Studies of horizontal refraction and scattering of low‐frequency acoustic signals using a modal approach in signal processing of NPAL data

2003 ◽  
Vol 113 (4) ◽  
pp. 2333-2333
Author(s):  
Alexander G. Voronovich ◽  
Vladimir E. Ostashev ◽  
Keyword(s):  
Signal Processing ◽  
Low Frequency ◽  
Acoustic Signals ◽  
Modal Approach ◽  
Horizontal Refraction

Fish Attraction with Pulsed Low-Frequency Sound

1968 ◽  
Vol 25 (7) ◽  
pp. 1441-1452 ◽  
Author(s):  
Joseph D. Richard
Keyword(s):  
Acoustic Stimulus ◽  
Low Frequency ◽  
Reef Fishes ◽  
Test Site ◽  
Acoustic Signals ◽  
Commercial Fisheries ◽  
Test Results ◽  
Potential Applications ◽  
Predatory Fishes ◽  
Underwater Television

A series of tests were conducted to determine the effectiveness of pulsed low-frequency acoustic signals for attracting fishes. The acoustic signals were contrived to simulate the hydrodynamically generated disturbances normally associated with active predation. Underwater television was used to observe fish arrivals during both control and test periods. Demersal predatory fishes were successfully attracted although they habituated rapidly to the acoustic stimulus. Members of the families Serranidae, Lutjanidae, and Pomadasyidae were particularly well represented among the fishes attracted. Sharks were also attracted in considerable numbers. Herbivorous reef fishes, although common around the test site, were not attracted. Possible relationships between the test results and the hearing capabilities of fishes are discussed. It is concluded that acoustic attraction techniques have potential applications in certain existing commercial fisheries.

scholarly journals Speech Identification with Temporal and Spectral Modification in Subjects with Auditory Neuropathy

2012 ◽  
Vol 2012 ◽  
pp. 1-7
Author(s):  
Vijaya Kumar Name ◽  
C. S. Vanaja
Keyword(s):  
Signal Processing ◽  
Speech Processing ◽  
Word Identification ◽  
Low Frequency ◽  
Auditory Neuropathy ◽  
Study Word ◽  
Spectral Modification ◽  
The Individual ◽  
High Pass ◽  
Speech Identification

Background. The aim of this study was to investigate the individual effects of envelope enhancement and high-pass filtering (500 Hz) on word identification scores in quiet for individuals with Auditory Neuropathy. Method. Twelve individuals with Auditory Neuropathy (six males and six females) with ages ranging from 12 to 40 years participated in the study. Word identification was assessed using bi-syllabic words in each of three speech processing conditions: unprocessed, envelope-enhanced, and high-pass filtered. All signal processing was carried out using MATLAB-7. Results. Word identification scores showed a mean improvement of 18% with envelope enhanced versus unprocessed speech. No significant improvement was observed with high-pass filtered versus unprocessed speech. Conclusion. These results suggest that the compression/expansion signal processing strategy enhances speech identification scores—at least for mild and moderately impaired individuals with AN. In contrast, simple high-pass filtering (i.e., eliminating the low-frequency content of the signal) does not improve speech perception in quiet for individuals with Auditory Neuropathy.

scholarly journals Non-destructive ultrasonic tomography for concrete pavement evaluation: signal processing and image analysis of crucial parameters

2017 ◽  
Vol 10 (6) ◽  
pp. 1182-1191
Author(s):  
L. S. SALLES ◽  
J. T. BALBO ◽  
L. KHAZANOVICH
Keyword(s):  
Signal Processing ◽  
Concrete Slab ◽  
Low Frequency ◽  
Concrete Pavement ◽  
Ultrasonic Tomography ◽  
Transverse Cracks ◽  
Pavement Maintenance ◽  
Use Of Technology ◽  
Pavement Evaluation ◽  
Non Destructive

Abstract In recent years, due to the destructive and unproductive character of pavement specimen extraction, pavement maintenance technology intensified the use of non-destructive techniques for pavement evaluation which resulted in the development of several devices and evaluation methods. This paper describes the use of technology based on low frequency ultrasonic tomography for evaluation of concrete pavement parameters. The equipment was applied in three experimental sections with different concrete pavements built at the University of Sao Paulo campus. The ultrasonic signal processing is given. The results analysis enables the efficient and reliable identification of thickness and reinforcement position within the concrete slab. Construction problems were evidenced in one of experimental sections with thickness deficiencies and reinforcement in a position below projected. Furthermore, the use of a novel concrete quality indicator was correlated with the presence of transverse cracks and alkali-silica reaction within the sections.

A High Efficient Baseband GNSS Signal Narrow Band Anti-Jamming Approach in Frequency Domain

2014 ◽  
Vol 926-930 ◽  
pp. 1857-1860
Author(s):  
Zhou Zheng ◽  
Meng Yuan Li ◽  
Wei Jiang Wang
Keyword(s):  
Signal Processing ◽  
Frequency Domain ◽  
Narrow Band ◽  
Low Frequency ◽  
Frequency Resolution ◽  
Interference Rejection ◽  
High Efficient ◽  
Digital Down Conversion ◽  
Down Conversion ◽  
Low Rate

In order to reduce the burden of the calculation and the low frequency resolution of the tradition GNSS signal intermediate narrow band anti-jamming method, it introduces a high efficient approach of narrow band interference rejection based on baseband GNSS signal processing. After digital down conversion to baseband and down sampling to a low rate, the interference is removed in frequency domain. According to the theoretical analysis and simulation, it claims that the method can reduce the calculation and increase the detection resolution in frequency domain which will realize a high efficient interference rejection.

scholarly journals Acoustic Signal Attenuation Determination Technique Traveling Through Obstacles

2019 ◽  
Vol 8 (3) ◽  
pp. 2012-2016
Keyword(s):  
Signal Processing ◽  
Acoustic Signal ◽  
Acoustic Signals ◽  
Signal Frequency ◽  
Signal Attenuation ◽  
Laboratory Procedure ◽  
Novel Technique ◽  
Sonar Signal Processing ◽  
Launch Angle

This paper presents a novel technique for calculation of attenuation of acoustic signals in the materials in underwater channel. A laboratory procedure and algorithms have been developed for finding attenuation. In many applications like sonar signal processing acoustic signal attenuation in the dome or in an enclosure are required to be known. Finding the actual attenuation while signal passes through the materials is very useful in calculating the precise power transmitted through the enclosures. The attenuation in materials mainly dependent on type of material, signal frequency and launch angle of the signal. A proper procedure has been presented in this paper

Coherence of low‐frequency acoustic signals in the deep ocean

1974 ◽  
Vol 56 (4) ◽  
pp. 1122-1125 ◽  
Author(s):  
J. D. Shaffer ◽  
R. M. Fitzgerald ◽  
A. N. Guthrie
Keyword(s):  
Low Frequency ◽  
Deep Ocean ◽  
Acoustic Signals
Sign in / Sign up

Export Citation Format

Share Document