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1
Lipembe, Pembe Peter Agustini. "Exploring the micro-social dynamics of intergenerational language transmission :a critical analysis of parents's attitudes and language use patterns among Ndamba speakers in Tanzania." Thesis, University of the Western Cape, 2010. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_5270_1297836275.
Full textAbstract:
The study has several implications
for general theoretical traditions it highlights the point that ambivalent attitudes and incomplete language use are responsible for gradual language decline. Previous studies while acknowledging the role of community based, intuitive conditions on language maintenance and shift, did not show how the process occurred. For policy the study aims toward sensitizing policy makers and raise their awareness about the dire situation in which minority languages currently are in. This would ensure that politicians, bureaucrats, and other state authorities could implement policy decisions that guarantee protection of minority languages and enhance their vitality. One policy strategy that could ensure revitalization of minority languages would be to include them in the school curriculum as supplementary approach to the effort of the home and the community, as McCarty (2002, quoted in Recento, 2006) observes that schools
[&hellip
] can be constructed as a place where children can be free to be indigenous in the indigenous language &ndash
in all of its multiple and everchanging meanings and forms.
2
Sturtzer, Eric. "Modélisation en vue de l'intégration d'un système audio de micro puissance comprenant un haut-parleur MEMS et son amplificateur." Phd thesis, INSA de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-00940463.
Full textAbstract:
Ce manuscrit de thèse propose l'optimisation de l'ensemble de la chaîne de reproduction sonore dans un système embarqué. Le premier axe de recherche introduit les notions générales concernant les systèmes audio embarqués nécessaires à la bonne compréhension du contexte de la recherche. Le principe de conversion de l'ensemble de la chaine est présenté afin de comprendre les différentes étapes qui composent un système audio. Un état de l'art présente les différents types de haut-parleurs ainsi que l'électronique associé les plus couramment utilisées dans les systèmes embarqués. Le second axe de recherche propose une approche globale : une modélisation électrique du haut-parleur (tenant compte d'un nombre optimal de paramètres) permet à un électronicien de mieux appréhender les phénomènes non-linéaires du haut-parleur qui dégradent majoritairement la qualité audio. Il en résulte un modèle viable qui permet d'évaluer la non-linéarité intrinsèque du haut-parleur et d'en connaitre sa cause. Les résultats des simulations montrent que le taux de distorsion harmonique intrinsèque au haut-parleur est supérieur à celui généré par un amplificateur. Le troisième axe de recherche met en avant l'impact du contrôle du transducteur. L'objectif étant de savoir s'il existe une différence, du point de vue de la qualité audio, entre la commande asservie par une tension ou par un courant, d'un micro-haut-parleur électrodynamique. Pour ce type de transducteur et à ce niveau de la modélisation, le contrôle en tension est équivalent à contrôler directement le haut-parleur en courant. Néanmoins, une solution alternative (ne dégradant pas davantage la qualité audio du signal) pourrait être de contrôler le micro-haut-parleur en courant. Le quatrième axe de recherche propose d'adapter les spécifications des amplificateurs audio aux performances des micro-haut-parleurs. Une étude globale (énergétique) démontre qu'un des facteurs clés pour améliorer l'efficacité énergétique du côté de l'amplificateur audio est la minimalisation de la consommation statique en courant, en maximalisant le rendement à puissance nominale. Pour les autres spécifications, l'approche globale se base sur l'étude de l'impact de la spécification d'un amplificateur sur la partie acoustique. Cela nous a par exemple permis de réduire la contrainte en bruit de 300%. Le dernier axe de recherche s'articule autour d'un nouveau type de transducteur : un micro-haut-parleur en technologie MEMS. La caractérisation électroacoustique présente l'amélioration en terme de qualité audio (moins de 0,016% de taux de distorsion harmonique) et de plage de fréquence utile allant de 200 Hz à 20 kHz le tout pour un niveau sonore moyen de 80dB (10cm). La combinaison de tous les efforts présente un réel saut technologique. Enfin, la démarche globale d'optimisation de la partie électrique a été appliquée aux performances du MEMS dans la dernière section, ce qui a notamment permis de réduire la contrainte en bruit de 500%.
3
Garud, Meera. "Cricket Inspired micro Speakers." Thesis, 2019. https://etd.iisc.ac.in/handle/2005/4585.
Full textAbstract:
MEMS technology has ushered in a new era of miniaturized sensors and actuators. Many
smart devices and systems are being developed using these sensors. Home automation
is now a widespread reality owing to the development of affordable miniature devices.
Wearables like smart watches and point-of-care medical devices have brought positive
changes in the healthcare industry. Also, at global scale, these sensors and actuators find
their place in tracking weather changes and remote sensing applications.
Many of these micro and nano systems communicate with humans using
electroacoustic devices. They can take in voice input, process it and give out voice
instructions/suggestions using a system made of microphones and audio speakers.
However, when we compare the sizes of all the different sensors and actuators with the
size of an audio speaker, we see that audio speakers have not really achieved
miniaturization. For example, in a standard smartphone a mini audio speaker is still 8
times larger in volume when compared with a MEMS microphone. An audio speaker is
still struggling to get into micron size range. This further limits the extent to which a
smart device can reduce in size. The size reduction of the audio speaker, if possible, will
lead to an overall size reduction of smart devices. We inspect the intricacies involved in
miniaturization of an audio speaker and explore a possible solution by combining silicon
MEMS technologies with nature inspired design for the same.
In this work, we present two unconventional approaches to build electrostatically
actuated thin audio speakers. First, we present a bio-mimetic micro-speaker inspired by
the sound production mechanism of field crickets. This design uses peripheral actuation
unlike the usual full area actuation in the conventional electrostatic speaker designs or
unlike the electrodynamic speaker designs where the diaphragm is directly actuated by
magnet-coil partially covering the central area of the vibrating diaphragm. Also, as in the
cricket’s sound production mechanism, we design to take advantage of the resonance.
Our speaker essentially uses a silicon diaphragm created by etching out patterned
cavities in the handle layer of an SOI wafer and controlled lateral etch of the buried
oxide to create closely spaced top and bottom annular electrodes for peripheral actuation.
These electrodes are used to drive the diaphragm with audio signal close to its resonance.
The open cavity provides an incredible advantage in terms of increasing the pull-in
voltage enormously. While we demonstrate the working of these micro-speakers with
several audio signals, the development must continue with an array of such speakers for
attaining a flat response over audible frequency range in order to make them
commercially viable. The second novel design to build wafer thin loudspeakers is based
on an accidental discovery we made during testing of the cricket inspired speakers. We
demonstrate how two simple pieces of silicon stacked loosely together and actuated with
appropriate electrical signal produce sound. The theoretical explanation is given behind
the new design idea, whose foundation is electrostatic actuation. Also, a few initial
results for the thin speakers developed with this design are presented
4
Ma, Yi-Fan, and 馬宜凡. "The Study of Finite Element Analysis of Micro-Speakers." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/fgn382.
Full textAbstract:
碩士國立臺北科技大學
車輛工程系所
105
Micros-speakers are key components of portable devices such as computer, communication and consumer electronics. The aim of this study is to investigate the acoustic performance of rectangle micro-speaker by FEM simulation with COMSOL Multiphysics. Two simulation methods are applied, one is analog circuit analysis combined with FEM and the other is use FEM only. The simulation results are agreed with experimental data, especially the FEM one. It can save the time and cost for acoustic performance analysis at the stage of design.
5
Liu, Min-Ting, and 柳旻廷. "Application of Finite Element Method for Micro-Speakers Parametric Study." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/7rckw3.
Full textAbstract:
碩士國立臺北科技大學
車輛工程系所
105
As technology progresses, not only powerful function is demanded in electronic devices, public also has aspiration for having a thinner, and smaller exterior. As speaker’s volume influence its’ performance directly, the public’s requirement may cause limitations in designing it. Beside, development course is also compressed to fulfill customers’ expectations. To develop optimized sound performance and make best efficacy in the low frequency field, and to reduce the entire cost, running simulation is no doubt a tendency. Types of notebook speakers were collected and analyzed. After measuring those speakers’ length, width, and height, a standard speaker box was defined not to be larger than all of them. Finite element analysis software “COMSOL Multiphysics” was used to find the best design, and confirm the result with a true sample. Through the simulation process, the influences of different sizes of bass reflex tubes in low frequency area’s performance and their frequency response level were discovered. And, the best volume scale of bass-reflex tube was found. Results of the study were expected to let designers find the best volume scale in the initial stage, and most importantly, to develop a performance-optimized speaker system with minimum costs and time.
6
Wang, Chia-Ying, and 王嘉瑩. "Optimal Design for Speakers of Cellular Phones Using Micro-Genetic Algorithm." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/36207037754413528004.
Full textAbstract:
碩士逢甲大學
航太與系統工程所
95
The quality of a speaker is determined by its frequency response. A high quality and sensitivity are critical to achieving an ideal design of speakers. However, the influence parameters of a speaker design are quite a lot. In the past, most of the speaker designs were implemented based on the trial-and-error method and by the designer''s experiences. Hence the design process are not only time consuming but costly. In the thesis, an equivalent circuit was built to predict the frequency response of speakers and to determine the quality of speakers. We use a parameter study to determine the influence of electro-mechano-acoustical parameters on the performance of the speakers. This study combines the equivalent circuit method and state-of-the-art micro-genetic algorithm to optimize the design parameters. It is hoped that this study can provide an optimal design technique for the speaker manufactures in Taiwan.
7
Cai, Chang, and 蔡長安. "Design and Analysis of Enclosure and Open Hole of Micro-speakers." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/46459c.
Full textAbstract:
碩士國立臺北科技大學
車輛工程系所
95
Recently, audio performance becomes an important issue of the 3C products such as mobile phone and notebook. Micro-speakers are widely used in these products. The audio performance depends on the enclosure and open holes design. The aim of this research is to study the effect of the enclosure (front and rear) and also the size and pattern of open holes. Experiments are measured with the CLIO audio test system in a semi-anechoic room. The front-rear enclosure and open hole can be modeled as electric components in an analogous circuit of the EMA (Electro-Mechano-Acoustical) system. It can effectively simulate the audio performance in the product design stage.
8
Godthi, Vamsy. "Dynamics Of Cricket Song Towards Nature-inspired MEMS Speakers." Thesis, 2015. https://etd.iisc.ac.in/handle/2005/2571.
Full textAbstract:
The clever designs of natural transducers are a great source of inspiration for man-made systems. At small length scales, there are many transducers in nature that we are now beginning to understand and learn from. Here, we present an example of such a transducer that is used by field crickets to produce their characteristic song. This transducer uses two distinct components—a file of discrete teeth and a plectrum that engages intermittently to produce a series of impulses forming the loading, and an approximately triangular membrane, called the harp, that acts as a resonator and vibrates in response to the impulse-train loading. The file-and-plectrum act as a frequency multiplier taking the low wing beat frequency as the input and converting it into an impulse-train of sufficiently high frequency close to the resonant frequency of the harp. The forced vibration response results in beats producing the characteristic sound of the cricket song. Based on various experimental observations reported in the literature, we model the sound production mechanism as consisting of three stages—actuator, frequency multiplier, and amplifier. We then examine how different features of the forewing govern the sound production. With careful experiments on the harp, we estimate the actual modulus of the harp cuticle and also measure the morphological features of the forewings of different field cricket species. Using this data, we construct a finite element model of the harp and carry out modal analysis to determine its natural frequency. We fine tune the model with appropriate elastic boundary conditions to match the natural frequency of the harp of a particular species—Gryllus bimaculatus. We model impulsive loading based on a loading scheme reported in the literature and predict the transient response of the harp. We show that the harp indeed produces beats and its frequency content matches closely that of the recorded song. Subsequently, we use our FEM model to show that the natural design is quite robust to structural perturbations in the file. The characteristic song frequency produced is unaffected by small variations in the spacing of file-teeth and even by larger gaps. We then attempt to predict a scaling law that crickets must use for spectrum allocation. We use our FEM model, with measurements and computations, to arrive at a predictive model that relates call frequencies of field crickets to the harp dimensions. We verify the validity of this model by using the measured dimensions of harps of nine field cricket species. We then use our model to provide possible explanations as to why the song frequency of various field crickets in our study is bounded between 3.1 kHz and 6.8 kHz. We also show that we are faced with similar challenges as crickets when designing miniature MEMS (Micro-Electro-Mechanical Systems) speakers. We present a design of MEMS speakers that is inspired by how the crickets actuate. We have been able to realize our first prototypes using simple fabrication processes. By electrostatically actuating the MEMS devices, we obtain a sound pressure of 70 dB SPL at a distance of 10 cm. We believe that with a few design and fabrication iterations, we will be able to achieve a much higher sound pressure output from the MEMS speakers.
9
Godthi, Vamsy. "Dynamics Of Cricket Song Towards Nature-inspired MEMS Speakers." Thesis, 2015. http://hdl.handle.net/2005/2571.
Full textAbstract:
The clever designs of natural transducers are a great source of inspiration for man-made systems. At small length scales, there are many transducers in nature that we are now beginning to understand and learn from. Here, we present an example of such a transducer that is used by field crickets to produce their characteristic song. This transducer uses two distinct components—a file of discrete teeth and a plectrum that engages intermittently to produce a series of impulses forming the loading, and an approximately triangular membrane, called the harp, that acts as a resonator and vibrates in response to the impulse-train loading. The file-and-plectrum act as a frequency multiplier taking the low wing beat frequency as the input and converting it into an impulse-train of sufficiently high frequency close to the resonant frequency of the harp. The forced vibration response results in beats producing the characteristic sound of the cricket song. Based on various experimental observations reported in the literature, we model the sound production mechanism as consisting of three stages—actuator, frequency multiplier, and amplifier. We then examine how different features of the forewing govern the sound production. With careful experiments on the harp, we estimate the actual modulus of the harp cuticle and also measure the morphological features of the forewings of different field cricket species. Using this data, we construct a finite element model of the harp and carry out modal analysis to determine its natural frequency. We fine tune the model with appropriate elastic boundary conditions to match the natural frequency of the harp of a particular species—Gryllus bimaculatus. We model impulsive loading based on a loading scheme reported in the literature and predict the transient response of the harp. We show that the harp indeed produces beats and its frequency content matches closely that of the recorded song. Subsequently, we use our FEM model to show that the natural design is quite robust to structural perturbations in the file. The characteristic song frequency produced is unaffected by small variations in the spacing of file-teeth and even by larger gaps. We then attempt to predict a scaling law that crickets must use for spectrum allocation. We use our FEM model, with measurements and computations, to arrive at a predictive model that relates call frequencies of field crickets to the harp dimensions. We verify the validity of this model by using the measured dimensions of harps of nine field cricket species. We then use our model to provide possible explanations as to why the song frequency of various field crickets in our study is bounded between 3.1 kHz and 6.8 kHz. We also show that we are faced with similar challenges as crickets when designing miniature MEMS (Micro-Electro-Mechanical Systems) speakers. We present a design of MEMS speakers that is inspired by how the crickets actuate. We have been able to realize our first prototypes using simple fabrication processes. By electrostatically actuating the MEMS devices, we obtain a sound pressure of 70 dB SPL at a distance of 10 cm. We believe that with a few design and fabrication iterations, we will be able to achieve a much higher sound pressure output from the MEMS speakers.
10
Liu, Feng-Ming, and 劉峰銘. "The Study of Cavity Design and Testing of Micro Speakers for the Smart Mobile Device." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/b44uy2.
Full textAbstract:
碩士國立臺北科技大學
車輛工程系所
101
Impedance curves of a micro-speaker are not the same for different test methods. It influences the calculation of T-S parameters which are used to simulate the frequency response curve of a micro-speaker. Constant current testing and constant voltage testing are two common test methods for AC impedance measurement. Actually, the micro-loudspeaker in the circuit is driven by required power which let micro-speaker to achieve the specific capability. But different driving voltages cause the impedance of the loudspeaker varied which induces nonlinear characteristics. The purpose of this paper is to investigate impedance properties of a loudspeaker by using different testing methods, and also to study the linear capability of impedance and sound pressure frequency response at different experiment voltages. Measured sound pressure frequency response curves are compared with simulations from equivalent circuit method by using T-S parameters measured at different voltages. The differences between simulation and measured data are interpreted with the modal analysis of diaphragm. The micro-loudspeakers usually want to integrate into the smart mobile device, because internal structure of space and exterior covering of shape design different, to affect applications are also different chamber volume. Therefore, the different back and front chamber of volumes, housing holes, materials and thicknesses, using EMA analog circuit are analyzed by the experiment and simulation result.
11
Welthagen, Denise Anne. "Urban township students' reading : micro-genetic studies in an academic support school." Thesis, 2014. http://hdl.handle.net/10210/10758.
Full textAbstract:
M.Ed. (Educational Linguistics)This study focuses on the reading proficiency in English of black students who are attending an academic support school. From observations made on the difficulties experienced by many students in successfully completing reading tasks in the classroom., it appeared that many of these students were not proficient readers. As reading is a multi-dimensional research phenomenon, various dimensions of reading, which include bottom-up proficiency, top-down proficiency, metacognition, and affective and socio-cultural factors, have been investigated. While reading proficiency is the focus of the study, the relationship between reading and language proficiency as well as the influence of the sociocultural and educational background of the student on his reading have also been investigated. The research design for investigating the problem included a review of literature on the various reading models and on reading pedagogy, as well as on the relationship between language proficiency and reading proficiency. Literature on the influence of a disadvantaged sociocultural and educational background on reading proficiency was also reviewed. From these readings it was evident that reading is a complex process, the nature of which is still being investigated by reading theorists. Furthermore, the literature reviewed seemed to indicate that there is a relationship between language proficiency and reading proficiency, as well as a relationship between the sociocultural and educational background of the student and reading proficiency. The literature review was followed by a micro-genetic investigation of the research problem by a full participant researcher. Data were collected from nine students and processed. The findings indicate that most of the students are not proficient readers even though their bottom-up proficiency is adequate. Furthermore, it was found that a relationship between language proficiency and between sociocultural status and educational disadvantage and reading proficiency, does appear to exist. To conclude the investigation, suggestions for teacher training in reading pedagogy and for the teaching of reading in secondary schools to English Second Language readers were made. Finally, a model for reading pedagogy, which includes various aspects of the reading process, was devised.
12
Mittal, Saurabh. "Frequency-Tuning and Dynamic Simulation of Electrostatically Actuated Beams." Thesis, 2014. http://etd.iisc.ac.in/handle/2005/2952.
Full textAbstract:
The resonance frequency of electrostatically actuated micromachined beams can be tuned substantially by applying a DC voltage bias, first by decreasing the frequency until the onset of pull-in and then by increasing it by the virtue of contact. With the objective of modeling and designing the micromechanical structures after pull-in, a semi-analytical method was developed to determine the length of the contact between the beam and the substrate. The semi-analytical method which is validated on the straight beams is extended for the folded beam structures. This method provides a tool to the microsystem designer to quickly evaluate the deformed configuration of the folded beams after pull-in without the time-intensive contact analysis. This tool is used to design the micro‐speaker elements suitable for emitting low frequency sounds. Multiple instabilities after the pull-in were numerically observed and it was shown that the resonant frequency of an L-shaped beam can be varied in different frequency bands. The speaker element can emit any frequency in a given range, as the resonant frequency of the beam structures can be tuned both before and after pull-in. Operating the speaker element at resonance maximizes the efficiency of the speaker design because the amplitude of vibration is maximum at the resonance frequency. Furthermore, the interplay between the torsional and bending loads is used to minimize the out-of-plane deflection under self weight. A selection criterion is employed to choose a beam structure with optimum stiffness and natural frequency.
Beam-based micro-speaker element designs with single and multi-layered suspended structures are proposed. Practical considerations such as volume displacement, mode shapes and dynamic coupling are discussed, on the basis of which design guidelines for a speaker element are proposed. Squeeze film effects and nonlinearity due to the midplane stretching is integrated into the transient analysis model to analyze the effect on the stroke of beam operating at resonance. A comparison between various speaker elements is presented.
13
Mittal, Saurabh. "Frequency-Tuning and Dynamic Simulation of Electrostatically Actuated Beams." Thesis, 2014. http://etd.iisc.ernet.in/handle/2005/2952.
Full textAbstract:
The resonance frequency of electrostatically actuated micromachined beams can be tuned substantially by applying a DC voltage bias, first by decreasing the frequency until the onset of pull-in and then by increasing it by the virtue of contact. With the objective of modeling and designing the micromechanical structures after pull-in, a semi-analytical method was developed to determine the length of the contact between the beam and the substrate. The semi-analytical method which is validated on the straight beams is extended for the folded beam structures. This method provides a tool to the microsystem designer to quickly evaluate the deformed configuration of the folded beams after pull-in without the time-intensive contact analysis. This tool is used to design the micro‐speaker elements suitable for emitting low frequency sounds. Multiple instabilities after the pull-in were numerically observed and it was shown that the resonant frequency of an L-shaped beam can be varied in different frequency bands. The speaker element can emit any frequency in a given range, as the resonant frequency of the beam structures can be tuned both before and after pull-in. Operating the speaker element at resonance maximizes the efficiency of the speaker design because the amplitude of vibration is maximum at the resonance frequency. Furthermore, the interplay between the torsional and bending loads is used to minimize the out-of-plane deflection under self weight. A selection criterion is employed to choose a beam structure with optimum stiffness and natural frequency.
Beam-based micro-speaker element designs with single and multi-layered suspended structures are proposed. Practical considerations such as volume displacement, mode shapes and dynamic coupling are discussed, on the basis of which design guidelines for a speaker element are proposed. Squeeze film effects and nonlinearity due to the midplane stretching is integrated into the transient analysis model to analyze the effect on the stroke of beam operating at resonance. A comparison between various speaker elements is presented.
14
Chang, Sheng-Yuan, and 張勝淵. "Standing waveanalysis and improvement of micro speaker." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/97794608348341814876.
Full textAbstract:
碩士華梵大學
機電工程學系
102
This article is based on a single experiment with normal headphones, make improvements based on the basic structure and the impact of general internal standing waves generated by a small headset, which is based on experiments with laser displacement meter miniature microphone for transient and steady-state parties face headphone experiment comparing the experimental data integration and improved headphones monomer observed headphones standing with all aspects of data performance. Keywords: standing, mini speakers, natural frequency, peak
15
Huang, Jih-Chung, and 黃日中. "A Glottal Micro-Motion-Assisted Speaker Identification Method." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/28193698841449123729.
Full textAbstract:
碩士國立中正大學
電機工程所
95
Abstract Speaker identification is a kind of biological authentication technology, which uses personal characteristics to distinguish users. This technology becomes more and more important as the recognition technology matures. Since only a small number of voice features has been used to characterizes human voice, and the performance of speaker identification is easily disturbed by noise and personal health and emotions. Traditional speaker identification must apply recognition technologies in noiseless environments for high performance. This thesis proposes a novel glottal vibration feature to improve the traditional speaker identification system. This study stems from the fact that human sound is caused by the vibration of vocal cord. Therefore, we extract both the features of the sound and glottal motion and compares their differences. The glottal motion was proven to be a good characteristic of human based on the features and the proposed classifier in the experiments. The results show that high accuracy of 92% was obtained with only glottal motion signal. The accuracy is increased to 96% with combined traditional speaker identification and glottal motion. Even in noisy environments, using glottal signal can achieve an accuracy of 88%. In the final experiment, we also study the effect of noise to the glottal-signal-assisted speaker identification system in different signal to noise ratio. The propose system is demonstrated to be effecting and noise resistant.
16
林圓紹. "Study of material properties of micro-speaker diaphragms." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/88bj6f.
Full text
17
Wang, Yi-Ting, and 王怡婷. "Analysis and Experiment Verification of a Micro-speaker." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/37580944579491912845.
Full textAbstract:
碩士中原大學
機械工程研究所
93
In this study, a moving-coil type micro-speaker is investigated for the demands on high sound quality for commercial cell phones. To put emphasis on high frequency responses of the micro-speaker, one of commonly-seen means is adoption of corrugation on the diaphragm. To confirm the effectiveness of the corrugation, the diaphragm model is constructed by finite elements to extract the dynamic modes. These modes are then combined with the magneto-electrical model of voice coil motor (VCM) that is attached to the bottom side of the diaphragm. The modeling of VCM is carried out through finite elements on the magnetic field around VCM. To complete modeling, the acoustic effects of the air are also modeled. Assembling all derived system equations and solving them, the frequency response of the micro-speaker can be obtained. Results of the theoretical analysis are confirmed by experiments.
18
GENG-DUAN, HSU, and 許耕端. "Development of Damping Technique on Micro-speaker Diaphragm." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/09843391060957979663.
Full textAbstract:
碩士華梵大學
機電工程學系
102
A new damping technique for improving the transient response of the micro-speaker is proposed. The damping technique is an ultra thin film whose first resonance frequency is coincidence with the resonance frequency of the micro speaker diaphragm. As the film is close to the diaphragm, the standing wave of the micro speaker can be eliminated by the motion of the resonance film. Several types of resonance film, including different fundamental frequencies, thickness, locations, distances from the diaphragm, are studied. Result shows that the resonance film is very effective on improving the standing wave of the side dome as the film is ultra thin and ultra close to the diaphragm. After mounting the resonance films, the transient response of the diaphragm can be effectively eliminated. The sound pressure in the frequency domain can be also effectively eliminated by 2.5 dB.
19
Huang, Che-Yung, and 黃哲庸. "Acoustic Analysis of Geometric Appearance on Micro-speaker." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/j8fae2.
Full textAbstract:
碩士國立臺北科技大學
車輛工程系所
105
This thesis studies the sound property in different geometric appearances of Micro-speaker diaphragm. In the first part, the finite element code COMSOL Mutiphysics is used to simulate the sound property of frequency response and impedance in 0916 micro-speaker. The simulation results of COMSOL are compared with the experimental data obtained after measurement that can verify accuracy of simulation frame. This simulation frame is applied in different geometric appearance of micro-speaker diaphragm to simulate the sound pressure level and impedance and sound directivity. Compare the simulation result. This simulation can predict the trend of the sound from geometric appearance as well.
20
Tsai, Tung-Lin, and 蔡東霖. "Parameter Analysis of Diaphragm Patterns of the Micro-speaker." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/v94ban.
Full textAbstract:
碩士國立臺北科技大學
車輛工程系所
99
This paper studies diaphragm pattern design of the micro-speaker by parameter analysis. In recent years, electronic consumer products boomed rapidly such as smart phones, tablet PCs, 3D TVs etc. For competition the demand for high sound quality is increasing. Micro-speakers are also requested to have wide frequency range and good sound quality. Diaphragm pattern design is crucial to the performance of micro-speakers. By finite element method (FEM), the first resonance frequency f_0 can be calculated. When the first resonance frequency is lower, the working frequency range can be extend to the lower frequency. To improve sound quality, micro-speaker must reduce distortion. Distortion might be caused by resonances of diaphragm. In this paper, modal analysis of the micro-speaker is carried out by FEM from 20 Hz to 20 KHz. Mode amount and mode types affect the performance of the micro-speaker are discussed .
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張瑞成. "Research and Application of Rectangle Micro-Speaker for Portable Device." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/kbnn22.
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碩士逢甲大學
電聲碩士學位學程
103
Currently, importing simulation to electric-acoustic products design is kind of trend. It could short the lead time and reduce cost. In this thesis, build a simulation model for rectangle micro-speaker to estimate Bl(x), Km(x), frequency response and distortion. Using finite element method commercial software FEMM to simulate Bl(x) could get higher magnetic force and sensitivity. Using finite element method commercial software COMSOL to simulate Km(x) could get flat and symmetrical curves. Using lump model to simulate frequency response curve could find the optimize design of structure, Bl(x) and else. In the case, increasing height of polar piece could enhance sensitivity. To change the magnet size or level is not the only way to get higher sensitivity. Shifting the top point of diaphragm pattern from fame side to voice coil side could reduce the distortion in effective bandwidth range. To increase height of diaphragm pattern could reduce distortion below effective bandwidth range. Changing pattern from inside to outside could reduce distortion between 1/2 harmonic of F0 and 2nd harmonic of F0. By subjective listening test (Jury Test), confirmed the design of the rectangle micro-speaker have a better sound quality. Above analysis, using FEM commercial software and lump model assist in the design phase of the micro-speakers can predict the frequency response and distortion. Not only solve the design issue, but also save the time and cost.
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Yuan, Hsu-Pang. "Dynamic Modeling and Experimental Verification of a Micro-speaker with Enclosure." 2006. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0017-1901200710325062.
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Hsu-Pang, Yuan, and 許龐淵. "Dynamic Modeling and Experimental Verification of a Micro-speaker with Enclosure." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/99891132519700381522.
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碩士中原大學
機械工程研究所
94
In this study, the simulation results of the diaphragm of the micro-speaker considered with different corrugation angles, 15, 45, 75 degrees, respectively, are presented in the study using dynamic analysis, which includes electromagnetic, mechanical, and acoustical modeling for respective subsystems. The frequency responses of the three cases can be obtained and discussed the discrepancy of the results. On the other hand, the moving-coil type micro-speaker considered with fluid-structure interaction of the diaphragm and the air within the micro-speaker is also investigated. In order to predict the response of the experiment data at high frequency, the air enclosure within the micro-speaker is taken into account. To simplify the building process of finite element model of the air enclosure, the corrugated profiles of the diaphragm is neglected. The simulation result can be obtained via ANSYS harmonic analysis and compared with the experiment data.
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Tsung, Huang Chao, and 黃朝宗. "Magnetic Circuit Analysis and Distortion Experiment Verification of a Micro Speaker." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/54280173778963185422.
Full textAbstract:
碩士國立高雄應用科技大學
模具工程系碩士班
95
Magnetic Circuit Analysis and Distortion Experiment Verification of a Micro Speaker Student： Chao Tsung Husng Advisor： Ching-yu Yang Department of Mold and Die Engineering National Kaohsiung University of Applied Sciences ABSTRACT The study investigates the important parameters for the performance of a micro speaker. The parameter includes the position of the magnetic gap, the voice coil layer and the winding width in the different types of micro-speaker. The finite element method commercial code FEMM is used to simulate and analyze the features of the micro-speaker in that the magnetic flux density and flux distribution is possible to predict. The distortion of the micro-speaker caused by the non-uniform flux distribution is analyzed based on the theories of vibration and magnetism. Moreover, it also unveils that the effects of mechanical structure and materials on the magnetic flux of a speaker. According to the analysis results, the micro-speaker can be manufactured. As well, a comparison of the characteristic between the theoretical design value and the experimental value is made. The result shows that it can provide valuable data to improve the performance of the micro-speaker system and it contributes to develop a new speaker in the future. Keyword:voice voice coil 、voice coil layers、 magnetic gap 、 winding width magnetic flux density 、 flux distribution、distortion
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Hsu, Wen-Hsin, and 許文馨. "A Study on Output Analysis and Quality Improvement of Micro-Speaker." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/72537385378913578189.
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碩士臺灣大學
工程科學及海洋工程學研究所
98
An application of feedback linearization control for micro-loudspeakers is presented in this paper. With inverse dynamic processor, signal distortion caused by loudspeaker nonlinearities can be compensated. First of all, the loudspeaker system separates into three parts: electrical, mechanical and radiation to build the classical linear and nonlinear models. Then converting the theoretical model into discrete-time system and using digital processing technique to simulate the output of the loudspeaker system. The theoretical model is verified by comparing the frequency response of real loudspeaker to the numerical result of simulation. The agreement is good. The second part is to investigate the effect of the parameter variation on the output of the loudspeaker. In this study only the transduction coefficient varies with displacement is considered. This nonlinearity will cause unwanted harmonics in the response of loudspeaker. To reduce this nonlinear effect, a feedback linearization method from nonlinear control theory is applied to the nonlinear loudspeaker model. Numerical simulation reveals that the feedback linearization method can cancel the harmonic signals effectively. Finally, the present approach is applied on the nonlinear control of the real loudspeaker. The result is some parts of harmonics are reduced obviously. But some output sound signal seems not be improved under control. This may due to the incorrect values of transduction coefficient. But it still needs a further study.
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Wang, Hung-Chi, and 王泓棋. "Analysis and experimental confirmation of the micro speaker for the mobile phone." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/93865864542934470452.
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碩士國立高雄應用科技大學
模具工程系碩士班
96
This dissertation focused on general micro speaker design of mobile phone to find out different characteristic caused by materials changes. All simulation and experimental confirmations are based on magnet circle system, vibration system and acoustics system theory. The research uses finite element analysis software to calculate the magnet circle system, magnetic field distribution status and diaphragm material characteristic vs. impedance curve (Fo) and frequency response curve (SPL) influence. Finally, measure the characteristics of different specific micro speakers and compare with simulation results. The results can provide an importance reference, and shorten product development lead-time and enhance its performance of micro speakers.
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Tseng, Mu-Tsun, and 曾木村. "A study on the characteristics and singular case of a Micro-speaker." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/47737511079405711515.
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碩士國立高雄應用科技大學
模具工程系碩士班
95
In these days, micro speaker has become smaller with higher performance and lower distortion along with the improved technology. Speaker industry generally focuses on the design of the products and place less attention on the materials and assembly techniques of the products. It is important to realize that materials and assembly techniques will judge the different characteristics and qualities of sounds of the products. In this thesis, we mainly discuss the MP3 earphone units, i.e. 15.4mm Micro speaker, which are constructed by moving coil inside the magnetic fields. These are based on the electronic, magnetic and acoustic, powers, combined with the dynamic theories existed simultaneously in the speaker system. One of the main sections of the thesis is finding the best parameter and the most significant factors which influence the micro-speaker by Taguchi methods for the different assembly techniques of a Micro speaker in the industry. Furthermore, we discuss the characteristics and singular case of Fo, SPL and THD of a Micro speaker. These analytical results will make more contributions in increasing performance and quality of the micro-speaker.
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Zhou, Yong-Xin, and 周永昕. "Application of the Taguchi method to optimize micro speaker module design for bass extension." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/442q8y.
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碩士國立臺北科技大學
車輛工程系
106
With the development of the era, people are increasingly demanding sound quality, so the study of this paper focuses on designing a method of implementing an extra sound tube in the front speaker of micro chassis to make the low frequency have an extended effect. At first, simulate the structure of speaker by COMSOL and change the capacity of the front speaker, size of the sound hole, length of the sound tube, and the cross-sectional area of the sound guide to figure out the best parameter design through orthogonal table L_9 (3^4 ) in the “Taguchi Method”. Thus, we produce a physical speaker based on the redesigned optimization parameter. Finally, we authenticate the accuracy of the simulation through practical test.
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Jiang, Zhen-Qiang, and 江振強. "Speaker Recognition Based on Electromagnetic Glottal Micro-Motion Detection System and Related CMOS VCO Design." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/25649670724391755222.
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碩士國立中正大學
電機工程所
96
Speaker identification is a kind of biological authentication technology, which uses personal vocal characteristics to distinguish the users. This technology becomes more and more important along with the increasing need of recognition system, and can be extensively applied to various applications. In tradition, the speak identification is based on the vocal voices recorded by the microphone, which is easily disturbed by surrounding noises. Moreover, the user’s health condition and emotion could also affect the identification accuracy severely. Due to this reason, this thesis proposes using the glottal vibrations as a new biological feature, which can significantly reduce the effects from the background noises and increase the identification accuracy as well. Based on the fact that human sounds are initially generated by the vibrations of vocal cord, a radar-based glottal micro-motion detection system is developed to capture the vibration waveforms during speech. At the same time, the vocal voices are recorded by the microphone as well. Both signals are input to the identification system to recognize the speaker. The speaker identification analysis program is self-developed using Labview and matlab software, and the sample group consists of 10 people. The experimental results show that both glottal signals and vocal signals can achieve near 100% accuracy in a noiseless environments. However, with background noise, the vocal signals drops to 82% accuracy while the glottal signals can still maintain ~95% accuracy, which demonstrates its noise resistant capability. The second part of this thesis work is to design a VCO CMOS MMIC for next-generation’s electromagnetic glottal micro-motion detection system. This circuit is using stacked configuration to achieve dual outputs with 2.4 GHz and 5.2 GHz operation.
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林琇梅. "Arc Ion Plated Multilayer Diamond-like Carbon Film on Polymeric Diaphragm for Micro Speaker Applications." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/91384100471638757182.
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