Variations Of Acoustic Characteristics Research Articles

Geographic variation of advertisement calls in the terrestrial frog Eleutherodactylus nitidus (Anura: Eleutherodactylidae) in southern Mexico

ABSTRACT Geographic variation in acoustic characteristics of anuran advertisement calls could be an important indicator of species divergence due to its importance for species recognition. In this study, we evaluated the hypotheses of morphological by-product, local adaptation, and genetic drift to explain the geographic variation of the calls of the frog Eleutherodactylus nitidus. We compared six acoustic variables using ANOVA and linear discriminant analyses, as well as inter- and intra-population and intra-individual variation estimates to understand E. nitidus call variation. Recorded calls were corrected for temperature and body size to rule out the influence of these factors on call variation. The advertisement call of E. nitidus is a short whistle with an oscillating amplitude modulation that forms pulses. In total, we analysed 1676 advertisement calls from 66 individuals. We find that call duration, call amplitude, dominant frequency, pulses per call and highest pulse differ between populations, and such differences were independent of body size and temperature variation, ruling out the morphological by-product and local adaptation hypotheses. Additionally, the linear discriminant analysis indicates that geographic call variation depends principally on call amplitude. We suggest that the geographic distance between populations of E. nitidus yields genetic differences that account for differences in advertisement calls.

Data Augmentation using virtual microphone array synthesis and multi-resolution feature extraction for isolated word dysarthric speech recognition

Dysarthria is a speech-motor disorder that affects the articulatory systems inhibiting their speech communication efforts. To handle their communication problems, a speech recognition-based augmentative and alternative communication aid is used as an attractive alternative. However, successful development of an automatic speech recognition (ASR)-based aid depends on the availability of sufficient speech data for training. Building an ASR system for dysarthric speakers is difficult due to limited amount of training data and large inter-and-intra speaker variabilities. Using normal speaker's speech data for data augmentation or adaptation for low intelligible dysarthric speakers would be extremely challenging due to huge variation in acoustic characteristics between these two category of speakers. In the current article, a two-level data augmentation is performed on dysarthric speech based on virtual linear microphone array-based synthesis followed by multi-resolution feature extraction. With the augmented speech data, an isolated word hybrid DNN-HMM-based ASR system is trained using UA speech corpus and Tamil dysarthric speech corpus developed by the authors. Performance of the ASR system shows a reduced WER of up to 32.79%, 35.75% for low and very low intelligible speakers with dysarthria compared to recent works on data augmentation reported for dysarthric speech recognition.

Characteristics of tiger moth (Erebidae: Arctiinae) anti-bat sounds can be predicted from tymbal morphology

BackgroundAcoustic signals are used by many animals to transmit information. Variation in the acoustic characteristics of these signals often covaries with morphology and can relay information about an individual’s fitness, sex, species, and/or other characteristics important for both mating and defense. Tiger moths (Lepidoptera: Erebidae: Arctiinae) use modified cuticular plates called “tymbal organs” to produce ultrasonic clicks which can aposematically signal their toxicity, mimic the signals of other species, or, in some cases, disrupt bat echolocation. The morphology of the tymbal organs and the sounds they produce vary greatly between species, but it is unclear how the variation in morphology gives rise to the variation in acoustic characteristics. This is the first study to determine how the morphological features of tymbals can predict the acoustic characteristics of the signals they produce.ResultsWe show that the number of striations on the tymbal surface (historically known as “microtymbals”) and, to a lesser extent, the ratio of the projected surface area of the tymbal to that of the thorax have a strong, positive correlation with the number of clicks a moth produces per unit time. We also found that some clades have significantly different regression coefficients, and thus the relationship between microtymbals and click rate is also dependent on the shared ancestry of different species.ConclusionsOur predictive model allows the click rates of moths to be estimated using preserved material (e.g., from museums) in cases where live specimens are unavailable. This has the potential to greatly accelerate our understanding of the distribution of sound production and acoustic anti-bat strategies employed by tiger moths. Such knowledge will generate new insights into the evolutionary history of tiger moth anti-predator defenses on a global scale.

Gender Variation in Acoustic Characteristics of Southern Pa-O Lexical Tones

Southern Pa-O (S. Pa-O) is a Karenic language of the Tibeto-Burman subgroup of the Sino-Tibetan language family. In Thailand, there is a large S. Pa-O community around Rama II Road. This study aims to investigate the gender variation in acoustic characteristics of S. Pa-O lexical tones. F0 in Hertz based on the biological difference of larynx vibrating rate was converted into semitones to normalize cross-speaker differences. Then, semitone and real time values of 6 lexical tones (4 non-checked tones and 2 checked tones) were used to generate 2nd degree polynomial trendlines to show F0 contours and shapes.

Fault Detection of Linear Guide Preload of a Positioning Stage with Vibration–Acoustic Analysis

The vibration analysis method has been widely used to detect faults in the components of a machine. For a linear positioning stage, its vibration characteristics are closely related to and affected by the preload of linear guides. To clarify the meaning of the vibration signals coming out from an abnormal machine, in this study we aimed to investigate the influence of a faulty linear guide on the vibration and acoustic characteristics of a positioning stage through experimental and finite element modeling approaches. Experimental measurements indicate that stages equipped with abnormal or damaged linear guides indeed exhibit different vibration behavior compared to stages with intact guides. According to finite element analysis, the variation in vibration characteristics can be attributed to the changes in the structural stiffness of linear guides because of rolling ball defects. This phenomenon was also found in the acoustic characteristics measured for stages under various preloaded conditions, providing further correlations between the variations in acoustic characteristics and changes in structural stiffness. The present results clearly show that faulty conditions of linear guides can be effectively detected by means of monitoring the vibration and acoustic characteristics of the stage.

Investigating within and between talker variability in the optical characteristics of American English vowels.

Previous research investigating vowel production provides evidence of substantial within and cross-talker variation in acoustic characteristics. The current study is designed to investigate whether similar within and cross-talker variation exists in the optical characteristics of American English vowels. Additionally, potential shared acoustic-optical variation across tokens will also be examined. Measures taken from three-dimensional motion data for a set of 13 markers positioned around the lips, cheeks, and chin sampled at 100 frames/s with millimeter spatial resolution along with simultaneous video (50 frames/s) and audio for each of ten repetitions of 11 vowels spoken by multiple talkers will be reported. Preliminary analysis of motion and acoustic data from12 repetitions of 11 vowels spoken by one male talker provides evidence of substantial within vowel variation in both vertical and horizontal lip separations measured at the midpoint of the vowel as determined by analysis of the acoustic signal. Correlations were observed between horizontal lip separation and second formant frequency (r = 0.48) and third formant frequency (r = 0.66) at the vowel midpoint. No correlations were obtained with vertical lip separation measure. Results will be discussed in terms of potential implications for talker intelligibility in visual only presentation conditions.

An underwater sensor allocation scheme for a range dependent environment

A series of assumptions is typically made when designing a field of passive underwater sensors. One of the more glaring is range independence throughout an operational area. It is unlikely that a large water space will have uniform acoustic characteristics throughout, i.e., the performance of a sensor will vary based upon its physical location. In an area clearance scenario, where there is no apparent target for an adversary to gravitate towards, such as a ship or a port, it is difficult to determine where the field designer should allocate sensors so that their deployment locations can be planned efficiently. To intelligently allocate sensors, a field designer could first divide an area into sectors of relatively uniform acoustics, based upon variations in acoustic characteristics throughout the area. A prediction of how often a threat submarine will visit each sector can then be made in order to increase the field’s detection capabilities. In this work, an area of interest is divided into sectors of varying geographic size and acoustic characteristics and the probability of visitation to each sector by a threat submarine is determined by solving a minimax matrix game . The Game Theory Field Design (GTFD) model is proposed, which allocates sensors to sectors of relatively uniform acoustics according to the visitation probabilities of an adversary, against adversaries of varying intelligence. In a comparison with two models that do not consider these visitation probabilities and only examine either acoustic characteristics or the size of the sectors, GTFD is shown to offer a significant improvement in terms of overall field detection capability against intelligent adversaries .

Does bill size polymorphism affect courtship song characteristics in the African finch Pyrenestes ostrinus?

Vocal characteristics of bill morphs of the African finch Pyrenestes ostrinus were investigated to see whether there were differences between the morphs that could potentially lead to assortative mating. Morphological differences between bill morphs are of a scale that could change resonance characteristics, with as a physical consequence, a change in acoustic characteristics. Song and variation in acoustic characteristics are very likely to be an important factor in mate choice. We analysed recordings of large and small-billed birds, and measured 11 acoustic characteristics focusing on frequency use and possibly correlated temporal features. In addition, we investigated in more detail the energy distribution within the frequency limits. We found no differences between bill morphs in acoustic characteristics of courtship song. Our findings contrast with other empirical studies which show an impact of the suprasyringeal vocal tract on song output. One possible explanation could be that the morphological changes affect resonance characteristics in multiple ways which do not operate in concert. Beside proximate aspects, we discuss the role of song and the bill polymorphism in the context of sympatric speciation.

Does bill size polymorphism affect courtship song characteristics in the African finch Pyrenestes ostrinus?

Vocal characteristics of bill morphs of the African finch Pyrenestes ostrinus were investigated to see whether there were differences between the morphs that could potentially lead to assortative mating. Morphological differences between bill morphs are of a scale that could change resonance characteristics, with as a physical consequence, a change in acoustic characteristics. Song and variation in acoustic characteristics are very likely to be an important factor in mate choice. We analysed recordings of large and small-billed birds, and measured 11 acoustic characteristics focusing on frequency use and possibly correlated temporal features. In addition, we investigated in more detail the energy distribution within the frequency limits. We found no differences between bill morphs in acoustic characteristics of courtship song. Our findings contrast with other empirical studies which show an impact of the suprasyringeal vocal tract on song output. One possible explanation could be that the morphological changes affect resonance characteristics in multiple ways which do not operate in concert. Beside proximate aspects, we discuss the role of song and the bill polymorphism in the context of sympatric speciation.