Amplitude Contours Research Articles

Optical Brewster interfaces enabled object identification and 3D reconstruction

Efficient and accurate object identification and 3D reconstruction are crucial for processing image information in visual imaging. Here, we propose a novel scheme for all-optical 2D contour identification and 3D reconstruction based on optical Brewster interfaces. It is revealed that 2D amplitude and phase contours for high-contrast and low-contrast objects can be identified, which is attributed to the 1D and 2D light fields manipulated by the photonic spin Hall and the Brewster effects. The 3D model can be reconstructed by rotating or slicing the high-contrast objects and by inverting the thickness of the low-contrast objects. The study potentially opens up opportunities in applications such as intelligent driving and microscopic imaging.

Does the sampling frequency of an eye tracker affect the detection of glaucomatous visual field loss?

Evidence suggests that eye movements have potential as a tool for detecting glaucomatous visual field defects. This study evaluated the influence of sampling frequency on eye movement parameters in detecting glaucomatous visual field defects during a free-viewing task. We investigated eye movements in two sets of experiments: (a) young adults with and without simulated visual field defects and (b) glaucoma patients and age-matched controls. In Experiment 1, we recruited 30 healthy volunteers. Among these, 10 performed the task with a gaze-contingent superior arcuate (SARC) scotoma, 10 performed the task with a gaze-contingent biarcuate (BARC) scotoma and 10 performed the task without a simulated scotoma (NoSim). The experimental task involved participants freely exploring 100 images, each for 4 s. Eye movements were recorded using the LiveTrack Lightning eye-tracker (500 Hz). In Experiment 2, we recruited 20 glaucoma patients and 16 age-matched controls. All participants underwent similar experimental tasks as in Experiment 1, except only 37 images were shown for exploration. To analyse the effect of sampling frequency, data were downsampled to 250, 120 and 60 Hz. Eye movement parameters, such as the number of fixations, fixation duration, saccadic amplitude and bivariate contour ellipse area (BCEA), were computed across various sampling frequencies. Two-way ANOVA revealed no significant effects of sampling frequency on fixation duration (simulation, p = 0.37; glaucoma patients, p = 0.95) and BCEA (simulation, p = 0.84; glaucoma patients: p = 0.91). BCEA showed good distinguishability in differentiating groups across different sampling frequencies, whereas fixation duration failed to distinguish between glaucoma patients and controls. Number of fixations and saccade amplitude showed variations with sampling frequency in both simulations and glaucoma patients. In both simulations and glaucoma patients, BCEA consistently differentiated them from controls across various sampling frequencies.

Assessment of radio(chemo)therapy-related dysphagia in head and neck cancer patients based on cough-related acoustic features: a prospective phase II national clinical trial (ACCOUGH-P/A trial)

BackgroundRadiation-associated dysphagia is defined as impaired swallowing efficiency/safety following (chemo)radiotherapy in head and neck cancer patients. In a dysphagia framework, impaired coughing may lead to lung aspiration and fatal lung infection. Although cough efficacy is a predictor of the risk of aspiration, cough investigation is minimal in patients with radiation-associated dysphagia. Because cough is a transient signal, existing software for speech analysis are not appropriate. The goal of our project is to develop an assessment method using acoustic features related to voluntary and reflexive coughs as biomarkers of the risk of penetration/aspiration in patients with radiation-associated dysphagia.MethodsHealthy subjects and head and neck cancer patients with and without dysphagia will produce voluntary coughs, throat clearings and reflexive coughs. Recordings will be made using an acoustic microphone and a throat microphone. The recorded signals will be manually segmented and subsequently analysed with a software under development. Automatic final segmentation enables to measure cough duration. The first method of analysis includes temporal features: the amplitude contour, the sample entropy and the kurtosis. These features report respectively the strength, the unpredictability (turbulence noise due to the air jet) and the impulsive quality (burst) of the signal. The second method of analysis consists of a spectral decomposition of the relative cough signal energy into several frequency bands (0–400 Hz, 400–800 Hz, 800–1600 Hz, 1600–3200 Hz, > 3200 Hz). The primary outcome of this exploratory research project is the identification of a set of descriptive acoustic cough features in healthy subjects as reference data (ACCOUGH). The secondary outcome of this research in head and neck cancer patients with radiation-associated dysphagia includes the identification of (1) a set of descriptive acoustic cough features as biomarkers of penetration-aspiration (ACCOUGH-P/A), (2) swallowing scores, (3) voice features and (4) aerodynamic cough features.DiscussionThis study is expected to develop methods of acoustic cough analysis to enhance the assessment of radiation-associated dysphagia in head and neck cancer patients following (chemo)radiation.Trial registrationInternational Standard Randomized Controlled Trials Number (ISRCTN) registry ISRCTN16540497. Accepted on 23 June 2023.

Acoustic Analysis of Voluntary Coughs, Throat Clearings, and Induced Reflexive Coughs in a Healthy Population.

Cough efficacy is considered a reliable predictor of the aspiration risk in head and neck cancer patients with radiation-associated dysphagia. Currently, coughing is assessed perceptually or aerodynamically. The goal of our research is to develop methods of acoustic cough analysis. In this study, we examined in a healthy population the acoustical differences between three protective maneuvers: voluntary cough, voluntary throat clearing, and induced reflexive cough. Forty healthy participants were included in this study. Voluntary cough, voluntary throat clearing, and reflexive cough samples were recorded and analyzed acoustically.Temporal acoustic features were the following: the slope and curvature of the amplitude contour, as well as the average, slope, and curvature of the sample entropy and kurtosis contours of the recorded signal. Spectral features were the relative energy in the frequency bands (0-400Hz, 400-800Hz, 800-1600Hz, 1600Hz-3200Hz, > 3200Hz) as well as the weighted spectral energy. Results showed that, compared to a voluntary cough, a throat clearing starts with a weaker onset pulse and involves oscillations from the onset to the offset (concave curvature of the amplitude contour, p < 0.05), lower average (p < 0.05), and slope (p < 0.05) as well as lower convex curvature (p < 0.05) of the kurtosis contour. An induced reflexive cough starts with a higher and briefer onset burst and includes higher frication noise (larger convexity of the curvature of the amplitude and kurtosis contours (p < 0.05)) compared to a voluntary cough. The conclusion is that voluntary coughs are acoustically significantly different from voluntary throat clearings and induced reflexive coughs.

Analyses of the spatial and temporal features of the blade pressure‐side cavitation in a pump‐turbine runner in the pump mode

AbstractIn the pump mode of pump‐turbine, cavitation usually happens in runners because of the local pressure drop on the blade leading‐edge. At over‐load, pressure drop and cavitation occur on the runner blade pressure side. In conventional studies, the spatial and temporal features of the blade pressure‐side cavitation are difficult to understand. In this study, the runner blade pressure‐side cavitation is studied in a pump‐turbine in pump mode at over‐load. Local low pressure and cavitation are found on runner blade pressure‐side at leading‐edge near shroud. Moreover, small‐scale gathering cavitation is also observed on the blade suction‐side with connecting the large‐scale pressure side cavity. As a breakthrough in flow analysis, the pulsation tracking network (PTN) method is applied to track the spatial and temporal features of cavitation. The time‐accumulated intensity, pulsation amplitude, frequency, and phase are analyzed for cavitation based on PTN. The stably‐gathering strong‐intensity cavitation sites are indicated by time‐accumulated intensity. Based on the pulsation amplitude contour, strong pulsating cavitation is found on the edges of the gathering strong cavities. Frequency and phase analyses indicate the cavitation propagation along the blade‐to‐blade direction and reveal the reason of the connecting cavitation phenomenon. The spatial and temporal features of cavitation is well investigated.

Non-stereotyped amplitude modulation across signature whistle contours

Bottlenose dolphin signature whistles are characterized by distinctive frequency modulation over time. The stable frequency contours of these whistles broadcast individual identity information. Little is known however, about whether or not the amplitude contour is also stereotyped. Here, we examined the relative amplitude-time contour of signature whistle emissions from eight bottlenose dolphins (Tursiops truncatus) in the U.S. Navy Marine Mammal Program (MMP) in San Diego, CA. The results suggested that unlike the stable frequency-time contour, the amplitude-time contour of signature whistles were largely non-stereotyped, characterized by large variability across multiple whistle emissions. Relative amplitude was negatively related to log peak frequency, with more energy focused in the lower frequency bands. This trend was consistent over all eight dolphins despite having quite different signature whistle contours. This relationship led to the amplitude contours being slightly more stereotyped within than between dolphins. We propose that amplitude across signature whistle emissions may serve as an avenue for encoding additional communicative information. We encourage future studies to incorporate analyses of amplitude contours in addition to frequency contours of signature whistles in order to begin to understand what role it may play in the dolphin communication system.

Mandatory dichotic integration of second-formant information: Contralateral sine bleats have predictable effects on consonant place judgments.

Speech-on-speech informational masking arises because the interferer disrupts target processing (e.g., capacity limitations) or corrupts it (e.g., intrusions into the target percept); the latter should produce predictable errors. Listeners identified the consonant in monaural buzz-excited three-formant analogues of approximant-vowel syllables, forming a place of articulation series (/w/-/l/-/j/). There were two 11-member series; the vowel was either high-front or low-back. Series members shared formant-amplitude contours, fundamental frequency, and F1+F3 frequency contours; they were distinguished solely by the F2 frequency contour before the steady portion. Targets were always presented in the left ear. For each series, F2 frequency and amplitude contours were also used to generate interferers with altered source properties-sine-wave analogues of F2 (sine bleats) matched to their buzz-excited counterparts. Accompanying each series member with a fixed mismatched sine bleat in the contralateral ear produced systematic and predictable effects on category judgments; these effects were usually largest for bleats involving the fastest rate or greatest extent of frequency change. Judgments of isolated sine bleats using the three place labels were often unsystematic or arbitrary. These results indicate that informational masking by interferers involved corruption of target processing as a result of mandatory dichotic integration of F2 information, despite the grouping cues disfavoring this integration.

Ground Penetrating Radar Imaging of a Circular Patterned Ground near King Sejong Station, Antarctica

Constraints on the structure and composition of the active layer are important for understanding permafrost evolution. Soil convection owing to repeated moisture-induced freeze-thaw cycles within the active layer promotes the formation of self-organized patterned ground. Here we present the results of ground penetrating radar (GPR) surveys across a selected sorted circle near King Sejong Station, Antarctica, to better delineate the active layer and its relation to the observed patterned ground structure. We acquire GPR data in both bistatic mode (common mid-points) for precise velocity constraints and monostatic mode (common-offset) for subsurface imaging. Reflections are derived from the active layer-permafrost boundary, organic layer-weathered soil boundary within the active layer, and frozen rock-fracture-filled ice boundary within the permafrost. The base of the imaged sorted circle possesses a convex-down shape in the central silty zone, which is typical for the pattern associated with convection-like soil motion within the active layer. The boundary between the central fine-silty domain and coarse-grained stone border is effectively identified in a radar amplitude contour at the assumed active layer depth, and is further examined in the frequency spectra of the near- and far-offset traces. The far-offset traces and the traces from the lower frequency components dominant on the far-offset traces would be associated with rapid absorption of higher frequency radiowave due to the voids in gravel-rich zone. The presented correlation strategies for analyzing very shallow, thin-layered GPR reflection data can potentially be applied to the various types of patterned ground, particularly for acquiring time-lapse imaging, when electric resistivity tomography is incorporated into the analysis.

Fluctuation Amplitudes of Magnetic-field Directional Turnings and Magnetic-velocity Alignment Structures in the Solar Wind

Abstract Magnetic-field directional turning (MFDT) and magnetic-velocity alignment structure (MVAS) are two typical types of structures in the solar wind. However, their fluctuation amplitudes in different turbulence states have not been studied before. Here, we present the amplitude distributions of MFDTs and MVASs in the plane, where is the correlation coefficient between magnetic-field and velocity fluctuations multiplied by the sign of the x component of the mean field in geocentric solar ecliptic coordinates, and σ r is normalized residual energy. Measurements from the WIND spacecraft in the slow solar wind during 2005–2009 are used for the analysis. The data are cut into intervals with duration of 6 minutes, and the intervals that are nearly incompressible are selected for analysis. We find that for the fluctuations with and −1 &lt; σ r &lt; −0.6, which are considered to be associated with MFDTs, the level contours of the pixel average amplitude of magnetic-field fluctuations in the plane show a horizontal-stripe feature with approximately km s−1 in Alfvén units. For the fluctuations with and −0.9 &lt; σ r &lt; −0.2, which are considered to be associated with MVASs, the level contours of the pixel average amplitude of velocity fluctuations show a vertical stripe feature with approximately km s−1. Consequently, the level contours of the pixel average amplitudes of Elsässer variables show “U” and “W” shapes, respectively. These results will help us to understand the nature of the fluctuations in the solar wind.

Nonlinear Flame Dynamics for Laminar Flame in a Co-flow Mixing Layer with Widely Varying Premixedness: Preferential Diffusion and Stoichiometry Effects

ABSTRACT Intrinsic oscillations arising due to thermo-diffusive mechanism have been studied numerically in the literature for laminar flames having Lewis number greater than unity. In the previous work, the Lewis numbers of fuel and oxidizer are assumed to be equal and the unburnt mixture to be in stoichiometric in proportion. Here, the study is extended to relax these assumptions. In the first part of the present work, the Lewis numbers of fuel and oxidizer are varied individually keeping the overall mixture stoichiometric. The simulations are run for laminar flames stabilized near to a cold burner in a co-flow mixing layer generated by a fuel rich stream and oxidizer rich stream. The premixedness of the unburnt mixture is varied using a premixedness parameter defined in the previous work. This parameter characterizes upstream mixture-fraction gradients such that it approaches unity for zero mixture-fraction gradient and zero when the mixture-fraction gradient is infinite. Thus, upon ignition, different flame structures like, planar premixed flame, triple flames and an edge flame can be observed, as this parameter is varied from zero to unity. Simulations are run to study large time behavior for various values in this range of premixedness. Intrinsic oscillations in the total reaction rate (integrated over the domain) are observed for a combination of values of Lewis numbers of fuel and oxidizer. These are presented as series of contour plots of amplitude of total reaction rate onto a 2D plane with Lewis number of fuel on x-axis and Lewis number of oxidizer on y-axis for various values of premixedness. It is found that the contours of constant amplitude are nearly linear for diffusion flame and partially premixed flames, thus validating the effective Lewis number definition hitherto defined for diffusion flames. Hence, this effective Lewis number can determine the onset of oscillations and also their magnitude. But for weakly curved triple flames, there is significant variation, where the constant amplitude lines are curved. Also, the amplitude of oscillations observed for weakly curved triple flames is much higher than that for other flames. Apart from intrinsic oscillations the shape and structure of triple flame is also studied. It is found that premixed flame branches of a triple flame are highly asymmetric about the trailing edge diffusion flame. The change in the location of triple point is also observed. In the second part of the work, the assumption of the overall stoichiometric ratio being unity is relaxed to understand the effect of the off-stoichiometric mixture on the shape and stability of flame. However, the Lewis numbers of the fuel and oxidizer are maintained to be equal. The maximum intensity of oscillations is observed at an equivalence ratio of 0.3 for partially premixed flames and at around unity for premixed flames.

Internal resonance analysis of a fluid-conveying tube resting on a nonlinear elastic foundation

This study used a fluid-conveying nonlinear beam and a nonlinear spring to simulate the vibration of a fluid-conveying tube placed on an elastic foundation. The centripetal force and tangential force of fluid acting on the tube wall were considered. In this paper, Hamilton’s principle is used to derive the equation for the nonlinear flow-structure coupled motion, where the method of multiple scales is used to derive the frequency response of each mode under the fixed point (steady state), and the amplitude of each mode is used to examine internal resonance. This study added (tuned mass dampers) TMDs of different masses, spring constants and damping coefficients at different locations in the system to observe the effect of the shock absorber in avoiding the internal resonance of the flow-structure coupled system and reducing the vibration of the system. Poincare map, maximum amplitude contour plots, and basin of attraction are used to analyze and compare the system to verify the correctness of our theory. The stability of the system is analyzed by changing the flow velocity of the fluid. The results show that under a certain combination of elastic foundation spring constants and flow speeds, the 1:3 internal resonance between the first and third modes of the main system will occur. In addition, the stability range of any case will increase significantly after TMD is added, indicating that TMD plays an important role.

Modeling of the near to far acoustic fields of an echolocating bottlenose dolphin and harbor porpoise.

Echolocation signals emitted by odontocetes can be roughly classified into three broad categories: broadband echolocation signals, narrowband high-frequency echolocation signals, and frequency modulated clicks. Previous measurements of broadband echolocation signal propagation in the bottlenose dolphin (Tursiops truncatus) did not find any evidence of focusing as the signals travel from the near-field to far-field. Finite element analysis (FEA) of high-resolution computed tomography scan data was used to examine signal propagation of broadband echolocation signals of dolphins and narrowband echolocation signals of porpoises. The FEA results were used to simulate the propagation of clicks from phonic lips, traveling through the forehead, and finally transmission into the water. Biosonar beam formation in the near-field and far-field, including the amplitude contours for the two species, was determined. The finite element model result for the simulated amplitude contour in the horizontal plane was consistent with prior direct measurement results for Tursiops, validating the model. Furthermore, the simulated far-field transmission beam patterns in both the vertical and horizontal planes were also qualitatively consistent with results measured from live animals. This study indicates that there is no evidence of convergence for either Tursiops or Phocoena as the sound propagates from the near-field to the far-field.

Masking Effects in the Perception of Multiple Simultaneous Talkers in Normal-Hearing and Cochlear Implant Listeners.

For normal-hearing (NH) listeners, monaural factors, such as voice pitch cues, may play an important role in the segregation of speech signals in multitalker environments. However, cochlear implant (CI) users experience difficulties in segregating speech signals in multitalker environments in part due to the coarse spectral resolution. The present study examined how the vocal characteristics of the target and masking talkers influence listeners’ ability to extract information from a target phrase in a multitalker environment. Speech recognition thresholds (SRTs) were measured with one, two, or four masker talkers for different combinations of target-masker vocal characteristics in 10 adult Mandarin-speaking NH listeners and 12 adult Mandarin-speaking CI users. The results showed that CI users performed significantly poorer than NH listeners in the presence of competing talkers. As the number of masker talkers increased, the mean SRTs significantly worsened from –22.0 dB to –5.2 dB for NH listeners but significantly improved from 5.9 dB to 2.8 dB for CI users. The results suggest that the flattened peaks and valleys with increased numbers of competing talkers may reduce NH listeners’ ability to use dips in the spectral and temporal envelopes that allow for “glimpses” of the target speech. However, the flattened temporal envelope of the resultant masker signals may be less disruptive to the amplitude contour of the target speech, which is important for Mandarin-speaking CI users’ lexical tone recognition. The amount of masking release was further estimated by comparing SRTs between the same-sex maskers and the different-sex maskers. There was a large amount of masking release in NH adults (12 dB) and a small but significant amount of masking release in CI adults (2 dB). These results suggest that adult CI users may significantly benefit from voice pitch differences between target and masker speech.

Duration and amplitude of tone production in children with cochlear implants

The purpose of the present study was two-fold: (1) to examine whether Mandarin-speaking children with CIs showed distinctive durational and amplitude features for the four lexical tones in their tone production; (2) to compare the duration and amplitude patterns of Mandarin lexical tones in monosyllables produced in citation form between CI children and age-matched normal-hearing (NH) children. The participants included 14 prelingually deafened Mandarin-speaking children with CIs and 14 NH children, all aged between 2.9 and 8.3 years old. Each participant produced five CV syllables (fa, fu, pi, xu, ke) in four tones through a tone drill activity. The vowel duration and rms amplitude values at nine equidistant time locations over the vowel duration were obtained. The results revealed that the CI children can produce distinctive duration and amplitude features for the four lexical tones. Their durational pattern and amplitude contours were highly similar to the NH children on tone 1, 2, and 4 but differed from the NH children on tone 3. In addition, NH children showed positively correlated amplitude contour and F0 contour but the CI children demonstrated inconsistent amplitude and F0 contours for tone 3. This finding suggested that the amplitude contour of a tone and the F0 contour of the same tone may not always be highly correlated.

Acoustic characteristics of belching in speech

“When such nonspeech sounds occur connected in speech they sometimes carry important social connotations (Pike, 1943: 39).” This sentiment is attested over and over again in linguistic literature that provides cases of nontraditional sounds (such as coughing, moans, cries) being co-opted into the continuous stream of speech within discourse (Ohala,1995; Ogden, 2013; Prelock and Hutchins, 2018; Pinto and Vigil, 2018). This reveals an unanswered problem: While many of these sounds have been able to be expressed by their phonetic parameters in paralinguistics (Trager, 1958; Poyatos, 1975), belching—as evident from a case study as being intentionally interjected into the speech stream with social connotations (Kidner, 2018)—has consistently eluded detailed description using acoustic parameters. Acoustic data were taken from this case study, and belching was distinguished in Praat (Boersma and Weenik, 2018) from modal speech by an increase in glottal pulses and jitter (&amp;gt;4.4%), an increase in shimmer (&amp;gt;15%), low pitch (≤300 Hz), and an irregular amplitude contour. These criteria for belch identification (while not exhaustive) allow us not just to classify belches phonetically within the corpus, but moves the process of acoustically defining otherwise difficult paralinguistic sounds forward.

Examination of Extraordinary Transmission of Waves Propagation through Gaps of Vertical Thin Barriers in Channels by A Hypersingular Boundary Element Method

The extraordinary transmission (ET) phenomenon is examined for waves propagating through gaps of vertical thin barriers in channels with a hypersingular boundary element method model on the linear potential theory, and an estimate formula based on small gap approximation for predicting the number of ET frequencies is proposed. Numerical computations are carried out to examine the influences of barrier number, barrier interval, gap size, gap position and barrier arrangement on extraordinary transmission and wave height in the channel. It shows that all of those factors evidently affect the extraordinary transmission frequencies. The contours of wave amplitude show that very high waves can be excited in the basins between barriers at the extraordinary transmission frequencies. Proper arrangement of barriers in a channel can avoid the occurrence of ET phenomenon and reduce wave height in the channel.

Dichotic integration of acoustic-phonetic information: Competition from extraneous formants increases the effect of second-formant attenuation on intelligibility.

Differences in ear of presentation and level do not prevent effective integration of concurrent speech cues such as formant frequencies. For example, presenting the higher formants of a consonant-vowel syllable in the opposite ear to the first formant protects them from upward spread of masking, allowing them to remain effective speech cues even after substantial attenuation. This study used three-formant (F1+F2+F3) analogues of natural sentences and extended the approach to include competitive conditions. Target formants were presented dichotically (F1+F3; F2), either alone or accompanied by an extraneous competitor for F2 (i.e., F1±F2C+F3; F2) that listeners must reject to optimize recognition. F2C was created by inverting the F2 frequency contour and using the F2 amplitude contour without attenuation. In experiment 1, F2C was always absent and intelligibility was unaffected until F2 attenuation exceeded 30 dB; F2 still provided useful information at 48-dB attenuation. In experiment 2, attenuating F2 by 24 dB caused considerable loss of intelligibility when F2C was present, but had no effect in its absence. Factors likely to contribute to this interaction include informational masking from F2C acting to swamp the acoustic-phonetic information carried by F2, and interaural inhibition from F2C acting to reduce the effective level of F2.

Free vibration predicted using forced oscillation in the lock-in region

The rationale of using the results from the transverse forced oscillation of a body in the lock-in region to predict the corresponding free vibration is provided based on the mathematical analysis and verified through the numerical results at Re = 106 obtained from the immersed boundary-lattice Boltzmann method. It is also shown through mathematical analysis that when the structural damping is fixed, if the body mass and stiffness vary together following a particular relationship, the free motion will remain the same. With this conclusion, the damping ratio is redefined using the motion frequency of the body instead of the commonly adopted natural frequency of the body. As a result, it is shown that when a cylinder is in periodic free motion, its motion will remain the same if the following two conditions are satisfied: (1) the combined mass-damping parameter remains unchanged and (2) the variations of body mass and stiffness follow a particular pattern. In this sense, the sinusoidal free motion will rely only on the combined mass-damping parameter, even at the low mass region. This is different from the previous result based on the conventionally defined mass-damping parameter. Motion amplitude and frequency contours are plotted against the damping and stiffness components based on the results of forced motion. From these, the sinusoidal free motion results can be predicted and their physics is discussed.

Cantonese Tone Identification in Three Temporal Cues in Quiet, Speech-Shaped Noise and Two-Talker Babble

Purpose: Cochlear implant processors deliver mostly temporal envelope information and limited fundamental frequency (F0) information to the users, which make pitch and lexical tone perception challenging for cochlear implantees. Different factors have been found to affect Mandarin tone perception in temporal cues but the most effective temporal cues for lexical tone identification across different backgrounds remained unclear because no study has comprehensively examined the effects and interactions of these factors, particularly, in languages that use both pitch heights and pitch shapes to differentiate lexical meanings. The present study compared identification of Cantonese tones in naturally produced stimuli, and in three temporal cues, namely the amplitude contour cue (TE50), the periodicity cue (TE500), and the temporal fine structure cue (TFS), in three different numbers of frequency bands (B04, B08, B16) in quiet and two types of noise (two male talker-babble and speech-shaped noise).Method: Naturally produced Cantonese tones and synthetic tones that combined different acoustic cues and different number of frequency bands were presented to 18 young native Cantonese speakers for tone identification in quiet and noise.Results: Among the three temporal cues, TFS was the most effective for Cantonese tone identification in quiet and noise, except for T4 (LF) identification. Its effect was even stronger when the tones were presented in 4 or 8 bands rather than 16 bands. Neither TE500 nor TE50 was effective for Cantonese tone identification in quiet or noise. In noise, most tones in TE500 and TE50 were misheard as T4 (LF), demonstrating errors in both tone shapes and tone heights. Types of noise had limited effect on tone identification.Conclusions: Findings on Mandarin tone perception in temporal cues may not be applicable to other tone languages with more complex tonal systems. TFS presented in four bands was the most effective temporal cue for Cantonese tone identification in quiet and noise. Temporal envelope cues were not effective for tone, tone shape or tone height identification in Cantonese. These findings have implications for future design of cochlear implants for tone speakers who use pitch heights or a combination of pitch heights and pitch shapes to differentiate meanings.

Stability analysis of heat transfer in shallow enclosure applied in glass-covered PV-T system

The flow state undergoes a series of transitions with varing inclination of the shallow enclosure constituted in the glass-covered PV-T system. Based on this fact, a three-dimensional unsteady numerical model has been established to investigate the flow mechanism. The surface radiation and PV operating characteristic were taken into consideration. The critical tilt angle from steady to unsteady state was determined under different heating conditions and initial conditions. With the decreasing of inclination, main features including spectrum amplitude, velocity distribution and temperature contours were specified in three flow states. Results show that in general, the critical tilt angle is a positive function of total input heat flux qt, the exception is the radiation uncoupled case of qt = 100 W/m2. When the reduction step size for inclination is fixed at only 1°, the derived critical tilt angle may be hysteretic. From the velocity contours, transverse roll in steady flow presents the dominant state. While during the transition process, the longitudinal flow is developed and superposed on the main flow step by step until the chaotic flow forms. In this state, continuous spectrum appears instead of several dominant frequencies observed in the periodic flow.