This thesis deals with the theoretical and practical part of the phenomenon of acoustic emission. The thesis examined the theoretical foundations of this phenomenon and also described the equipment that was used in the laboratory of VUT in Brno to perform measurements. Then measurements and their analysis were described. Several possible errors that occurred during the work on the thesis were also described. Error description is the basis for error-free laboratory testing and for improving the quality of laboratory testing.

This Master’s thesis is concerned with project and construction of several versions of mounting device for verification of acoustic emission sensors parameters, selection of optimal solution and its testing. In addition is described the measurement procedure, that allows detailed analysis and evaluation of the data focused on comparing of parameters of acoustic emission sensors.

The clinical value of oto-acoustic emissions (OAEs) for the identification of the integrity of outer hair cell function has been proven numerous times in research studies, and OAEs are commonly included in the audiological test battery used by audiologists. The technological advances in this field, however, require continuous research to determine the value of new equipment. The main objective of this study was to determine the test-retest reliability of distortion product oto-acoustic emissions (DPOAEs) and transient evoked oto-acoustic emissions (TEOAEs). The subjects were female adults between 18 and 25 years of age, and 30 ears were used for this study. All participants had normal middle-ear function, normal hearing sensitivity (pure tone thresholds) and present OAEs. DPOAEs and TEOAEs were performed at specific time intervals to determine the test-retest reliability, and an OAE-gram was generated by combining DPOAE and TEOAE test results. These measures were performed as an initial measure (M1), after five minutes (M2), after an hour (M3), after a week (M4) and after a month (M5). The test-retest reliability was calculated by analysing the statistics quantitatively. Results were analysed to determine the variance between each participant individually at different time intervals, and also to determine the variance of the group as a whole at different time intervals. Through this analysis high test-retest reliability between the different tests was proven. Inferential statistical Analysis of Variance (ANOVA) and Intraclass Correlation Coefficient (ICC) proved that the test-retest reliability of DPOAEs, TEOAEs and the OAE-gram (generated through a combination of the DPOAE and TEOAE results) was consistent throughout all periods of testing. The highest correlation existed between immediate re-measurements, while the largest difference was observed between M1 and M3. High test-retest reliability for all tests conducted at different time intervals from original measures were confirmed. Recommendations that arose from this study are further research in the normal hearing population for better generalization, research into specific variables between subjects, research with longer time between different tests, as well as the test-retest reliability in pathologic populations. / Dissertation (MCommunication Pathology)--University of Pretoria, 2017. / Speech-Language Pathology and Audiology / MCommunication Pathology / Unrestricted

A model that can accurately predict speech recognition for cochlear implant (CI) listeners is essential for the optimal fitting of cochlear implants. By implementing a CI acoustic model that mimics CI speech processing, the challenge of predicting speech perception in cochlear implants can be simplified. As a first step in predicting the recognition of speech processed through an acoustic model, vowel perception in severe speech-shaped noise was investigated in the current study. The aim was to determine the acoustic cues that listeners use to recognize vowels in severe noise and make suggestions regarding a vowel perception predictor. It is known that formants play an important role in quiet, while in severe noise the role of formants is still unknown. The relative importance of F1 and F2 is also of interest, since the masking of noise is not always evenly distributed over the vowel spectrum. The problem was addressed by synthesizing vowels consisting of either detailed spectral shape or formant information. F1 and F2 were also suppressed to examine the effect in severe noise. The synthetic stimuli were presented to listeners in quiet and signal-to-noise ratios of 0 dB, -5 dB and -10 dB. Results showed that in severe noise, vowels synthesized according to the whole-spectrum were recognized significantly better than vowels containing only formants. Multidimensional scaling and FITA analysis indicated that formants were still perceived and extracted by the human auditory system in severe noise, especially when the vowel spectrum consisted of the whole spectral shape. Although F1 and F2 vary in importance in listening conditions of quiet and less noisy conditions, the role of the two cues appears to be similar in severe noise. It was suggested that not only the availability formants, but also details of the vowel spectral shape can help to predict vowel recognition in severe noise to a certain degree. / Dissertation (MEng)--University of Pretoria, 2010. / Electrical, Electronic and Computer Engineering / unrestricted

Breast cancer is the No.1 prevalent new cancer in female cancer now. Compared to mastectomy (removing the entire breast), breast-conserving surgery (only removing cancerous tissue), has become the preferred treatment for its better cosmetic outcome and patient healthcare. However, it is challenging for surgeons to accurately locate the tumor and completely remove it during the surgery. Consequently, it leads to prolonged surgical time and inadequate tumor margins, which requires a second operation. Currently, the reoperation rate in the U.S. is as high as 25%. This is due to the lack of intraoperative tumor margin assessment and accurate breast tumor localization tools inside the operating room (OR), making current lumpectomy far from precise. My thesis work aims to achieve precision lumpectomy through development of photo- and thermo-acoustic imaging and sensing techniques. To fulfill the first unmet need of high-speed intraoperative assessment of breast tumor margins, we developed a compact multimodal ultrasound and bond-selective photoacoustic imaging system to image the entire excised tissue in just 10 minutes. The system was validated at hospitals with fresh lumpectomy specimens from 66 patients, and it achieved a sensitivity of 85.5% and specificity of 90%, showing its potential for high-speed and accurate intraoperative assessment of breast tumor margins. Next, we addressed the second unmet need of fast and accurate breast tumor localization in the OR through development of a fiber optoacoustic guide (FOG). It resembles the current metal guide wire but broadcasts MHz ultrasound omnidirectional via photoacoustic effect and can achieve sub-mm tumor localization. With an augmented reality system, the obtained tumor location was projected as an intuitive visual guidance to minimize the interference to surgical workflow and achieve optimal surgical planning. A surgeon successfully deployed the FOG to excise a “pseudo tumor” in a female human cadaver. Lastly, to improve the patient flow and logistics in clinics with a wireless breast tumor localization tool, we developed a resonant ring antenna that converts microwave into ultrasound to realize a wireless acoustic beacon. As a proof-of-concept, the ring antenna demonstrated over 3 orders of improvement in conversion efficiency than a common contrast agent for thermo-acoustic imaging. / 2021-08-30T00:00:00Z

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21754号 / 工博第4571号 / 新制||工||1712(附属図書館) / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 西脇 眞二, 教授 北村 隆行, 教授 小森 雅晴 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

The properties of acoustic kinetic energy density and total energy density of sound fields in lightly damped enclosures have been explored thoroughly in the literature. Their increased spatial uniformity makes them more favorable measurement quantities for various applications than acoustic potential energy density (or squared pressure), which is most often used. In this dissertation, a new acoustic energy quantity, the generalized acoustic energy density (GED), will be introduced. It is defined by introducing weighting factors, α and 1 − α, in the formulation of total acoustic energy density. With the additional degree of freedom, the GED can conform to the traditional acoustic energy density quantities, or be optimized for different applications. The properties and applications of the GED are explored in this dissertation. For enclosed sound fields, it was found that GED with α = 1/4 is spatially more uniform than the acoustic potential energy density, acoustic kinetic energy density, and the total acoustic energy density, which makes it a more favorable measurement quantity than those traditional acoustic energy density quantities for many indoor measurement applications. For some other applications, such as active noise control in diffuse field, different values of α may be considered superior. The numerical verifications in this research are mainly based on a hybrid modal expansion developed for this work, which combines the free field Green's function and a modal expansion. The enclosed sound field is separated into the direct field and reverberant field, which have been treated together in traditional modal analysis. Studies on a point source in rectangular enclosures show that the hybrid modal expansion converges notably faster than the traditional modal expansions, especially in the region near the source, and introduces much smaller errors with a limited number of modes. The hybrid modal expansion can be easily applied to complex sound sources if the free field responses of the sources are known. Damped boundaries are also considered in this dissertation, and a set of modified modal functions is introduced, which is shown to be suitable for many damped boundary conditions.

No description available.

Nightjars are a group of nocturnal and aerial insectivorous birds that have experienced long-term decline likely driven primarily by habitat loss and declines in prey populations. Eastern Whip-poor-will (Antrostomus vociferus) and Chuck-will’s-widow (Antrostomus carolinensis), two nightjar species native to Illinois, declined 69% and 58% since 1966, respectively. Although previous survey efforts have documented presence of Chuck-will’s-widow and Whip-poor-will, their current distribution in the state is not well known. Using Autonomous Recording Units (ARUs) deployed in a uniform, systematic grid, I surveyed 142 locations from May – July 2022 on public and private lands across the southern eleven counties of Illinois to assess Whip-poor-will and Chuck-will’s-widow distribution and estimate species occupancy. I estimated species relationships with proportion of landcover types, forest patch configuration, and proximity to other landcover types. Additionally, I quantified disturbances from the past 15 years to estimate species relationships to the severity and duration of disturbances. I deployed ARUs for 710 survey days collecting 170,400 minutes or 3,000 hours of recordings. Acoustic bird call identification software, BirdNet, was highly accurate at detecting focal species and greatly reduced the time spent manually reviewing acoustic data. BirdNet identified 43,922 calls of Whip-poor-will and 31,447 calls of Chuck-will’s-widow. I detected Whip-poor-will on 78 surveys with 100% accuracy and Chuck-will’s-widow on 75 surveys with 76% accuracy. Whip-poor-will were positively associated with forest patches with large core areas that neighbored pastures. Additionally, Whip-poor-will were likely to occupy landscapes that had experienced low to moderate disturbance within the previous 15 years. Covariates used to model Chuck-will’s-widow occupancy explained little variation in detection or occupancy and there were no significant relationships with any covariate. However, examining non-significant trends suggest similar relationships as Whip-poor-will in the area. Results highlight the efficiency of passive acoustic monitoring for these birds and the need for further investigation into Chuck-will’s-widow species-environmental relationships. In southern Illinois, Chuck-will’s-widow populations appears to be consistent with previous estimates from the 1990s while Whip-poor-will follow the broader trend of decline.

Background: Technological advancements in speech acoustic analysis have led to the development of spectral/cepstral analyses due to questions regarding the validity of traditional time-based measures (i.e., Jitter, Shimmer, and Harmonics-to-Noise-Ratio) in objectifying perturbations in dysphonic voices. Aim: This study investigated the validity of time-based measures in discriminating those with Friedreich’s ataxia (FA) from normal voiced (NV) peers when compared to cepstral-spectral measures. Method: A total of 120 sustained vowel phonations from an existing database of 40 participants (20 FA; 20 NV) of the vowels /ɑ/, /i/, and /o/ were analyzed to determine which set of variables (i.e., time-based vs. cepstral-spectral) better predicted group membership. Four variables of time-based measures (Jitter Local %, Jitter RAP, Shimmer Local %, Shimmer APQ11, and HNR) were analyzed via the freeware program PRAAT and compared to four cepstral-spectral measures (Cepstral Peak Prominence, Cepstral Peak Prominence Standard Deviation, Low/High Ratio Standard Deviation, and the Cepstral/ Spectral Index of Dysphonia) extracted from the Analysis of Dysphonia in Speech and Voice (ADSV) software program. Results: Findings from a discriminant analysis showed sensitivity and specificity results to be better for ADSV measures; 100% of those in the FA group were classified correctly (sensitivity), and 95% of members in the NV group were correctly identified (specificity) as compared to PRAAT (70% sensitivity and 85% specificity). Conclusions: Cepstral-spectral measures are much more accurate in discriminating between those with FA and NV peers as compared to time-based estimates.