Narrow band high frequency clicks from Hourglass dolphins (Lagenorhynchus cruciger)

2008 ◽  
Vol 123 (5) ◽  
pp. 3363-3363
Author(s):  
Line A. Kyhn ◽  
Jakob Tougaard ◽  
Magnus Wahlberg ◽  
Kristian Beedholm ◽  
Peter T. Madsen
Keyword(s):  
High Frequency ◽  
Narrow Band ◽  
Lagenorhynchus Cruciger

scholarly journals Propagation of narrow-band-high-frequency clicks: Measured and modeled transmission loss of porpoise-like clicks in porpoise habitats

2010 ◽  
Vol 127 (1) ◽  
pp. 560-567 ◽  
Author(s):  
Stacy L. DeRuiter ◽  
Michael Hansen ◽  
Heather N. Koopman ◽  
Andrew J. Westgate ◽  
Peter L. Tyack ◽  
...  
Keyword(s):  
High Frequency ◽  
Transmission Loss ◽  
Narrow Band

Disparity Modulation Sensitivity for Narrow-Band-Filtered Stereograms Viewed out of the Plane of Fixation

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 94-94
Author(s):  
B Lee ◽  
B J Rogers
Keyword(s):  
Spatial Frequency ◽  
High Frequency ◽  
Significant Interaction ◽  
Narrow Band ◽  
Low Frequency ◽  
Frequency Pattern ◽  
Spatial Frequencies ◽  
Size Disparity ◽  
Random Dot Stereograms

Narrow-band-filtered random-dot stereograms were used to determine stereo thresholds for detecting sinusoidal disparity modulations. These stereograms were designed to stimulate selectively channels tuned to luminance and corrugation spatial frequencies (Schumer and Ganz, 1979 Vision Research19 1303 – 1314). Thresholds were determined for corrugation frequencies ranging from 0.125 to 1 cycle deg−1, luminance centre spatial frequencies ranging from 1 to 8 cycles deg−1 and disparity pedestal sizes ranging from −32 to +32 min arc. For small disparity pedestals, lowest modulation thresholds were found around 0.5 cycle deg−1 corrugation frequency and 4 cycles deg−1 luminance centre spatial frequency. For large disparity pedestals (±32 arc min), lowest thresholds were shifted towards the lower corrugation frequencies (0.125 cycle deg−1) and lower luminance frequencies (2 cycles deg−1). There was a significant interaction between luminance spatial frequency and disparity pedestal size. For small pedestals, lowest thresholds were found with the highest luminance frequency pattern (4 cycles deg−1). For large pedestals, best performance shifted towards the low-frequency patterns (1 cycle deg−1). This effect demonstrates a massive reduction in stereo-efficiency for high-frequency patterns in the luminance domain at large disparity pedestals which is consistent with the ‘size-disparity relation’ proposed by previous researchers.

scholarly journals Raising your voice: evolution of narrow-band high-frequency signals in toothed whales (Odontoceti)

2018 ◽  
Vol 126 (2) ◽  
pp. 213-224 ◽  
Author(s):  
Anders Galatius ◽  
Morten Tange Olsen ◽  
Mette Elstrup Steeman ◽  
Rachel A Racicot ◽  
Catherine D Bradshaw ◽  
...  
Keyword(s):  
High Frequency ◽  
Narrow Band

Reduction of Vibration and Noise Generated by Planetary Ring Gears in Helicopter Aircraft Transmissions

1973 ◽  
Vol 95 (4) ◽  
pp. 1149-1158 ◽  
Author(s):  
Thomas Chiang ◽  
R. H. Badgley
Keyword(s):  
High Frequency ◽  
Narrow Band ◽  
Vibration Energy ◽  
Ring Gear ◽  
Noise Sources ◽  
Rotor Drive ◽  
Design Changes ◽  
Planetary Ring ◽  
Gear Meshes ◽  
Very High

Rotor-drive gearboxes are major noise sources in helicopter aircraft. Narrow-band examination of this noise often indicates the presence of several or more very high, narrow noise peaks, which are located at gearbox mesh frequencies or their multiples. Important exceptions are sideband noise components, located so near the main signal component as to be indistinguishable except by very narrow band reduction. Noise of this type is most effectively treated through a systematic study of the flow of high-frequency vibration energy in the drive train. Such studies should examine the mechanism by which gear meshes generate vibrations, and the vibration response of the gearbox components which support the gears. Results of such calculations are presented for the planetary reduction ring-gear casing elements in the Boeing-Vertol CH-47 forward rotor-drive gearbox and the Bell UH-1D main rotor-drive gearbox. The calculations indicate logical reasons why noise is generated. Typical ring-gear casing design changes are examined for noise reduction.

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