基于局部轮廓特征的无人机头部检测跟踪算法

针对无人机的结构特点,提出了一种基于目标轮廓提取、轮廓自动分段、头部定位以及头部模板匹配四个模块的目标头部检测跟踪算法.首先对第一帧图像提取目标轮廓,并通过计算轮廓点的变化率,对轮廓进行自动分段,得到目标的4个局部轮廓点列,进而根据头部轮廓点列的特点,完成头部轮廓筛选,然后利用基于目标中轴的二次曲线拟合,实现头部顶点的...     

基于不相似度评价的水下声目标分类与听觉特征辨识

本文旨在探索人类被试对水下声目标的感知分类及在该过程中所利用的听觉特征.首先设计了成对比较实验.然后利用CLASCAL算法对实验获得的不相似度评分进行建模,获得感知空间,并分析了3个公共维度、特异性和3个被试潜类各自的特性及其在目标感知分类中所起的作用.最后,基于Gammatone听觉滤波器组对声样本进行分析,发现了能够有效描述3个公共维度以及节拍特性的听觉特征,并利用它们构造决策树对新样本实现了分类,从而为实际中如何应用这些特征提供了指导.     

水中目标回波亮点统计特征研究

礁石和海洋动物引起的混响是主动声纳最严重的干扰, 如何区分礁石、鱼群和水中目标一直是制约主动声纳识别技术的难点问题. 针对礁石与目标回波难以区分的问题, 从特征识别的应用角度, 研究水中复杂目标全方位回波亮点特征的有效表征和应用方式, 基于目标回波亮点模型, 提出拷贝相关器输出的目标散射函数估计方法, 给出对目标回波亮点相对关系进行定量分析的目标回波特征统计表征方式, 并基于湖上实验提取了物理机理明确的目标回波亮点统计特征, 使得目标时间-角度谱中所蕴含的目标特征信息能够很直接地转化为主动声纳易于应用的目标特征. 关键词： 水中目标 回波亮点 统计特征     

一种鲁棒的目标跟踪方法

针对传统特征光流场跟踪方法中由于误差积累和错误匹配而导致的特征点丢失问题,基于一种新的Harris-SIFT特征点表示方法,提出基于预测帧与关键帧的算法框架,实现了光流场运动估计与局部特征识别相结合的目标跟踪方法.预测帧利用塔式分解和递归算法计算特征点的光流场运动矢量,使用运动矢量直方图获取目标的运动矢量,并剔除误匹配点;当特征点数量小于5个时,关键帧使用Harris-SIFT特征点进行局部特征匹配,利用仿射模型对目标精确定位及姿态修正.实验结果表明,本方法对视频序列中的纹理特征目标跟踪的鲁棒性较好,在背景复杂、目标遮挡或暂时丢失情况下,仍可以继续完成目标的可靠跟踪.     

一种鲁棒的目标跟踪方法

针对传统特征光流场跟踪方法中由于误差积累和错误匹配而导致的特征点丢失问题,基于一种新的Harris-SIFT特征点表示方法,提出基于预测帧与关键帧的算法框架,实现了光流场运动估计与局部特征识别相结合的目标跟踪方法.预测帧利用塔式分解和递归算法计算特征点的光流场运动矢量,使用运动矢量直方图获取目标的运动矢量,并剔除误匹配点;当特征点数量小于5个时,关键帧使用Harris-SIFT特征点进行局部特征匹配,利用仿射模型对目标精确定位及姿态修正.实验结果表明,本方法对视频序列中的纹理特征目标跟踪的鲁棒性较好,在背景复杂、目标遮挡或暂时丢失情况下,仍可以继续完成目标的可靠跟踪.     

基于分段轮廓平滑的目标识别

提出了一种基于分段轮廓平滑的目标识别算法.首先通过曲率将轮廓划分为特征区域和非特征区域;然后在不同区域内分别采用不同方差的高斯函数进行轮廓平滑;最后采用基于仿射不变矩的目标识别算法对平滑后的目标轮廓进行识别.结果表明,该算法不仅取得了更好的轮廓平滑效果,而且在强噪音条件下能够显著提高识别准确率.     

一种基于纹理特征的红外成像目标跟踪方法

提出了一种基于LBP（Local Binary Pattern)纹理特征的红外成像目标跟踪方法,将LBP纹理特征集成到了核跟踪方法中.根据目标各区域对背景的区分能力不同,提出了目标各区域置信度的评价方法,用基于区域置信度及空间距离核加权的LBP特征概率密度函数,构造了目标及候选目标的特征模型.通过相似性度量,利用均值漂移方法实现了基于纹理特征的红外成像目标跟踪.实验结果验证了该算法在红外成像目标跟踪中较基于灰度的均值漂移跟踪算法更为鲁棒.     

基于分段轮廓平滑的目标识别

提出了一种基于分段轮廓平滑的目标识别算法.首先通过曲率将轮廓划分为特征区域和非特征区域|然后在不同区域内分别采用不同方差的高斯函数进行轮廓平滑;最后采用基于仿射不变矩的目标识别算法对平滑后的目标轮廓进行识别.结果表明,该算法不仅取得了更好的轮廓平滑效果,而且在强噪音条件下能够显著提高识别准确率.     

一种基于特征点间线段倾角的姿态测量方法

基于目标特征点间线段倾角信息,提出了一种适合于目标远距离成像和相机内参未知条件下解算目标姿态的目标3维姿态测量方法.采用仿真图像对该方法的正确性进行了验证.实验结果:姿态测量误差绝对值均值小于0.6°,且目标成像尺寸为350pixel时,姿态测量误差绝对值小于0.5°.实验表明该算法具有较高解算准确度和较强的收敛性.     

特征增强SSD算法及其在遥感目标检测中的应用

为了提高对复杂场景下多尺度遥感目标的检测精度,提出了基于多尺度单发射击检测(SSD)的特征增强目标检测算法.首先对SSD的金字塔特征层中的浅层网络设计浅层特征增强模块,以提高浅层网络对小目标物体的特征提取能力;然后设计深层特征融合模块,替换SSD金字塔特征层中的深层网络,提高深层网络的特征提取能力;最后将提取的图像特征与不同纵横比的候选框进行匹配以执行不同尺度遥感图像目标检测与定位.在光学遥感图像数据集上的实验结果表明,该算法能够适应不同背景下的遥感目标检测,有效地提高了复杂场景下的遥感目标的检测精度.此外,在拓展实验中,文中算法对图像中的模糊目标的检测效果也优于SSD.     

Acoustic characteristics of Mandarin esophageal speech

The present study attempted to investigate the acoustic characteristics of Mandarin laryngeal and esophageal speech. Eight normal laryngeal and seven esophageal speakers participated in the acoustic experiments. Results from acoustic analyses of syllables /ma/and /ba/ indicated that, F0, intensity, and signal-to-noise ratio of laryngeal speech were significantly higher than those of esophageal speech. However, opposite results were found for vowel duration, jitter, and shimmer. Mean F0, intensity, and word per minute in reading were greater but number of pauses was smaller in laryngeal speech than those in esophageal speech. Similar patterns of F0 contours and vowel duration as a function of tone were found between laryngeal and esophageal speakers. Long-time spectra analysis indicated that higher first and second formant frequencies were associated with esophageal speech than that with normal laryngeal speech.     

Beneficial acoustic speech cues for cochlear implant users with residual acoustic hearing

This study investigated which acoustic cues within the speech signal are responsible for bimodal speech perception benefit. Seven cochlear implant (CI) users with usable residual hearing at low frequencies in the non-implanted ear participated. Sentence tests were performed in near-quiet (some noise on the CI side to reduce scores from ceiling) and in a modulated noise background, with the implant alone and with the addition, in the hearing ear, of one of four types of acoustic signals derived from the same sentences: (1) a complex tone modulated by the fundamental frequency (F0) and amplitude envelope contours; (2) a pure tone modulated by the F0 and amplitude contours; (3) a noise-vocoded signal; (4) unprocessed speech. The modulated tones provided F0 information without spectral shape information, whilst the vocoded signal presented spectral shape information without F0 information. For the group as a whole, only the unprocessed speech condition provided significant benefit over implant-alone scores, in both near-quiet and noise. This suggests that, on average, F0 or spectral cues in isolation provided limited benefit for these subjects in the tested listening conditions, and that the significant benefit observed in the full-signal condition was derived from implantees' use of a combination of these cues.     

Use of intonation contours for speech recognition in noise by cochlear implant recipients

The corruption of intonation contours has detrimental effects on sentence-based speech recognition in normal-hearing listeners Binns and Culling [(2007). J. Acoust. Soc. Am. 122, 1765-1776]. This paper examines whether this finding also applies to cochlear implant (CI) recipients. The subjects' F0-discrimination and speech perception in the presence of noise were measured, using sentences with regular and inverted F0-contours. The results revealed that speech recognition for regular contours was significantly better than for inverted contours. This difference was related to the subjects' F0-discrimination providing further evidence that the perception of intonation patterns is important for the CI-mediated speech recognition in noise.     

A Comparative Study of Acoustic Voice Measurements by Means of Dr. Speech and Computerized Speech Lab

In this study, the calculations and results of acoustic voice analysis as calculated by two different analysis systems (Doctor Speech (DRS), Tiger Electronics, Neu-Anspach, Germany, and Computerized Speech Lab (CSL), Kay Elemetrics Corporation, Lincoln Park, NJ) are compared. A group of 120 normal voices was selected for analysis of the objective parameters: fundamental frequency (F(0)), variation of F(0) (F(0)SD), jitter, shimmer, and harmonics-to-noise ratio (HNR). The subject group was a random selection of normal voices of adults. The aim of this comparison was to find determined differences and similarities in data measurements between both systems to make data transfer possible. A significant correlation was found for F(0), HNR, and shimmer relative. The correlation for jitter (relative and absolute) and F(0)SD was weak. DRS and CSL are not comparable in absolute figures, but their judgment against normative data is identical. Further research is necessary to explore the affect on pathological voices or child voices.     

Constrained tone transformation technique for separation and combination of Mandarin tone and intonation

This paper addresses a classical but important problem: The coupling of lexical tones and sentence intonation in tonal languages, such as Chinese, focusing particularly on voice fundamental frequency (F1) contours of speech. It is important because it forms the basis of speech synthesis technology and prosody analysis. We provide a solution to the problem with a constrained tone transformation technique based on structural modeling of the F1 contours. This consists of transforming target values in pairs from norms to variants. These targets are intended to sparsely specify the prosodic contributions to the F1 contours, while the alignment of target pairs between norms and variants is based on underlying lexical tone structures. When the norms take the citation forms of lexical tones, the technique makes it possible to separate sentence intonation from observed F0 contours. When the norms take normative F0 contours, it is possible to measure intonation variations from the norms to the variants, both having identical lexical tone structures. This paper explains the underlying scientific and linguistic principles and presents an algorithm that was implemented on computers. The method's capability of separating and combining tone and intonation is evaluated through analysis and re-synthesis of several hundred observed F0 contours.     

Sex differences in the acoustic structure of vowel-like grunt vocalizations in baboons and their perceptual discrimination by baboon listeners

This study quantifies sex differences in the acoustic structure of vowel-like grunt vocalizations in baboons (Papio spp.) and tests the basic perceptual discriminability of these differences to baboon listeners. Acoustic analyses were performed on 1028 grunts recorded from 27 adult baboons (11 males and 16 females) in southern Africa, focusing specifically on the fundamental frequency (F0) and formant frequencies. The mean F0 and the mean frequencies of the first three formants were all significantly lower in males than they were in females, more dramatically so for F0. Experiments using standard psychophysical procedures subsequently tested the discriminability of adult male and adult female grunts. After learning to discriminate the grunt of one male from that of one female, five baboon subjects subsequently generalized this discrimination both to new call tokens from the same individuals and to grunts from novel males and females. These results are discussed in the context of both the possible vocal anatomical basis for sex differences in call structure and the potential perceptual mechanisms involved in their processing by listeners, particularly as these relate to analogous issues in human speech production and perception.     

The relative phonetic contributions of a cochlear implant and residual acoustic hearing to bimodal speech perception

The addition of low-passed (LP) speech or even a tone following the fundamental frequency (F0) of speech has been shown to benefit speech recognition for cochlear implant (CI) users with residual acoustic hearing. The mechanisms underlying this benefit are still unclear. In this study, eight bimodal subjects (CI users with acoustic hearing in the non-implanted ear) and eight simulated bimodal subjects (using vocoded and LP speech) were tested on vowel and consonant recognition to determine the relative contributions of acoustic and phonetic cues, including F0, to the bimodal benefit. Several listening conditions were tested (CI/Vocoder, LP, T(F0-env), CI/Vocoder + LP, CI/Vocoder + T(F0-env)). Compared with CI/Vocoder performance, LP significantly enhanced both consonant and vowel perception, whereas a tone following the F0 contour of target speech and modulated with an amplitude envelope of the maximum frequency of the F0 contour (T(F0-env)) enhanced only consonant perception. Information transfer analysis revealed a dual mechanism in the bimodal benefit: The tone representing F0 provided voicing and manner information, whereas LP provided additional manner, place, and vowel formant information. The data in actual bimodal subjects also showed that the degree of the bimodal benefit depended on the cutoff and slope of residual acoustic hearing.     

The role of fundamental frequency contours in the perception of speech against interfering speech

Four experiments investigated the effect of the fundamental frequency (F0) contour on speech intelligibility against interfering sounds. Speech reception thresholds (SRTs) were measured for sentences with different manipulations of their F0 contours. These manipulations involved either reductions in F0 variation, or complete inversion of the F0 contour. Against speech-shaped noise, a flattened F0 contour had no significant impact on SRTs compared to a normal F0 contour; the mean SRT for the flattened contour was only 0.4 dB higher. The mean SRT for the inverted contour, however, was 1.3 dB higher than for the normal F0 contour. When the sentences were played against a single-talker interferer, the overall effect was greater, with a 2.0 dB difference between normal and flattened conditions, and 3.8 dB between normal and inverted. There was no effect of altering the F0 contour of the interferer, indicating that any abnormality of the F0 contour serves to reduce intelligibility of the target speech, but does not alter the masking produced by interfering speech. Low-pass filtering the F0 contour increased SRTs; elimination of frequencies between 2 and 4 Hz had the greatest effect. Filtering sentences with inverted contours did not have a significant effect on SRTs.     

Pitch (F0) and formant profiles of human vowels and vowel-like baboon grunts: the role of vocalizer body size and voice-acoustic allometry

Key voice features--fundamental frequency (F0) and formant frequencies--can vary extensively between individuals. Much of the variation can be traced to differences in the size of the larynx and vocal-tract cavities, but whether these differences in turn simply reflect differences in speaker body size (i.e., neutral vocal allometry) remains unclear. Quantitative analyses were therefore undertaken to test the relationship between speaker body size and voice F0 and formant frequencies for human vowels. To test the taxonomic generality of the relationships, the same analyses were conducted on the vowel-like grunts of baboons, whose phylogenetic proximity to humans and similar vocal production biology and voice acoustic patterns recommend them for such comparative research. For adults of both species, males were larger than females and had lower mean voice F0 and formant frequencies. However, beyond this, F0 variation did not track body-size variation between the sexes in either species, nor within sexes in humans. In humans, formant variation correlated significantly with speaker height but only in males and not in females. Implications for general vocal allometry are discussed as are implications for speech origins theories, and challenges to them, related to laryngeal position and vocal tract length.