and voice therapy. In this article, a theoretical framework is proposed that indicates possible benefits from the inclusion of singing in such therapeutic settings. Based on a literature review, it is demonstrated theoretically why singing activities can potentially be exploited in the treatment of prepubertal children suffering from speech and voice disorders. Based on this theoretical framework, implications for further empirical research and practice are suggested.     

Comparison of acoustic and perceptual measures of voice in male-to-female transsexuals perceived as female versus those perceived as male

The present study explored significant differences between male-to-female transgendered speakers perceived as male and those perceived as female in terms of speaking fundamental frequency (SFF) and its variability, vowel formants for /a/ and /i/, and intonation measures. Fifteen individuals who identified themselves as male-to-female transsexuals served as speaker subjects, in addition to 6 biological female control subjects and 3 biological male control subjects. Each subject was recorded reading the Rainbow Passage and producing the isolated vowels /a/ and /i/. Twenty undergraduate psychology students served as listeners. Results indicated that subjects perceived as female had a higher mean SFF and higher upper limit of SFF than subjects perceived as male. A significant correlation between upper limit of SFF and ratings of femininity was achieved.     

High-resolution cardiac imaging using an interleaved 3D double slab technique

A three-dimensional (3D) gradient-echo sequence with interleaved double-slab excitation was developed and optimized for the requirements in pediatric cardiac imaging. For this purpose high contrast between blood and myocardium signal should be obtained without the use of contrast agents. An acceptable measuring time for a large region examined with high spatial resolution should be achieved as well, especially with regard to the small structures of the heart and vessels of infants. The presented approach works with gradient moment nulling and a short echo time of 5.5 ms resulting in generally high signal intensity and only minor signal losses due to turbulent flow. The sequence allows simultaneous ECG-gated recording of two separately excited slabs with small thickness (10 mm) and with a distance of several centimeters between them. Thus, common effects of presaturation in 3D imaging can be avoided, although a relatively short measuring time is achievable. In order to get a 3D data set with good signal homogeneity of blood and of the other structures across a large volume of interest several double-slab measurements with suitable positions must be performed. The latter aspect is especially important for postprocessing techniques as multiple planar reconstruction and maximum intensity projection. Examples of applications of the new technique and appropriately postprocessed images are presented allowing demonstration even of subtle cardiac malformations.