普通话中语段重音对小句声学特征的调节

对汉语普通话新闻语篇朗读语料的分析表明,被置于语段中的小句,作为重音标志的音高和音长将发生变化。语段小句与孤立小句相比,音高变化集中表现在小句调核上,是高音点的整体降低,而不同类别的重音,音高降低的程度不同。在语段中,非语段重音的小句重音呈现出较明显的弱化,即表现为音高降低和音节时长缩短。在多个小句构成的语段中,说话人可以利用各小句重音的强弱变化来实现对语段的韵律调节,进而实现对语篇韵律的整体控制和顺畅的语义表达。语段重音及小句重音的研究将实验语音学引进了播音语言教学,也有助于汉语合成语音的韵律控制。      

The influence of discourse hierarchy on the acoustic manifestation of focus in standard Chinese

A phonetic experiment was conducted to investigate whether the acoustic features of discourse focus were subjected to the influence of discourse hierarchy.Six speakers were instructed to read aloud 32 groups of experimental material.The duration,pitch range,f0 maxima,and f0 minima of foci in different discourse hierarchies were extracted for statistical analysis.The results revealed that foci embedded higher in the discourse hierarchy had relatively longer duration and more expanded pitch range;moreover,with the variation of tone combination,foci in different discourse hierarchies differed remarkably in their manifestation of f0 maxima and f0 minima features.Specifically speaking,for non-low tone combinations, foci in higher discourse hierarchy were pronounced with higher f0 maxima,while for low-tone combinations,foci in higher discourse hierarchy were articulated with lower f0 minima.     

Effects of the salience of pitch and periodicity information on the intelligibility of four-channel vocoded speech: implications for cochlear implants

Recent simulations of continuous interleaved sampling (CIS) cochlear implant speech processors have used acoustic stimulation that provides only weak cues to pitch, periodicity, and aperiodicity, although these are regarded as important perceptual factors of speech. Four-channel vocoders simulating CIS processors have been constructed, in which the salience of speech-derived periodicity and pitch information was manipulated. The highest salience of pitch and periodicity was provided by an explicit encoding, using a pulse carrier following fundamental frequency for voiced speech, and a noise carrier during voiceless speech. Other processors included noise-excited vocoders with envelope cutoff frequencies of 32 and 400 Hz. The use of a pulse carrier following fundamental frequency gave substantially higher performance in identification of frequency glides than did vocoders using envelope-modulated noise carriers. The perception of consonant voicing information was improved by processors that preserved periodicity, and connected discourse tracking rates were slightly faster with noise carriers modulated by envelopes with a cutoff frequency of 400 Hz compared to 32 Hz. However, consonant and vowel identification, sentence intelligibility, and connected discourse tracking rates were generally similar through all of the processors. For these speech tasks, pitch and periodicity beyond the weak information available from 400 Hz envelope-modulated noise did not contribute substantially to performance.     

The roles of pitch and duration in sentence accent of Chinese discourse

Relying on a corpus of thirty narrative discourses,the roles of pitch and duration of prosodic words in sentence accent were studied in discourse context.At first,the pitch was normalized.Then according to the pitch range,the sentence and prosodic word were classified into three ranks of strengthened,normal and weakened respectively.In the same time the sentence accent was classified into two levels of primary and secondary by perceptual evaluation. The results showed that the relative pitch range of prosodic words in opposition to sentence contributed dominantly to sentence accent.Furthermore,the roles of pitch and duration in sentence accent were affected interactively by the rank of sentence and prosodic words.In normal prosodic words,primary sentence accents were realized by the mutual performance of pitch and duration while secondary sentence accents mainly depended on the variation of pitch. In strengthened prosodic words,the role of duration in sentence accent was more significant when the pitch range of the sentence was more compressed.Finally,it was found that the correlation between pitch and duration was influenced primarily by the strength of prosodic words,and in weakened,normal and strengthened prosodic words,the correlations between pitch and duration were positive,null,and negative respectively.     

Experimental investigations to establish acoustic fatigue design charts

The investigations presented in this paper show that the acoustically induced stresses in stiffened panels can be estimated with sufficient accuracy. Due consideration is given to the effect of the parameters aspect ratio, stringer pitch, curvature, skin thickness and skin doublers. The stresses can be evaluated by means of random SN curves for different joining techniques.     

Effects of signal envelope on the pitch of short complex tones

Envelope-induced pitch shifts were measured for exponentially decaying complex tones consisting of two sinusoidal components with frequencies f1 = nf0 + 50 Hz and f2 = (n + 1) f0 + 50 Hz, where n equals 3, 4, or 5 and exponential decay rates were 0, 0.5, 1, and 2 dB/ms. Four subjects adjusted a sinusoidal comparison tone to match the virtual pitch of the (missing) fundamental and the pitches of the lower and upper partials f1 and f2. Pitch shifts for f1 are generally less, and pitch shifts for f2 always greater, than envelope-induced shifts observed in isolated sinusoidal tones of comparable frequency and envelope decay rate. Pitch-shift functions for virtual pitch are similar in magnitude and shape to average pitch-shift functions of the partials, which supports the idea that virtual pitch depends on spectral pitch.     

Perception of pitch location within a speaker's range: Fundamental frequency, voice quality and speaker sex

How are listeners able to identify whether the pitch of a brief isolated sample of an unknown voice is high or low in the overall pitch range of that speaker? Does the speaker's voice quality convey crucial information about pitch level? Results and statistical models of two experiments that provide answers to these questions are presented. First, listeners rated the pitch levels of vowels taken over the full pitch ranges of male and female speakers. The absolute f0 of the samples was by far the most important determinant of listeners' ratings, but with some effect of the sex of the speaker. Acoustic measures of voice quality had only a very small effect on these ratings. This result suggests that listeners have expectations about f0s for average speakers of each sex, and judge voice samples against such expectations. Second, listeners judged speaker sex for the same speech samples. Again, absolute f0 was the most important determinant of listeners' judgments, but now voice quality measures also played a role. Thus it seems that pitch level judgments depend on voice quality mostly indirectly, through its information about sex. Absolute f0 is the most important information for deciding both pitch level and speaker sex.     

Dial A440 for absolute pitch: absolute pitch memory by non-absolute pitch possessors

Listeners without absolute (or "perfect") pitch have difficulty identifying or producing isolated musical pitches from memory. Instead, they process the relative pattern of pitches, which remains invariant across pitch transposition. Musically untrained non-absolute pitch possessors demonstrated absolute pitch memory for the telephone dial tone, a stimulus that is always heard at the same absolute frequency. Listeners accurately classified pitch-shifted versions of the dial tone as "normal," "higher than normal" or "lower than normal." However, the role of relative pitch processing was also evident, in that listeners' pitch judgments were also sensitive to the frequency range of stimuli.     

Tuning natural modes of vibration by prestress in the design of a harmonic gong

Prestresses are purposefully added to an object to improve its performance, such as tuning a guitar string by adding tension. This paper reports how the normal modes of a sheet metal component can be tuned through the prestresses generated by cold-forging small dimples. Finite element analysis showed that the frequencies of specific mode shapes were differentially affected by the location of residual stress fields due to dimple formation in relation to modal stress fields. The frequencies of overtones were most sensitive to the depth of the dimples located near the maxima of modal stresses. Using this approach a series of musical gongs were designed with up to the first five overtones tuned to within 5% of the harmonic series. The balance of harmonic and inharmonic overtones in these gongs that are well resolved by the human cochlea may constitute a set of recognizable musical timbres with sufficient harmonicity to produce an unambiguous pitch for most listeners. Since many other mechanical properties of sheet metal components are affected by residual stresses this manufacturing technique may have broader application in design engineering.     

Speaker-independent recognition of Chinese tones

This paper presents a reliable speaker-independent method of recog-nizing Chinese tones.An unbiased center-clipping autocorrelation algorithm ofpitch period extraction is proposed.A two-dimensional decision vector is usedfor recognizing Chinese tones by passing the pitch period sequence through theprocedures of data selection,error correction,data smoothing and curve fitting.The average correct rate of tone recognition for isolated Chinese syllables isover 98%.     

Phase stresses induced by the γ → α transformation in an iron polycrystal

The evolution of the phase stresses induced in the course of the γ ? α transformation in polycrystalline iron is analyzed in the framework of the elastoplastic model of a spherical inclusion. The isolated regions of the α phase (ferrite) and the γ phase (austenite) are treated as inclusions at the initial and final stages of the transformation, respectively. The stresses are calculated with due regard for the plastic flow in a spherical layer (matrix) around these inclusions. The calculated dependence of the hydrostatic phase stresses on the volume fraction of ferrite suggests that these stresses retard the initial stage and promote the final stage of the transformation.     

Main melody extraction from polyphonic music based on modified Euclidean algorithm

Extracting main melody from polyphonic music is one of the most appealing and challenging tasks in music information retrieval (MIR). In this paper, a new melody extraction method based on a modified Euclidean algorithm (MEA) is proposed. Firstly, the instantaneous frequency is adopted to gain better frequency discrimination, and the frame-wise pitch candidates are estimated based on the modified Euclidean algorithm. Next, the candidate trajectories are formed using these potential candidates, and padded by the candidate one octave above or below if there is a gap at some isolated frames. Finally, the melodic contours are extracted using the melody smoothness and salience principle. The proposed modified Euclidean algorithm can deal with diverse coprime harmonic combinations, and work well at low computational cost and memory requirement. The experimental results show that the proposed method can extract main melody extraction effectively with few pitch candidates.     

Contrastive analysis on tone between Putonghua and Taiwan Mandarin

The differences of the pitch and duration of Chinese syllables between Putonghua （PTH） and Taiwan Mandarin （TM） were studied. The speech materials to be used are not only isolated syllables, but also sentences. The results reveal that： For the isolated syllables, T1 and T2 in TM are influenced by Minnan dialect, therefore their pitch are lower than those in PTH. T3 is fall-rise in PTH, while it is fall in TM. Moreover, the syllable duration sequence for different tone is T3〉T2〉T1〉T4 in PTH, while it is T1〉T2〉T3〉T4 in TM. For the syllables in sentences, T2 is mid-rise in PTH, while it is mid-level in TM. And the T3 is longer than T4 but shorter than T1 or T2 in PTH, while it is the shortest in TM. Furthermore the effects of prosodic phrase boundary on duration for different tones are almost the same in PTH, but the lengthening part of T1 or T2 is longer than that of T3 or T4 in TM.     

Influence of pitch, loudness, and timbre on the perception of instrument dynamics

The effect of variations in pitch, loudness, and timbre on the perception of the dynamics of isolated instrumental tones is investigated. A full factorial design was used in a listening experiment. The subjects were asked to indicate the perceived dynamics of each stimulus on a scale from pianissimo to fortissimo. Statistical analysis showed that for the instruments included (i.e., clarinet, flute, piano, trumpet, and violin) timbre and loudness had equally large effects, while pitch was relevant mostly for the first three. The results confirmed our hypothesis that loudness alone is not a reliable estimate of the dynamics of musical tones.     

Ring defects in a strongly confined chiral liquid crystal

We find numerically that a regular array of isolated ring defects can exist as a stable state in a highly chiral liquid crystal confined in a thin cell imposing fixed planar anchoring at the parallel confining surfaces. This peculiar defect structure can be stable when the cell thickness d is around 3/4 of the helical pitch p. A cell of thickness 3p/4 with parallel surface anchoring is incompatible with helical alignment that favors d=mp/2 (with m being an integer). Formation of ring defects can thus be regarded as a result of frustrations between the helical alignment with a specific pitch and the confining surfaces that prevent it.     

Perceived pitch of whispered vowels-relationship with formant frequencies: A preliminary study

To clarify the role of formant frequency in the perception of pitch in whispering, we conducted a preliminary experiment to determine (1.) whether speakers change their pitch during whispering; (2.) whether listeners can perceive differences in pitch; and (3.) what the acoustical features are when speakers change their pitch. The listening test of whispered Japanese speech demonstrates that one can determine the perceived pitch of vowel /a/ as ordinary, high, or low. Acoustical analysis revealed that the perception of pitch corresponds to some formant frequencies. Further data with synthesized whispered voice are necessary to confirm the importance of the formant frequencies in detail for perceived pitch of whispered vowels.     

Effects of signal envelope on the pitch of short sinusoidal tones

The pitch of short sinusoidal tones with exponentially rising or decaying envelopes is judged higher than the pitch of a gated tone of the same frequency, duration, and energy. The upward pitch shift depends on the rise or decay rate, the intensity, and the frequency. The effect, which requires a nonlinearity in the auditory system, cannot be adequately explained by existing models of hearing. Control experiments on pitch matching for short tones of varying duration and varying intensity are described. These suggest that envelope-induced pitch effects are linked to changes in average intensity, so that they are essentially the same as intensity-induced pitch changes. A model based on these considerations is proposed.     

传输矩阵法在行波管内部反射引起的增益波动计算中的应用

本文分析了由于行波管慢波结构制造误差引入的多个不连续点对小信号增益的影响.行波管内部反射对增益波动的影响,须采用考虑反射波的四阶模型进行分析,用传输矩阵法对节点处的自左至右入射和自右至左入射两种散射类型建立传输矩阵,研究在不同空间电荷参量下,慢波电路的单个反射节点以及慢波电路的皮尔斯速度参量b和增益参量C的多个随机分布不连续性对行波管小信号增益的影响,计算结果与Chernin模型具有很好的一致性.并以G波段行波管为例分析了慢波结构周期长度分布有两个不连续点和周期长度的多个随机分布不连续性带来的小信号增益波动.结果表明,制造误差越大,周期长度分布的两个不连续点相距越远,小信号增益波动越大,多个小的不连续性可以引起较大的增益波动.     

Pitch discrimination of harmonic complex signals: residue pitch or multiple component discriminations?

Two models for pitch discrimination of harmonic complex sounds are discussed, a multiple-band probability summation model using comparisons among component frequencies, and a model in which residue pitches are compared. The second model is based on Goldstein's optimum-processor pitch theory [J. Acoust. Soc. Am. 54, 1496-1516 (1973)], and is distinguished from the multiple-band model by an internal noise process. Pitch difference limens from 2I2AFC tasks show that when the test signals comprise corresponding harmonics, relative pitch difference limens are less than the smaller relative difference limens for the component frequencies, which is consistent with the multiple-band model. The absence of corresponding harmonics significantly reduces relative pitch discriminability; this effect supports the model on Goldstein's theory. It appears that residue pitch comparisons are not used for pitch discrimination between sounds with corresponding components; rather, comparisons based on residue pitch are only employed where there are no common resolved components in the signals to be discriminated.     

A psychophysical pitch function determined by absolute magnitude estimation and its relation to the musical pitch scale

A psychophysical pitch function, describing the relation of perceived magnitude of pitch to the frequency of a pure tone, was determined by absolute magnitude estimation. Pitch estimates were made by listeners with relative pitch and by absolute pitch possessors for 27 tones spanning a frequency range of 31.5-12,500 Hz in 1/3 octave steps. Results show that the pitch function, plotted in log-log coordinates, is steeper below 200 Hz than at higher frequencies. It is hypothesized that the pitch function's bend may reflect the diversity of neurophysiological mechanisms of pitch encoding in frequency ranges below and above 200 Hz. The variation of the function's slope implies that pitch distances between tones with the same frequency ratios are perceived as larger below 200 Hz than at higher frequencies. It is argued that this implication may apply only to a purely sensory concept of pitch distance and cannot be extended to the perception of musical intervals, a phenomenon governed by musical cognitive principles. The results also show that pitch functions obtained for listeners with relative and absolute pitch have a similar shape, which means that quantitative pitch relations determined for both groups of listeners do not differ appreciably along the frequency scale.