Microphone Research Papers - Academia.edu (original) (raw)

In the context of the development of MEMS microphones designed for the measurement of high frequency waves and weak shockwaves in air, it is necessary to define new calibration methods in order to estimate accurately the frequency... more

In the context of the development of MEMS microphones designed for the measurement of high frequency waves and weak shockwaves in air, it is necessary to define new calibration methods in order to estimate accurately the frequency response of new sensors. For this purpose, we will present the principle of a calibration method based on the measurement of weak shockwaves generated by a spark source. The influence of the sources of error will be discussed. To demonstrate the interest of the method, measured responses of 1/8" microphones will be given for various mountings.

Now a day, peoples have multiple bank accounts so money transactions play a vital role in the nature of trade. Today, ATMs and Credit cards are used for this purpose, the authentication of these transactions are unsecure. To overcome this... more

Now a day, peoples have multiple bank accounts so money transactions play a vital role in the nature of trade. Today, ATMs and Credit cards are used for this purpose, the authentication of these transactions are unsecure. To overcome this shortcoming of money transactions, we proposes the idea of using fingerprints of customers as login multiple banking password in place of traditional pin number. Here, if the fingerprint is recognized, then it display the multiple banking screen. Then we can choose the bank which we need for transaction. The remaining feature are same as i.e., a reference fingerprint of the nominee or a close family member of the customer can be used if the customer is not available in case of emergencies. This proposed business model helps the society, mainly the rural people, by enhancing the security using Fingerprint recognition in Digital image processing. As the fingerprint of every person is unique and unchangeable, this biometric feature is used over the others

to the extremely intense materiality involved in the conversation and connection with the spiritual dimension. The transcendent is not only spiritual but also deeply physical, both felt and embodied. In this sense, Híbridos can serve as a... more

to the extremely intense materiality involved in the conversation and connection with the spiritual dimension. The transcendent is not only spiritual but also deeply physical, both felt and embodied. In this sense, Híbridos can serve as a phenomenological study of Brazilian ritual: the practice of spirituality is displayed in a very direct and dramatized way, providing the viewer with a cinematographic experience that is not only about the invisible or ineffable but also about a dimension of life that is touchable, concrete, and physically present. Another positive feature of Híbridos is the form in which the project was released: it is under a free Creative Commons license, which means that it is possible to download music, watch interviews, and share content at no cost. This format also gives back to the communities, mediums, and musicians involved, as they can access and use their images and sounds, building a new perspective of themselves and their practices. And last but not least, the work of researching, filming, editing, and sound design, as well as the website, reveals a carefully curated process that translates into a very high quality final product and a beautiful piece of filmography.

This paper presents an application-oriented approach to Acoustic Source Localization using a coincident microphone array. Multiple processing blocks are presented to generate a reactive, yet stable Direction of Arrival estimation tuned... more

This paper presents an application-oriented approach to Acoustic Source Localization using a coincident microphone array. Multiple processing blocks are presented to generate a reactive, yet stable Direction of Arrival estimation tuned toward speaker tracking. Building on an energy based scanning method, individual characteristics, such as sound field directivity and static sound source positions are used for adaptive smoothing of the detected angle. The methods and resulting performance gain are discussed for the individual components of the algorithm. Objective performance is evaluated using simulated and recorded data. Audio quality is assessed using listening tests, which show a significant increase in subjective sound quality, noise suppression, and speech intelligibility when combining the tracker with a beamforming algorithm for coincident microphone arrays.

Performance of axial fan is found to reduce drastically when instability is encountered during its operation. Performance of an axial fan is severely impaired by many factors mostly related to system instabilities due to rotating stall... more

Performance of axial fan is found to reduce drastically when instability is
encountered during its operation. Performance of an axial fan is severely impaired by many factors mostly related to system instabilities due to rotating stall and surge
phenomenon experienced during its operation. The present work involves measuring the time domain sound signal in ducted axial fan under stable region at throttle positions 5 cm from the casing. Objective of the experiment is to measure the time domain sound signal in terms of decibel and comprehend the sound Characteristics in ducted axial fan by using sound spectrum analyser. Different types of time domain sound signals have been measured under stable region at throttle position 5 cm from the casing for different rotor speed and different graphs are plotted for ducted axial fan

This paper describes the conception, designs consideration and fabrication process of a novel MEMS microphone. The presented microphone not only uses a new architecture, the sensitive part being beams moving within the plane of the... more

This paper describes the conception, designs consideration and fabrication process of a novel MEMS microphone. The presented microphone not only uses a new architecture, the sensitive part being beams moving within the plane of the substrate, but also uses an innovative detection means with Silicon piezo-resistive nanogauges. Modelization will consider acoustic and mechanical interactions. Besides, at MEMS scale, accurate simulation of the sensor must take into account thermal and viscous boundary layers in acoustics, and we will show that the presented sensor takes benefit from these short scale effects, which leads to achieve theoretical resolution as low as 24dB.

This paper proposes a method for estimating the angle-dependent sound absorption coefficient of a large material sample using a compact microphone array. The method relies on the description of the pressure field as a pair of in-going and... more

This paper proposes a method for estimating the angle-dependent sound absorption coefficient of a large material sample using a compact microphone array. The method relies on the description of the pressure field as a pair of in-going and outgoing waves or using an image source model and stands as a generalization of the classical two-microphone method. The array includes an irregular spacing normal to the surface to avoid spatial aliasing. Furthermore, the benefit of additional microphones parallel to the sample is investigated, while keeping the array compact. The approach is validated against the transfer matrix method as well as against locally and non-locally reactive surface models and compared to the two-microphone method. The sensitivity of the estimation to uncertainties in the microphone positions is evaluated by means of a Monte Carlo approach. Measurements above melamine foam and gravel samples are presented and illustrate the reduced uncertainty in the sound absorption estimation. In particular, the proposed method exhibits improved robustness compared to the two-microphone method, especially at low frequencies.

This paper analyses the influence of microphone cavity geometry on beamforming measurements with a turbulent boundary layer present on the microphone array. A 16- microphone array was tested in the anechoic open-jet wind tunnel of the... more

This paper analyses the influence of microphone cavity geometry on beamforming measurements with a turbulent boundary layer present on the microphone array. A 16- microphone array was tested in the anechoic open-jet wind tunnel of the Delft University of Technology. The array was placed on a flat plate mounted flush with the exit nozzle of the wind tunnel. Microphones were installed in three different cavity geometries along with a flush mounted microphone array which was used as a baseline for comparison. The geometries include a chamfered-cylindrical hard-plastic cavity, a chamfered-cylindrical cavity made of melamine foam, and a chamfered-cylindrical cavity with star-shaped protrusions, also made of melamine. The recessed cavities were covered with a 0.026 mm gauge steelwire cloth. A speaker emitting white noise outside of the flow was employed as a sound source. Different flow velocities at the same sound power level for the speaker (and hence different signal-to-noise ratios) w...

This study looks at two ways of extracting a glottal waveform from recorded speech. One way is to inverse filter the flow at the mouth. Another is to inverse filter the microphone signal. Theoretically, the microphone signal is considered... more

This study looks at two ways of extracting a glottal waveform from recorded speech. One way is to inverse filter the flow at the mouth. Another is to inverse filter the microphone signal. Theoretically, the microphone signal is considered to be the equivalent of a first order differentiation of the flow signal recorded at the lips. Recording the oral airflow is more complicated than the recording of a microphone signal, as it requires the use of a mask, with constant adjustments during the recording. Recording of the microphone signal is more straightforward for the experimenter and less intrusive for the subject. If the two inverse filtering procedures can be shown to produce similar glottal flow waveforms for both types of recorded speech, this would support the use of only the microphone signal for those types of glottal flow analysis where the DC component of the flow is not essetial, making voice source analysis applicable in less specialised situations. In this study, we used ...

This paper presents novel minimally-invasive, catheter-based acoustic interrogation device for monitoring motility dynamics of the lower esophageal sphincter (LES). A micro-oscillator actively emitting sound wave at 16 kHz is located at... more

This paper presents novel minimally-invasive, catheter-based acoustic interrogation device for monitoring motility dynamics of the lower esophageal sphincter (LES). A micro-oscillator actively emitting sound wave at 16 kHz is located at one side of the LES, and a miniature microphone is located at the other side of the sphincter to capture the sound generated from the oscillator. Thus, the dynamics of the opening and closing of the LES can be quantitatively assessed. In this paper, experiments are conducted utilizing an LES motility dynamics simulator. The sound strength is captured by the microphone and is correlated to the level of LES opening and closing controlled by the simulator. Measurements from the simulator model show statistically significant (p < 0.05) Pearson correlation coefficients (0.905 on the average in quiet environment and 0.736 on the average in noisy environment, D.O.F. = 9). Measuring the level of LES opening and closing has the potential to become a valuable diagnostic technique for understanding LES dysfunction and the disorders associated with it.

Objective measurements using a sinusoidal sweep show that microphone angle has little effect on the frequency response of a guitar amplifier recording [1]. However, anecdotal evidence suggests that alterations to the microphone angle hold... more

Objective measurements using a sinusoidal sweep show that microphone angle has little effect on the frequency response of a guitar amplifier recording [1]. However, anecdotal evidence suggests that alterations to the microphone angle hold merit when recording ecologically valid sound sources. An ABX listening experiment was conducted with 20 participants to investigate whether microphone angles of 0, 30, and 60 degrees were audibly different to this cohort. Both dynamic and ribbon microphones were used and the loudness normalized guitar recordings were presented in solo and within a music mix. The experimental results suggest that microphone angles did not generate any perceivable changes to this cohort on this program material.

International audienceThis article traces the history of the Locustream Open Microphone Project, a network of open microphones that has streamed live soundscapes from locations around the globe since 2005. The author describes the human,... more

International audienceThis article traces the history of the Locustream Open Microphone Project, a network of open microphones that has streamed live soundscapes from locations around the globe since 2005. The author describes the human, collective , and technological aspects of this project as well as the creative research it has engendered

This article introduces and provides an assessment of a spatial-filtering algorithm based on two closely-spaced (∼1 cm) microphones in a behind-the-ear shell. The evaluated spatial-filtering algorithm used fast (∼10 ms) temporal-spectral... more

This article introduces and provides an assessment of a spatial-filtering algorithm based on two closely-spaced (∼1 cm) microphones in a behind-the-ear shell. The evaluated spatial-filtering algorithm used fast (∼10 ms) temporal-spectral analysis to determine the location of incoming sounds and to enhance sounds arriving from straight ahead of the listener. Speech reception thresholds (SRTs) were measured for eight cochlear implant (CI) users using consonant and vowel materials under three processing conditions: An omni-directional response, a dipole-directional response, and the spatial-filtering algorithm. The background noise condition used three simultaneous time-reversed speech signals as interferers located at 90°, 180°, and 270°. Results indicated that the spatial-filtering algorithm can provide speech reception benefits of 5.8 to 10.7 dB SRT compared to an omni-directional response in a reverberant room with multiple noise sources. Given the observed SRT benefits, coupled wi...

Monitoring the tool flank wear without affecting the throughput is considered as the prudent method in production technology. The examination has to be done without affecting the machining process. In this paper we proposed a novel work... more

Monitoring the tool flank wear without affecting the throughput is considered as the prudent method in production technology. The examination has to be done without affecting the machining process. In this paper we proposed a novel work that is used to determine tool flank wear by observing the sound signals emitted during the turning process. The work-piece material we used here is steel and aluminum and the cutting insert was carbide material. Two different cutting speeds were used in this work. The feed rate and the cutting depth were constant whereas the flank wear was a variable. The emitted sound signal of a fresh tool (0 mm flank wear) a slightly worn tool (0.2-0.25 mm flank wear) and a severely worn tool (0.4mm and above flank wear) during turning process were recorded separately using a high sensitive microphone. Analysis using Singular Value Decomposition was done on these sound signals to extract the feature sound components. Observation of the results showed that an increase in tool flank wear correlates with an increase in the values of SVD features produced out of the sound signals for both the materials. Hence it can be concluded that wear monitoring of tool flank during turning process using SVD features with the Fuzzy C means classification on the emitted sound signal is a potential and relatively simple method.