摘要:

Over the past several years, many groups have been carrying out research in the area of fiber optic sensor technology, and many types of fiber sensors have been developed. Two of the most promising fiber optic sensor types will be discussed in this talk: phase‐modulated single mode interferometric sensors and intensity modulated multimode fiber sensors. Phase‐modulated sensors, which utilize an all fiber Mach‐Zehnder interferometer, have high sensitivity and geometric versatility. Since the phase sensitivity of a fiber depends primarily on its coating, different fiber coatings can be utilized to detect various physical perturbations, such as acoustic, magnetic, electric, and thermal. The intensity modulated sensor is based on microbending losses which depend on the amplitude of the bend of a multimode fiber. The microbend sensor has moderate sensitivity, simple optical and electronic construction, and utilizes available multimode technology. If the fiber deformer mechanical design is tailored to a given external perturbation, various fields, such as acoustic, pressure, acceleration, and magnetic can be detected. In this talk, the transduction mechanism of each sensor type will be discussed and mechanical designs for detecting various fields will be presented.

ISSN:0001-4966    

DOI:10.1121/1.2021899

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

Recent technology advances in thin film deposition and in fabrication of Si microstructures have made possible the development of a new class of “intelligent” sensors having electronics and sensing element integrated on the same Si chip. The present paper describes a fully integrated microphone which combines high sensitivity, wide frequency range, low power, and low cost of batch processed miniature silicon components. A thin piezoelectric layer of ZnO transforms the mechanical deflection of a thin Si diaphragm into a piezoelectric output voltage. This signal is directly connected to an amplifier built on the same chip. A unique annular electrode design provides cancellation of temperature induced parasitic signal due to the pyroelectric effect in ZnO. Integrated devices were fabricated and tested. Measured performances were: sensitivity of 25 μV/μbar, a signal to noise ratio of 5:1 at 2 μbars, a frequency response of 0.1 Hz to 10 kHz and a power consumption below 40 μW. Further improvements in the onchip electronics should increase the signal to noise ratio by an order of magnitude bringing its value in the range of the conventional hearing aid devices.

ISSN:0001-4966    

DOI:10.1121/1.2021900

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

To insure efficient utilization of the system, space station design and operations will require special habitability considerations for the occupants and crew because of the relatively long duration missions. Of particular concern is the environment in which the personnel will live and work, and how it affects both the performance and comfort of the occupants. Current criteria do not consider possible effects of reduced gravity, long duration, and confinement. Preliminary to developing space station vibroacoustic habitability criteria, the adequacy of criteria for other space vehicles has been reviewed. In this paper, specific responses to the noise and vibration environments of both Skylab and Shuttle will be discussed. Some astronauts have reported sleep interference, communication interference, distraction, and general annoyance as noise related complaints. In addition, information from the Russian Salyut missions, as well as similar earth based situations (e.g., submarines, remote military outposts), will be reviewed.

ISSN:0001-4966    

DOI:10.1121/1.2021905

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

Using an exact solution for scatter from a pressure release sinusoidal surface, the unknown surface velocity distribution from plane‐wave excitation can be computed. Comparisons are presented between this solution and the velocity distribution predicted by the Kirchhoff approximation (both with and without consideration of shadowing) with grazing angle as a parameter. The effects of surface shadowing are shown and the nature of the difference between the solutions is investigated. Surprisingly, the Kirchhoff approximation gives good results for the reflection coefficient at very low grazing angles; however, the reason for this agreement is fortuitous. A diffractive shadowing correction to be the Kirchhoff approximation is examined and is shown to yield little improvement.

ISSN:0001-4966    

DOI:10.1121/1.2021909

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

Results from low‐grazing‐angle surface forward‐scattering measurements made in the open ocean at 15–40 kHz will be presented. The data were obtained with broad beam transducers using 1.0‐and 0.3‐ms pulses. The data have been analyzed to obtain energy losses and pulse elongations associated with the surface interaction at several wind speeds. The implications of the measured losses in terms of near‐surface bubble populations will be discussed. [Work supported by NAVSEA.]

ISSN:0001-4966    

DOI:10.1121/1.2021915

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

Acoustical responses acquired in a scale model have been used to produce audible simulations for subjective evaluation of architectural conditions. A spark source excites the model, and the response of a miniature microphone is sampled by a microcomputer‐based data acquisition system. The model response so obtained is deconvolved by using “pseudo‐SVD” pseudoinverse filtering developed by Walsh and Ulrych. This deconvolution technique circumvents, in an optimal manner, the “whitening” effect of previously available methods. The resulting impulse response is reconvolved with anechoically recorded music to yield an audible simulation of the conditions being investigated. As an example, the use of this technique in the acoustical design of a concert hall is discussed. Here a 1:24 scale model was used in the study of the subjective effect of diffraction from a large architectural grille. The early portions of the model impulse responses collected with and without the grille were convolved with anechoically recorded music. Comparison of these audibly demonstrated the coloration introduced by the grille.

ISSN:0001-4966    

DOI:10.1121/1.2021920

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

EMG studies of speech production have most commonly used either a configuration in which the electrodes were inserted with the interelectrode axis parallel to that of the muscle fibers, or the Basmajian and Stecko configuration [J. Appl. Physiol.17,849 (1962)] in which the electrodes are offset across the cross section of the muscle. In a differential recording configuration the first procedure results in analog differencing of a single longitudinally propagating signal at a time lag determined by the interelectrode distance and the mean propagation velocity of the action potentials. The second procedure results in differencing of two different signals. Assuming again that the electrode insertions are parallel, in the Basmajian and Stecko procedure the relation between the two signals differenced depends both on the longitudinal separation of the electrodes and on their separation in two dimensions across the muscle cross section. The resulting waveform and spectral characteristics of the signals from the two types of insertions necessarily differ. Detailed effects depend on the size of the motor units and distribution of their fibers, interelectrode distance, and patterns of motor unit recruitment.

ISSN:0001-4966    

DOI:10.1121/1.2021922

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

The effects of high‐intensity auditory maskers on whistling and voicing pitch matching tasks were studied. Subjects whistled or produced the vowel /ah/ to match the frequency of a target tone. Nine experimental masking conditions were presented randomly: no masker, white noise, a pure tone at the target frequency, three tones above and three tones below the target frequency. Masker tones were presented at either 80 or 100 dB SPL. Mean fundamental frequency of voicing was essentially unaffected by auditory manipulations, i.e., productions obtained during masking conditions were no different than productions in quiet. For whistling, mean fundamental frequency of production appeared to be differentially affected by masker frequency. Masker frequencies lower than the target generally resulted in higher frequency of production. Similar effects were observed for both levels of masking stimuli which argues against an interpretation of the observed effects in terms of a peripheral masking of the production. Rather, we would suggest that the results are consistent with a hypothesis that the behaviors involved in the whistling and voicing tasks are differentially affected by auditory information. [Work supported by NIH Grant 07555.]

ISSN:0001-4966    

DOI:10.1121/1.2021929

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

The Blom‐Singer voice prosthesis and tracheostomal valve for voice restoration following laryngectomy promised improved communication ease, quality, and flexibility over traditional esophageal speech. Increased use of T‐E puncture at time of laryngectomy, effectively precludes learning standard esophageal speech, even for patients holding promise of speech independent of prosthetic devices. The assumption is that the B‐S prosthesis with the T‐S valve is superior to esophageal speech because: (1) speech becomes lung powered, (2) hand manipulation is unneeded, and (3) voice quality is more “normal.” This present study investigated (1) phonation onset latency, (2) intercostal muscle mistiming of syllables, (3) intensity of voice, and (4) phonetic accuracy of initial consonants in connected speech in two speech production modes (B‐S plus T‐S valve versus B‐S plus manual occlusion of stoma) in one patient who underwent total laryngectomy with B‐S and T‐S valve placement. The investigation suggested (1) there is phonation latency with T‐S valve use, (2) latency affects syllable timing of initial consonant production, (3) voice intensity is greater with manual occlusion than with T‐S use, and (4) phonetic accuracy is enhanced in the manual occlusion mode as opposed to the T‐S mode. T‐S valve use was associated with a sacrifice of voice quality and loudness suggesting that laryngectomy patients be allowed a six‐month period to learn traditional esophageal speech before a T‐E puncture is made and the B‐S apparatus is utilized.

ISSN:0001-4966    

DOI:10.1121/1.2021936

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

Hearing‐impaired listeners have problems in understanding speech, especially in noisy conditions. Since speech is a fluctuating signal, it is of interest to investigate the relation between the perception of speech and of stimuli fluctuating in time. We measured the continuity threshold for bursts of pure tones alternated with noise bursts [denoted as the pulsation threshold by Houtgast (thesis, Amsterdam, 1974)] in a group of 20 hearing‐impaired and 10 normal‐hearing subjects. The tone‐noise period varied from 100 to 800 ms and the tone level from 10 to 80 dB above hearing threshold. A special measuring technique made it possible to obtain highly consistent and reliable results. The results show that there is an effect of fusion of discontinuous signals. For the normal‐hearing subjects the continuity threshold drops to lower tone‐burst levels for longer tone‐noise periods. For the hearing‐impaired listeners this phenomenon is even stronger. The range of the transition between the perception of continuity and of discontinuity is larger for the hearing‐impaired than for the normal‐hearing listeners. We also found some relations with other auditory functions measured. [Work supported by ZWO.]

ISSN:0001-4966    

DOI:10.1121/1.2021938

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP