Showing papers in "Journal of the Acoustical Society of America in 2003"
TL;DR: The Atomic Processes in Plasmas Conference as mentioned in this paper is a bi-annual international conference on topics covering high-energy density plasmas, magnetically confined fusion, astrophysical plasms, fundamental atomic data and advanced modeling and plasma diagnostics, where international researchers share cutting-edge results in plasma creation, plasma experiments and plasma modeling.
Abstract: The Atomic Processes in Plasmas Conference is a bi-annual international conference on topics covering high-energy-density plasmas, magnetically confined fusion plasmas, astrophysical plasmas, fundamental atomic data and advanced modeling and plasma diagnostics. The conference lets international researchers share cutting-edge results in plasma creation, plasma experiments and plasma modeling.
770 citations
TL;DR: In this paper, the analysis of noise and vibration signals is presented. But the authors focus on a case study of pipe flow noise and vibrations and use it as a diagnostic tool.
Abstract: Preface Acknowledgements Introductory comments 1. Mechanical vibrations: a review of some fundamentals 2. Sound waves: a review of some fundamentals 3. Interactions between sound waves and solid structures 4. Noise and vibration measurement and control procedures 5. The analysis of noise and vibration signals 6. Statistical energy analysis of noise and vibration 7. Pipe flow noise and vibration: a case study 8. Noise and vibration as a diagnostic tool 9. Worked examples Appendices Problems Answers to problems Index.
648 citations
TL;DR: In this paper, a method and system for communicating audio signals between an input device and an output device via a network is presented, where the output device can include loudspeakers and headphones.
Abstract: A method and system for communicating audio signals between an input device and an output device via a network. The output device can include loudspeakers and headphones. In some embodiments an output device, for example a center channel speaker, transmits audio signals to other output devices. In some embodiments, the output device is coupled to, or combined with, a speaker stand or speaker bracket. The network can be wireless, wired, infrared, RF, and powerline.
593 citations
TL;DR: The acoustic properties of the skull can be deduced from high resolution CT scans and used to achieve a noninvasive adaptive focusing, which could have promising applications in brain tumor hyperthermia but also in transcranial ultrasonic imaging.
Abstract: Developing minimally invasive brain surgery by high-intensity focused ultrasound beams is of great interest in cancer therapy. However, the skull induces strong aberrations both in phase and amplitude, resulting in a severe degradation of the beam shape. Thus, an efficient brain tumor therapy would require an adaptive focusing, taking into account the effects of the skull. In this paper, we will show that the acoustic properties of the skull can be deduced from high resolution CT scans and used to achieve a noninvasive adaptive focusing. Simulations have been performed with a full 3-D finite differences code, taking into account all the heterogeneities inside the skull. The set of signals to be emitted in order to focus through the skull can thus be computed. The complete adaptive focusing procedure based on prior CT scans has been experimentally validated. This could have promising applications in brain tumor hyperthermia but also in transcranial ultrasonic imaging.
475 citations
TL;DR: Findings shed light on the nature of the talker-listener interaction during speech communication and show speech from a relatively high proficiency non-native talker from the same native language background was as intelligible asspeech from a native talker, giving rise to the "matched interlanguage speech intelligibility benefit".
Abstract: This study investigated how native language background influences the intelligibility of speech by non-native talkers for non-native listeners from either the same or a different native language background as the talker. Native talkers of Chinese (n=2), Korean (n=2), and English (n=1) were recorded reading simple English sentences. Native listeners of English (n=21), Chinese (n=21), Korean (n=10), and a mixed group from various native language backgrounds (n=12) then performed a sentence recognition task with the recordings from the five talkers. Results showed that for native English listeners, the native English talker was most intelligible. However, for non-native listeners, speech from a relatively high proficiency non-native talker from the same native language background was as intelligible as speech from a native talker, giving rise to the “matched interlanguage speech intelligibility benefit.” Furthermore, this interlanguage intelligibility benefit extended to the situation where the non-native talker and listeners came from different language backgrounds, giving rise to the “mismatched interlanguage speech intelligibility benefit.” These findings shed light on the nature of the talker–listener interaction during speech communication.
472 citations
TL;DR: Five bilateral cochlear implant users were tested for their localization abilities and speech understanding in noise, and participated in lateralization tasks to assess the impact of variations in interaural time delays (ITDs) and Interaural level differences (ILDs) for electrical pulse trains under direct computer control.
Abstract: Five bilateral cochlear implant users were tested for their localization abilities and speech understanding in noise, for both monaural and binaural listening conditions. They also participated in lateralization tasks to assess the impact of variations in interaural time delays (ITDs) and interaural level differences (ILDs) for electrical pulse trains under direct computer control. The localization task used pink noise bursts presented from an eight-loudspeaker array spanning an arc of approximately 108° in front of the listeners at ear level (0-degree elevation). Subjects showed large benefits from bilateral device use compared to either side alone. Typical root-mean-square (rms) averaged errors across all eight loudspeakers in the array were about 10° for bilateral device use and ranged from 20° to 60° using either ear alone. Speech reception thresholds (SRTs) were measured for sentences presented from directly in front of the listeners (0°) in spectrally matching speech-weighted noise at either 0°, +90° or −90° for four subjects out of five tested who could perform the task. For noise to either side, bilateral device use showed a substantial benefit over unilateral device use when noise was ipsilateral to the unilateral device. This was primarily because of monaural head-shadow effects, which resulted in robust SRT improvements (P<0.001) of about 4 to 5 dB when ipsilateral and contralateral noise positions were compared. The additional benefit of using both ears compared to the shadowed ear (i.e., binaural unmasking) was only 1 or 2 dB and less robust (P=0.04). Results from the lateralization studies showed consistently good sensitivity to ILDs; better than the smallest level adjustment available in the implants (0.17 dB) for some subjects. Sensitivity to ITDs was moderate on the other hand, typically of the order of 100 μs. ITD sensitivity deteriorated rapidly when stimulation rates for unmodulated pulse-trains increased above a few hundred Hz but at 800 pps showed sensitivity comparable to 50-pps pulse-trains when a 50-Hz modulation was applied. In our opinion, these results clearly demonstrate important benefits are available from bilateral implantation, both for localizing sounds (in quiet) and for listening in noise when signal and noise sources are spatially separated. The data do indicate, however, that effects of interaural timing cues are weaker than those from interaural level cues and according to our psychophysical findings rely on the availability of low-rate information below a few hundred Hz.
460 citations
TL;DR: It is shown how to create synthetic sounds with first and second order envelope statistics identical to those found in natural sounds, and postulated that the auditory system as well as engineering applications may exploit these statistical properties to obtain an efficient representation of behaviorally relevant sounds.
Abstract: The modulation statistics of natural sound ensembles were analyzed by calculating the probability distributions of the amplitude envelope of the sounds and their time-frequency correlations given by the modulation spectra. These modulation spectra were obtained by calculating the two-dimensional Fourier transform of the autocorrelation matrix of the sound stimulus in its spectrographic representation. Since temporal bandwidth and spectral bandwidth are conjugate variables, it is shown that the joint modulation spectrum of sound occupies a restricted space: sounds cannot have rapid temporal and spectral modulations simultaneously. Within this restricted space, it is shown that natural sounds have a characteristic signature. Natural sounds, in general, are low-passed, showing most of their modulation energy for low temporal and spectral modulations. Animal vocalizations and human speech are further characterized by the fact that most of the spectral modulation power is found only for low temporal modulation. Similarly, the distribution of the amplitude envelopes also exhibits characteristic shapes for natural sounds, reflecting the high probability of epochs with no sound, systematic differences across frequencies, and a relatively uniform distribution for the log of the amplitudes for vocalizations. It is postulated that the auditory system as well as engineering applications may exploit these statistical properties to obtain an efficient representation of behaviorally relevant sounds. To test such a hypothesis we show how to create synthetic sounds with first and second order envelope statistics identical to those found in natural sounds.
439 citations
TL;DR: In this article, a Graphical User Interface (GUI) for an ultrasound system has been presented, which provides several types of graphical elements with intelligent behavior such as being context sensitive and adaptive, called active objects, for example, tabs, menus, icons, windows of user interaction and data display and an alphanumeric keyboard.
Abstract: A Graphical User Interface (GUI) for an ultrasound system. The ultrasound system has operational modes and the GUI has corresponding icons, tabs, and menu items image and information fields. The User Interface (UI) provides several types of graphical elements with intelligent behavior, such as being context sensitive and adaptive, called active objects, for example, tabs, menus, icons, windows of user interaction and data display and an alphanumeric keyboard. In addition the UI may also be voice activated. The UI further provides for a touchscreen for direct selection of displayed active objects. In an embodiment, the UI is for a medical ultrasound handheld imaging instrument. The UI provides a limited set of hard and soft keys with adaptive functionality that can be used with only one hand and potentially with only one thumb.
429 citations
TL;DR: In this article, a power transmission system using directional ultrasound for power transmission includes a transmitting device and a receiving device, where the transmitting device has a set of ultrasound transducers forming an ultrasound transducer array.
Abstract: A power transmission system using directional ultrasound for power transmission includes a transmitting device and a receiving device. The transmitting device has a set of ultrasound transducers forming an ultrasound transducer array, wherein the array is a set of spaced individual transducers placed in the X-Y plane disposed to generate an ultrasound beam in the Z direction.
427 citations
TL;DR: In this article, a system, method, and business model for an information system and service having business self-promotion, promotion and promotion tracking, loyalty or frequent participant rewards and redemption, audio coupon, ratings, and other features.
Abstract: The invention provides a system, method, and business model for an information system and service having business self-promotion, promotion and promotion tracking, loyalty or frequent participant rewards and redemption, audio coupon, ratings, and other features. A business or organization in which consumers call into a service using ordinary telephone, PC, PDA, or other information appliance, and make requests in plain speech for information on goods and/or services, and the service provides responses to the request in plain speech in real-time. Provides operating model for a telephone-based audio-interfaced goods and services information and referral service having merchant self-promotion features, including database provider storing merchant information; an interface for inputting merchant information into the database and for retrieving and editing the information; and an interface for inputting voice commands and data and for receiving merchant information and processed information from the database in response to the input voice commands and data.
418 citations
TL;DR: The results suggest that using steady-state noise to test speech intelligibility may underestimate the difficulties experienced by cochlear-implant users in fluctuating acoustic backgrounds.
Abstract: This study investigated the effects of simulated cochlear-implant processing on speech reception in a variety of complex masking situations. Speech recognition was measured as a function of target-to-masker ratio, processing condition (4, 8, 24 channels, and unprocessed) and masker type (speech-shaped noise, amplitude-modulated speech-shaped noise, single male talker, and single female talker). The results showed that simulated implant processing was more detrimental to speech reception in fluctuating interference than in steady-state noise. Performance in the 24-channel processing condition was substantially poorer than in the unprocessed condition, despite the comparable representation of the spectral envelope. The detrimental effects of simulated implant processing in fluctuating maskers, even with large numbers of channels, may be due to the reduction in the pitch cues used in sound source segregation, which are normally carried by the peripherally resolved low-frequency harmonics and the temporal fine structure. The results suggest that using steady-state noise to test speech intelligibility may underestimate the difficulties experienced by cochlear-implant users in fluctuating acoustic backgrounds.
TL;DR: This study investigates which factors affect the forms of function words, especially whether they have a fuller pronunciation or a more reduced or lenited pronunciation, based on over 8000 occurrences of the ten most frequent English function words in a 4-h sample from conversations from the Switchboard corpus.
Abstract: Function words, especially frequently occurring ones such as (the, that, and, and of ), vary widely in pronunciation. Understanding this variation is essential both for cognitive modeling of lexical production and for computer speech recognition and synthesis. This study investigates which factors affect the forms of function words, especially whether they have a fuller pronunciation (e.g., ði, ðaet, aend, ʌv) or a more reduced or lenited pronunciation (e.g., ðə, ðīt, n, ə). It is based on over 8000 occurrences of the ten most frequent English function words in a 4-h sample from conversations from the Switchboard corpus. Ordinary linear and logistic regression models were used to examine variation in the length of the words, in the form of their vowel (basic, full, or reduced), and whether final obstruents were present or not. For all these measures, after controlling for segmental context, rate of speech, and other important factors, there are strong independent effects that made high-frequency monosyllabic function words more likely to be longer or have a fuller form (1) when neighboring disfluencies (such as filled pauses uh and um) indicate that the speaker was encountering problems in planning the utterance; (2) when the word is unexpected, i.e., less predictable in context; (3) when the word is either utterance initial or utterance final. Looking at the phenomenon in a different way, frequent function words are more likely to be shorter and to have less-full forms in fluent speech, in predictable positions or multiword collocations, and utterance internally. Also considered are other factors such as sex (women are more likely to use fuller forms, even after controlling for rate of speech, for example), and some of the differences among the ten function words in their response to the factors.
TL;DR: In this paper, the authors proposed a supervised learning approach to speech segregation, in which a target speech signal is separated from interfering sounds using spatial localization cues: interaural time differences (ITD) and intra-aural intensity differences (IID).
Abstract: At a cocktail party, one can selectively attend to a single voice and filter out all the other acoustical interferences. How to simulate this perceptual ability remains a great challenge. This paper describes a novel, supervised learning approach to speech segregation, in which a target speech signal is separated from interfering sounds using spatial localization cues: interaural time differences (ITD) and interaural intensity differences (IID). Motivated by the auditory masking effect, the notion of an "ideal" time-frequency binary mask is suggested, which selects the target if it is stronger than the interference in a local time-frequency (T-F) unit. It is observed that within a narrow frequency band, modifications to the relative strength of the target source with respect to the interference trigger systematic changes for estimated ITD and IID. For a given spatial configuration, this interaction produces characteristic clustering in the binaural feature space. Consequently, pattern classification is performed in order to estimate ideal binary masks. A systematic evaluation in terms of signal-to-noise ratio as well as automatic speech recognition performance shows that the resulting system produces masks very close to ideal binary ones. A quantitative comparison shows that the model yields significant improvement in performance over an existing approach. Furthermore, under certain conditions the model produces large speech intelligibility improvements with normal listeners.
TL;DR: In this article, a system for the destruction of adipose tissue utilizing high intensity focused ultrasound (HIFU) within a patient's body is presented, which comprises a controller for data storage and the operation and control of a plurality of elements.
Abstract: A system for the destruction of adipose tissue utilizing high intensity focused ultrasound (HIFU) within a patient's body. The system comprises a controller for data storage and the operation and control of a plurality of elements. One elements is a means for mapping a human body to establish three dimensional coordinate position data for existing adipose tissue. The controller is able to identify the plurality of adipose tissue locations on said human body and establish a protocol for the destruction of the adipose tissue. A HIFU transducer assembly having one or more piezoelectric element(s) is used along with at least one sensor wherein the sensor provides feed back information to the controller for the safe operation of the piezoelectric element(s). The sensor is electronically coupled to the controller, and the controller provides essential treatment command information to one or more piezoelectric element(s) based on positioning information obtained from the three dimensional coordinate position data.
TL;DR: It is shown here that the ears of fish exposed to an operating air-gun sustained extensive damage to their sensory epithelia that was apparent as ablated hair cells.
Abstract: Marine petroleum exploration involves the repetitive use of high-energy noise sources, air-guns, that produce a short, sharp, low-frequency sound. Despite reports of behavioral responses of fishes and marine mammals to such noise, it is not known whether exposure to air-guns has the potential to damage the ears of aquatic vertebrates. It is shown here that the ears of fish exposed to an operating air-gun sustained extensive damage to their sensory epithelia that was apparent as ablated hair cells. The damage was regionally severe, with no evidence of repair or replacement of damaged sensory cells up to 58 days after air-gun exposure.
TL;DR: The possibility of recovering the Green’s function from the field-field correlations of coda waves in an open multiple scattering medium is investigated, based on fundamental symmetries of reciprocity, time-reversal invariance, and the Helmholtz–Kirchhoff theorem.
Abstract: The possibility of recovering the Green’s function from the field-field correlations of coda waves in an open multiple scattering medium is investigated. The argument is based on fundamental symmetries of reciprocity, time-reversal invariance, and the Helmholtz–Kirchhoff theorem. A criterion is defined, indicating how sources should be placed inside an open medium in order to recover the Green’s function between two passive receivers. The case of noise sources is also discussed. Numerical experiments of ultrasonic wave propagation in a multiple scattering medium are presented to support the argument.
Rohm1
TL;DR: In this article, a bias acceleration circuit for rapidly increasing the magnitude of a bias voltage in time can be provided in or with the bias circuit, whereby even in case of the capacitance of the capacitor included in bias circuit being increased for improving the power supply rejection ratio (PSRR), the rise in the bias voltage can be increased so that the pop sound which arises when bias circuit is activated can be still diminished.
Abstract: the output amplifiers requiring a bias voltage can be activated or deactivated individually, and a bias acceleration circuit for rapidly increasing the magnitude of a bias voltage in time can be provided in or with the bias circuit, whereby even in case of the capacitance of the capacitor included in the bias circuit being increased for improving the power supply rejection ratio (PSRR), the rise in the bias voltage can be increased so that the pop sound which arises when the bias circuit is activated can be still diminished.
TL;DR: A wearable wireless audio device includes a support, an electronics circuit, and a speaker as mentioned in this paper, which is configured to convert the audio signal into sound and rotate along an axis substantially parallel to a z-axis with respect to the support.
Abstract: A wearable wireless audio device includes a support, an electronics circuit, and a speaker. The support includes a first ear stem and an orbital, and is configured to support at least one lens in a wearer's field of view. The electronics circuit is supported by the support and is configured to receive at least one digital audio file and generate an audio signal indicative of the at least one digital audio file. The speaker is supported by the support, and is directed toward at least one of the wearer's ears. The speaker is configured to convert the audio signal into sound. The speaker has a speaker face, and the speaker is configured to rotate from a first position in which the speaker face is substantially parallel to a yz-plane to a second position in which the speaker is inclined at an angle with respect to the yz-plane. The speaker is coupled to the support with a speaker pivot, and is configured to rotate about the speaker pivot while maintaining the speaker face substantially parallel to a yz-plane. The speaker is configured to move along an axis substantially parallel to a z-axis with respect to the support.
TL;DR: In this article, the transducer array is disposed within a liquid-filled elastomeric material that more effectively couples ultrasound energy into the tumor, that is directly contacted with the device.
Abstract: An ultrasound system used for both imaging and delivery high intensity ultrasound energy therapy to treatment sites and a method for treating tumors and other undesired tissue within a patient's body with an ultrasound device. The ultrasound device has an ultrasound transducer array disposed on a distal end of an elongate, relatively thin shaft. In one form of the invention, the transducer array is disposed within a liquid-filled elastomeric material that more effectively couples ultrasound energy into the tumor, that is directly contacted with the device. Using the device in a continuous wave mode, a necrotic zone of tissue having a desired size and shape (e.g., a necrotic volume selected to interrupt a blood supply to a tumor) can be created by controlling at least one of the f-number, duration, intensity, and direction of the ultrasound energy administered. This method speeds the therapy and avoids continuously pausing to enable intervening normal tissue to cool.
TL;DR: Evaluated cochlear implant users' ability to understand sentences in the presence of modulated speech-shaped noise suggested that normal-hearing listeners obtain significant release from masking from modulated maskers, especially at 8-Hz masker modulation frequency.
Abstract: Many competing noises in real environments are modulated or fluctuating in level. Listeners with normal hearing are able to take advantage of temporal gaps in fluctuating maskers. Listeners with sensorineural hearing loss show less benefit from modulated maskers. Cochlear implant users may be more adversely affected by modulated maskers because of their limited spectral resolution and by their reliance on envelope-based signal-processing strategies of implant processors. The current study evaluated cochlear implant users’ ability to understand sentences in the presence of modulated speech-shaped noise. Normal-hearing listeners served as a comparison group. Listeners repeated IEEE sentences in quiet, steady noise, and modulated noise maskers. Maskers were presented at varying signal-to-noise ratios (SNRs) at six modulation rates varying from 1 to 32 Hz. Results suggested that normal-hearing listeners obtain significant release from masking from modulated maskers, especially at 8-Hz masker modulation frequency. In contrast, cochlear implant users experience very little release from masking from modulated maskers. The data suggest, in fact, that they may show negative effects of modulated maskers at syllabic modulation rates (2–4 Hz). Similar patterns of results were obtained from implant listeners using three different devices with different speech-processor strategies. The lack of release from masking occurs in implant listeners independent of their device characteristics, and may be attributable to the nature of implant processing strategies and/or the lack of spectral detail in processed stimuli.
TL;DR: In this letter, consideration is given to the problems of defining IM and specifying research that is needed to better understand and model IM.
Abstract: Informational masking (IM) has a long history and is currently receiving considerable attention. Nevertheless, there is no clear and generally accepted picture of how IM should be defined, and once defined, explained. In this letter, consideration is given to the problems of defining IM and specifying research that is needed to better understand and model IM.
TL;DR: This study uses spiral k-space acquisitions with a low flip-angle gradient echo pulse sequence on a conventional GE Signa 1.5-T CV/i scanner to examine the dynamics of vocal-tract shaping during fluent speech using MRI.
Abstract: Magnetic resonance imaging (MRI) has served as a valuable tool for studying static postures in speech production. Now, recent improvements in temporal resolution are making it possible to examine the dynamics of vocal-tract shaping during fluent speech using MRI. The present study uses spiral k-space acquisitions with a low flip-angle gradient echo pulse sequence on a conventional GE Signa 1.5-T CV/i scanner. This strategy allows for acquisition rates of 8-9 images per second and reconstruction rates of 20-24 images per second, making veridical movies of speech production now possible. Segmental durations, positions, and interarticulator timing can all be quantitatively evaluated. Data show clear real-time movements of the lips, tongue, and velum. Sample movies and data analysis strategies are presented.
TL;DR: Identification of trainees' post-test tone productions improved by 18% relative to their pretest productions, indicating significant tone production improvement after perceptual training, and acoustic analyses of the pre- and post-training productions reveal the nature of the improvement.
Abstract: Training American listeners to perceive Mandarin tones has been shown to be effective, with trainees' identification improving by 21%. Improvement also generalized to new stimuli and new talkers, and was retained when tested six months after training [Y. Wang et al., J. Acoust. Soc. Am. 106, 3649-3658 (1999)]. The present study investigates whether the tone contrasts gained perceptually transferred to production. Before their perception pretest and after their post-test, the trainees were recorded producing a list of Mandarin words. Their productions were first judged by native Mandarin listeners in an identification task. Identification of trainees' post-test tone productions improved by 18% relative to their pretest productions, indicating significant tone production improvement after perceptual training. Acoustic analyses of the pre- and post-training productions further reveal the nature of the improvement, showing that post-training tone contours approximate native norms to a greater degree than pretraining tone contours. Furthermore, pitch height and pitch contour are not mastered in parallel, with the former being more resistant to improvement than the latter. These results are discussed in terms of the relationship between non-native tone perception and production as well as learning at the suprasegmental level.
TL;DR: On-axis click properties support previous work proposing the nose of sperm whales to operate as a generator of sound.
Abstract: Traditionally, sperm whale clicks have been described as multipulsed, long duration, nondirectional signals of moderate intensity and with a spectrum peaking below 10 kHz. Such properties are counterindicative of a sonar function, and quite different from the properties of dolphin sonar clicks. Here, data are presented suggesting that the traditional view of sperm whale clicks is incomplete and derived from off-axis recordings of a highly directional source. A limited number of assumed on-axis clicks were recorded and found to be essentially monopulsed clicks, with durations of 100 micros, with a composite directionality index of 27 dB, with source levels up to 236 dB re: 1 microPa (rms), and with centroid frequencies of 15 kHz. Such clicks meet the requirements for long-range biosonar purposes. Data were obtained with a large-aperture, GPS-synchronized array in July 2000 in the Bleik Canyon off Vesteralen, Norway (69 degrees 28' N, 15 degrees 40' E). A total of 14 h of sound recordings was collected from five to ten independent, simultaneously operating recording units. The sound levels measured make sperm whale clicks by far the loudest of sounds recorded from any biological source. On-axis click properties support previous work proposing the nose of sperm whales to operate as a generator of sound.
TL;DR: The speech intelligibility test results confirm the importance of early reflections for achieving good conditions for speech in rooms and show that for common conditions where the direct sound is reduced, it is only possible to understand speech because of the presence ofEarly reflections.
Abstract: This paper presents the results of new studies based on speech intelligibility tests in simulated sound fields and analyses of impulse response measurements in rooms used for speech communication. The speech intelligibility test results confirm the importance of early reflections for achieving good conditions for speech in rooms. The addition of early reflections increased the effective signal-to-noise ratio and related speech intelligibility scores for both impaired and nonimpaired listeners. The new results also show that for common conditions where the direct sound is reduced, it is only possible to understand speech because of the presence of early reflections. Analyses of measured impulse responses in rooms intended for speech show that early reflections can increase the effective signal-to-noise ratio by up to 9 dB. A room acoustics computer model is used to demonstrate that the relative importance of early reflections can be influenced by the room acoustics design.
TL;DR: In this article, a catheter is provided for insertion in the heath vessel of a patient for ultrasonically imaging the vessel wall, which includes a tubular element and an internally housed drive cable.
Abstract: A catheter is provided for insertion in the he blood vessel of a patient for ultrasonically imaging the vessel wall. The catheter includes a tubular element and an internally housed drive cable for effective circumferential scan about the catheter of an ultrasonic generating means. Both the tubular element and the drive cable are of a size and flexibility sufficient to permit their introduction into the vessel and subsequent advancement through the vessel to the location of the vessel wall where imaging is desired.
TL;DR: A quantitative study of the reflection of the T(0,1) mode from defects in pipes in the frequency range 10-300 kHz has been carried out, finite element predictions being validated by experiments on selected cases.
Abstract: A quantitative study of the reflection of the T(0,1) mode from defects in pipes in the frequency range 10-300 kHz has been carried out, finite element predictions being validated by experiments on selected cases. Both cracklike defects with zero axial extent and notches with varying axial extents have been considered. The results show that the reflection coefficient from axisymmetric cracks increases monotonically with depth at all frequencies and increases with frequency at any given depth. In the frequency range of interest there is no mode conversion at axisymmetric defects. With nonaxisymmetric cracks, the reflection coefficient is a roughly linear function of the circumferential extent of the defect at relatively high frequencies, the reflection coefficient at low circumferential extents falling below the linear prediction at lower frequencies. With nonaxisymmetric defects, mode conversion to the F(1,2) mode is generally seen, and at lower frequencies the F(1,3) mode is also produced. The depth and circumferential extent are the parameters controlling the reflection from cracks; when notches having finite axial extent, rather than cracks, are considered, interference between the reflections from the start and the end of the notch causes a periodic variation of the reflection coefficient as a function of the axial extent of the notch. The results have been explained in terms of the wave-number-defect size product, ka. Low frequency scattering behavior is seen when ka 1.
TL;DR: Results in vivo on man biceps shows the existence of slow and fast shear waves as predicted by theory, and the evidence of the polarization of low frequency shear strain waves is supported by both numeric simulations and experiments.
Abstract: From the measurement of a low frequency (50–150 Hz) shear wave speed, transient elastography evaluates the Young’s modulus in isotropic soft tissues. In this paper, it is shown that a rod source can generate a low frequency polarized shear strain waves. Consequently this technique allows to study anisotropic medium such as muscle. The evidence of the polarization of low frequency shear strain waves is supported by both numeric simulations and experiments. The numeric simulations are based on theoretical Green’s functions in isotropic and anisotropic media (hexagonal system). The experiments in vitro led on beef muscle proves the pertinent of this simple anisotropic pattern. Results in vivo on man biceps shows the existence of slow and fast shear waves as predicted by theory.
TL;DR: In this paper, an energy harvesting device with structural members covered with piezoelectric material resonating at different primary frequencies is described. But, the structure to which the device is secured vibrates over a range of frequencies, and more than one member resonates or is close to resonance.
Abstract: An energy harvesting device is provided. The energy harvesting device includes structural members covered with piezoelectric material resonating at different primary frequencies. As the structure to which the energy harvesting device is secured vibrates over a range of frequencies, more than one member resonates or is close to resonance. As such, multiple members work simultaneously to create electrical energy.
AT&T1
TL;DR: In this article, a method for constructing an efficient concatenation cost database is provided by synthesizing a large body of speech, identifying the acoustic unit sequential pairs generated and their respective concatenations, and storing those concatenated costs likely to occur.
Abstract: A speech synthesis system can select recorded speech fragments, or acoustic units, from a very large database of acoustic units to produce artificial speech. The selected acoustic units are chosen to minimize a combination of target and concatenation costs for a given sentence. However, as concatenation costs, which are measures of the mismatch between sequential pairs of acoustic units, are expensive to compute, processing can be greatly reduced by pre-computing and caching the concatenation costs. Unfortunately, the number of possible sequential pairs of acoustic units makes such caching prohibitive. However, statistical experiments reveal that while about 85% of the acoustic units are typically used in common speech, less than 1% of the possible sequential pairs of acoustic units occur in practice. A method for constructing an efficient concatenation cost database is provided by synthesizing a large body of speech, identifying the acoustic unit sequential pairs generated and their respective concatenation costs, and storing those concatenation costs likely to occur. By constructing a concatenation cost database in this fashion, the processing power required at run-time is greatly reduced with negligible effect on speech quality.