The effect of inharmonic partials on pitch of piano tones

Piano tones have partials whose frequencies are sharp relative to harmonic values. A listening test was conducted to determine the effect of inharmonicity on pitch for piano tones in the lowest three octaves of a piano. Nine real tones from the lowest three octaves of a piano were analyzed to obtain frequencies, relative amplitudes, and decay rates of their partials. Synthetic inharmonic tones were produced from these results. Synthetic harmonic tones, each with a twelfth of a semitone increase in the fundamental, were also produced. A jury of 21 listeners matched the pitch of each synthetic inharmonic tone to one of the synthetic harmonic tones. The effect of the inharmonicity on pitch was determined from an average of the listeners' results. For the nine synthetic piano tones studied, pitch increase ranged from approximately two and a half semitones at low fundamental frequencies to an eighth of a semitone at higher fundamental frequencies.     

The effect of amplitude envelope on the pitch of sine wave tones

Psychophysical experiments show that the pitch of a short sine wave tone depends upon the amplitude envelope of the tone. Subjects find that the pitch of an exponentially decaying tone (1dB/ms) is higher than the pitch of a (20-ms) rectangularly gated tone of equal frequency. The percentage difference in frequency required to produce equal pitches with the two envelopes depends upon frequency fo: 2.6% at fo = 412 Hz, 1.4% at fo = 825 Hz, 1% at fo = 1650 Hz, and 0.7% at fo = 3300 Hz. The pitch change is insensitive to the relative intensities of the two tones. The spectra of tones with the two different envelopes suggest no obvious explanation for the pitch change. However, the weighted time-varying spectra for tones with two different envelopes evolve differently with time. Alternatively the pitch change can be derived from a modified version of the auditory phase theory of Huggins.     

不同语调条件下的声调音高实现

从调类个性、句中位置和重音级别3个层面的语音分析,考察普通话4个声调在不同语调条件下的音高实现。目标词被置于3种不同的焦点位置(即句重音最强的位置)和两种不同的非焦点位置(即非句重音位置)上,对目标词的调域以及目标声调的高音点和低音点进行了观察分析。实验结果表明,(1)在焦点条件以及非焦点条件下,阳平的音高位于调域的中低音区,去声低音点的理论调值尽管低于阳平低音点,但去声低音点在音高实现上往往接近阳平低音点甚至会高于阳平低音点;(2)焦点在句首位置表现为调域向上下两个方向扩展,在句末位置则表现为调域整体上抬,但不同声调的高音点并不都与调域上限同比例变化,不同声调低音点的变化也并不都与调域下限同比例变化;(3)重音后音节的音高对焦点音节的依赖关系受音步组合关系的制约,焦点和焦点后音节若在同一音步内,焦点后音节的音高与焦点音节的音高关系类似轻声音节与其前接非轻声音节的音高关系,焦点和焦点后音节之间如果存在音步边界,焦点后音节的音高表现出一定的独立性。这些结果说明了语句中声调音高实现的复杂性,一个具有较好预测性的汉语普通话语调模型的建立需要包括焦点结构、韵律结构、协同发音、调类个性等不同层面信息的诸多细节化规则。     

不同语调条件下的声调音高实现

从调类个性、句中位置和重音级别3个层面的语音分析,考察普通话4个声调在不同语调条件下的音高实现。目标词被置于3种不同的焦点位置(即句重音最强的位置)和两种不同的非焦点位置(即非句重音位置)上,对目标词的调域以及目标声调的高音点和低音点进行了观察分析。实验结果表明,(1)在焦点条件以及非焦点条件下,阳平的音高位于调域的中低音区,去声低音点的理论调值尽管低于阳平低音点,但去声低音点在音高实现上往往接近阳平低音点甚至会高于阳平低音点;(2)焦点在句首位置表现为调域向上下两个方向扩展,在句末位置则表现为调域整体上抬,但不同声调的高音点并不都与调域上限同比例变化,不同声调低音点的变化也并不都与调域下限同比例变化;(3)重音后音节的音高对焦点音节的依赖关系受音步组合关系的制约,焦点和焦点后音节若在同一音步内,焦点后音节的音高与焦点音节的音高关系类似轻声音节与其前接非轻声音节的音高关系,焦点和焦点后音节之间如果存在音步边界,焦点后音节的音高表现出一定的独立性。这些结果说明了语句中声调音高实现的复杂性,一个具有较好预测性的汉语普通话语调模型的建立需要包括焦点结构、韵律结构、协同发音、调类个性等不同层面信息的诸多细节化规则。     

翼前缘层板对流冷却结构的防热效果分析

针对飞行器高超声速飞行时严重的气动加热环境, 设计一种层板对流冷却结构对翼前缘进行热防护. 提出一种壁面冷却效率参数η, 并运用流固耦合的分析方法, 研究了对流冷却结构在特定条件下的冷却效果, 其中采用水冷时头部冷却效率η 值最低为0.25. 研究表明, 对流结构冷却效果与内部冷却槽道深宽比γ 有重要关系, η值随γ 的增大而增大至一个稳定值, 此时冷却效果达到饱和, 若此时γ 继续增加则可能出现不利于冷却的现象. 冷却效果η随着前缘头部半径的减小而减弱. 研究还表明, 当层板对流冷却结构和材料固定时, η 值随冷却剂流量增加而增大, 并逐渐趋近至一个稳定值, 而冷却槽道进出口压差急剧增大. 因此需要综合考虑提高流量给供给系统带来的压力, 选取最佳流量值以达到相对较好的冷却效果. 对于材料而言, 内部冷却通道和外部耐热层都应选择导热系数较高的材料, 能够强化结构传热增强冷却效果.     

The effect of a permanent dipole moment on the polar molecule cavity quantum electrodynamics

A dressed-state perturbation theory beyond the rotating wave approximation(RWA) is presented to investigate the interaction between a two-level electronic transition of polar molecules and a quantized cavity field. Analytical expressions can be explicitly derived for both the ground- and excited-state-energy spectrums and wave functions of the system, where the contribution of permanent dipole moments(PDM) and the counter-rotating wave term(CRT) can be shown separately.The validity of these explicit results is discussed by comparison with the direct numerical simulation. Compared to the CRT coupling, PDM results in the coupling of more dressed states and the energy shift is proportional to the square of the normalized permanent dipole difference, and a greater Bloch–Siegert shift can be produced in the giant dipole molecule cavity QED. In addition, our method can also be extended to the solution of the two-level atom Rabi model Hamiltonian beyond the RWA.     

The effect of modulation rate on the detection of frequency modulation and mistuning of complex tones

Experiment 1 measured frequency modulation detection thresholds (FMTs) for harmonic complex tones as a function of modulation rate. Six complexes were used, with fundamental frequencies (F0s) of either 88 or 250 Hz, bandpass filtered into a LOW (125-625 Hz), MID (1375-1875 Hz) or HIGH (3900-5400 Hz) frequency region. The FMTs were about an order of magnitude greater for the three complexes whose harmonics were unresolved by the peripheral auditory system (F0 = 88 Hz in the MID region and both F0s in the HIGH region) than for the other three complexes, which contained some resolved harmonics. Thresholds increased with increases in FM rate above 2 Hz for all conditions. The increase was larger when the F0 was 88 Hz than when it was 250 Hz, and was also larger in the LOW than in the MID and HIGH regions. Experiment 2 measured thresholds for detecting mistuning produced by modulating the F0s of two simultaneously presented complexes out of phase by 180 degrees. The size of the resulting mistuning oscillates at a rate equal to the rate of FM applied to the two carriers. At low FM rates, thresholds were lowest when the harmonics were either resolved for both complexes or unresolved for both complexes, and highest when resolvability differed across complexes. For pairs of complexes with resolved harmonics, mistuning thresholds increased dramatically as the FM rate was increased above 2-5 Hz, in a way which could not be accounted for by the effect of modulation rate on the FMTs for the individual complexes. A third experiment, in which listeners detected constant ("static") mistuning between pairs of frequency-modulated complexes, provided evidence that this deterioration was due the harmonics in one of the two "resolved" complexes becoming unresolved at high FM rates, when analyzed over some finite time window. It is concluded that the detection of time-varying mistuning between groups of harmonics is limited by factors that are not apparent in FM detection data.     

The effect of a surface impedance load on the behavior of quasi-Rayleigh waves near a cylindrical cavity

The effect of a surface impedance load on the properties of axisymmetric quasi-Rayleigh waves propagating along the boundaries of a cylindrical cavity is investigated. By solving the problem by means of the impedance method, a dispersion equation for these waves is obtained. It is shown that the equation can be represented as the condition that the determinant of the sum of impedance matrices of the load and the medium is zero. Analysis of this equation allows one to investigate the effect of the surface load on the behavior of quasi-Rayleigh waves and on their critical frequencies. The conditions that should be met by the impedance load for quasi-Rayleigh waves to be absent near the cavity or for one or two such waves to exist are determined. The choice of the load is specified for the propagating quasi-Rayleigh wave to possess preset dispersion properties. The conclusions drawn on the basis of this study are illustrated by several examples of load models that can be implemented in practice.     

The effect of large openings on cavity amplification at ultrasonic frequencies

It is sometimes desired to exploit acoustic amplification in a cavity that is not entirely enclosed. Because of the presence of openings in the cavity, acoustic energy will leave the cavity and degrade the degree of amplification. The extent of this problem is unknown when the size of the openings becomes large relative to a wavelength. The present paper describes a quantitative estimation of the effect of large openings on the amplification performance of an acoustic cavity. Air was assumed to be the working medium. The amplification taking place in a rigid-walled rectangular channel excited by a transducer flush-mounted in one wall was compared to the amplification that would take place in a bounded rectangular resonator excited by the same transducer. It was found, for frequencies in the range 25 kHz-1 MHz, that source ka's greater than 37 and 42 were required in order for the collimation of the transducer beam to overcome the leakage of acoustic energy through the openings for one- and two-half wavelength resonances, respectively. Experimental measurements conducted over source ka's ranging from 6.5 to 26.1, resulted in quality factors 8%-18% lower than theoretically predicted values for one-, two-, and three-half wavelength resonances.     

The effect of cavity geometry on the nucleation of bubbles from cavities

The heterogeneous nucleation of gas bubbles from cavities in a surface in contact with a liquid is a widely recognized phenomenon. This process has previously been theoretically analyzed extensively for a conical crevice, although in practice a wide range of cavity geometries might be expected. The method of analysis originally presented by Atchley and Prosperetti [J. Acoust. Soc. Am. 86, 1065-1084 (1989)] for the unstable growth of a gas-liquid interface in a conical crevice is here extended to any axisymmetric cavity geometry and four such different geometries are analyzed. Although the method presented neglects gas transfer, and therefore is most directly suitable for acoustic cavitations, this method is still valuable in comparing the nucleation behavior of different cavity types. It is found that once the interface has emerged outside the cavity, its behavior is determined by the size of the cavity's opening. Given that the behavior of the interface once it is outside the cavity will also be determined by the local flow conditions, the threshold for unstable growth of the interface inside the cavity leading to its emergence is the important value and will determine differences between cavity geometries in practice, as shown in the examples presented.     

The effect of parametric oscillatory instability in a Fabry-Perot cavity of the Einstein telescope

The nonlinear effect of a parametric oscillatory instability in a Fabry-Perot cavity of the Einstein Telescope is investigated. Unstable combinations of elastic and optical modes are calculated for two possible configurations of the third-generation gravitational-wave detector. The results are compared with those for the LIGO gravitational-wave interferometer.     

The perceptual attack time of musical tones

Perceptual attack time (PAT) is defined as the time a tone's moment of attack or most salient metrical feature is perceived relative to its physical onset. Experiments are described that measured the PATs of recorded orchestral instrument tones by means of an interactive procedure with a computer and digital music synthesizer. Some PAT prediction models were then developed and tested against the empirical data. The most successful model had a correlation of 0.995 between measured and predicted PATs. The PAT is dependent on both rise time and listening level, indicating that the slope of the rise function is a key factor. Duration and spectrum can also act as cues to PAT, but are much less influential than amplitude or intensity cues. Possible relations to findings in physiology, particularly to the phenomenon of short-term adaptation in the firing of auditory fibers, are discussed.     

Modeling and effect of distortion product generated by harmonic complex tones

To study deeply the effect of distortion product on auditory perception, a functional model is proposed to generate distortion products at frequencies below those of primary stimuli. The operations include calculating different power of the stimuli, low pass filtering, searching optimum weights, and summing the weighted signals across all filtering channels. The model uses simulate annealing and genetic algorithm to search the globally optimum weights. Moreover, this paper studies the effect of distortion products on pitch perception for unresolved harmonics based on the proposed model. Results find that distortion products could enhance the resolvability and temporal information of the harmonics. Thus, it is suggested to use background noise with appropriate sound levels to mask distortion products to reduce the effect on pitch perception.     

The effect of accelerating cavity’s transients on the particle energy spread

An accelerating resonator loaded by current is analyzed based on an equation for normalized amplitude of the oscillations obtained by the method of counterpropagating waves. An expression for the accelerating voltage is derived with allowance for transients observed upon enabling the generator and beam. The effect of transients on the particle energy spread is taken into account. A possibility of stabilizing the beam energy at an arbitrary phase of the generator and without detuning the accelerating resonator in the process of transition to the steady state is demonstrated.     

Wake structure of a deformable Joukowski airfoil

We examine the vortical wake structure shed from a deformable Joukowski airfoil in an unbounded volume of inviscid and incompressible fluid. The deformable airfoil is considered to model a flapping fish. The vortex shedding is accounted for using an unsteady point vortex model commonly referred to as the Brown-Michael model. The airfoil’s deformations and rotations are prescribed in terms of a Jacobi elliptic function which exhibits, depending on a dimensionless parameter m, a range of periodic behaviors from sinusoidal to a more impulsive type flapping. Depending on the parameter m and the Strouhal number, one can identify five distinct wake structures, ranging from arrays of isolated point vortices to vortex dipoles and tripoles shed into the wake with every half-cycle of the airfoil flapping motion. We describe these regimes in the context of other published works which categorize wake topologies, and speculate on the importance of these wake structures in terms of periodic swimming and transient maneuvers of fish.     

The effect of nonadiabaticity on the efficiency of quantum memory based on an optical cavity

Photoluminescence of CdSe colloidal nanocrystals of different topologies in an external electric field has been studied. It has been found that quenching of photoluminescence, which takes place in quantum dots, is proportional to the square of the field, and in elongated nanocrystals quenching of photoluminescence is proportional to the square root. A physical model of the mechanism of quenching based on tunneling of free charges through potential barrier nanocrystal/matrix has been proposed.     

Enhancement of the Kerr effect for a quantum dot in a cavity

Nonlinear susceptibility of a quantum dot (QD) embedded in a two-sided cavity, is studied theoretically from a weak-coupling to a strong-coupling regime. In the relevance of a quantum logic gate, the corresponding nonlinear phase shifts (Kerr effect) are estimated for coherent wavepackets including one photon on average. In the weak-coupling regime, the phase shift enhances strongly as a function of a coupling constant between the cavity photon and QD, and eventually saturates in the strong-coupling regime. We also show transmission spectra to evaluate the efficiency of the phase shift. Although the efficiency decreases monotonically in the weak-coupling regime, it rises in the strong-coupling regime.     

The effect of external cavity reflectivity on the dynamic behaviors of quantum cascade laser

The effect of external reflectivity on the dynamic behaviors of quantum cascade laser coupled to external cavity is theoretically investigated. Our model is based on three-level rate equations including the dependence of the loss on external cavity parameters. We find in particular that the effective reflectivity, photon lifetime and threshold current are strongly influenced by the external cavity length and external reflectivity. The optimum external cavity length (L_ext) is about 4?cm. We also show that the external cavity reflectivity influences significantly the dynamics of the electron number in the upper and lower laser levels, population inversion, and photon numbers in the Fabry Perot and in the external cavities. In addition, the external cavity reflectivity dependences of turn-on delay time (t_th) is also studied and discussed.