Frequency modulation improves sensitivity to interaural timing differences at high frequencies in the presence of noise

2018 ◽  
Vol 143 (3) ◽  
pp. 1945-1945
Author(s):  
Alan Kan
Keyword(s):  
Frequency Modulation ◽  
High Frequencies

scholarly journals Is the Frequency Content of the Calls in North American Treefrogs Limited by Their Larynges?

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Marcos Gridi-Papp
Keyword(s):  
Frequency Modulation ◽  
Sound Intensity ◽  
Frequency Content ◽  
Frequency Range ◽  
Low Frequencies ◽  
High Frequencies ◽  
Mating Calls ◽  
Limited Frequency ◽  
Positive Direct ◽  
High Diversity

A high diversity of mating calls is found among frogs. The calls of most species, however, are simple, in comparison to those of mammals and birds. In order to determine if the mechanics of the larynx could explain the simplicity of treefrog calls, the larynges of euthanized males were activated with airflow. Laryngeal airflow, sound frequency, and sound intensity showed a positive direct relationship with the driving air pressure. While the natural calls of the studied species exhibit minimal frequency modulation, their larynges produced about an octave of frequency modulation in response to varying pulmonary pressure. Natural advertisement calls are produced near the higher extreme of frequency obtained in the laboratory and at a slightly higher intensity (6 dB). Natural calls also exhibit fewer harmonics than artificial ones, because the larynges were activated with the mouth of the animal open. The results revealed that treefrog larynges allow them to produce calls spanning a much greater range of frequencies than observed in nature; therefore, the simplicity of the calls is not due to a limited frequency range of laryngeal output. Low frequencies are produced at low intensities, however, and this could explain why treefrogs concentrate their calling at the high frequencies.

The stability of Poiseuille flow modulated at high frequencies

1975 ◽  
Vol 344 (1639) ◽  
pp. 453-464 ◽  
Keyword(s):  
Frequency Modulation ◽  
Poiseuille Flow ◽  
High Frequency ◽  
Parallel Flow ◽  
Plane Poiseuille Flow ◽  
High Frequencies ◽  
The Stability

The effect of high frequency modulation on the stability of plane Poiseuille flow is considered. It is shown how the stability characteristics of this flow can be completely determined from those of the unmodulated flow. It is found that modulation destabilizes the flow. The method can be used to investigate the stability of any parallel or nearly parallel flow modulated at high frequencies.

scholarly journals Evolution of acoustic communication in crickets: phylogeny of Eneopterinae reveals an adaptive radiation involving high-frequency calling (Orthoptera, Grylloidea, Eneopteridae)

2004 ◽  
Vol 76 (2) ◽  
pp. 297-300 ◽  
Author(s):  
Tony Robillard ◽  
Laure Desutter-Grandcolas
Keyword(s):  
Acoustic Communication ◽  
Frequency Modulation ◽  
Adaptive Radiation ◽  
High Frequency ◽  
Ancestral State ◽  
High Frequencies ◽  
Dominant Frequencies

Evolution of dominant frequencies in songs of Eneopterinae crickets was studied with respect to phylogeny. Two characters are optimized on the tree: the first describes the frequency resulting from the vibration of the harp (Fda), and the second is due to the vibration of other tegminal areas (Fdb). Fda was found to be relatively stable through the subfamily. Its low ancestral state is replaced by a high Fda only once, resulting in high-frequency calling in [Cardiodactylus (Lebinthus-Agnotecous)]. A high Fdb component is added to the low ancestral Fda in Eneoptera guyanensis, resulting in frequency modulation. The onset of high Fd in this first subclade is accompanied by a high cladogenesis rate, which supports a hypothesis of adaptive radiation for high frequencies. The effectiveness of high-frequency calling is discussed in relation to the species behavior ecology.

Quasi-Periodic Oscillations in Dwarf Novae

1979 ◽  
Vol 46 ◽  
pp. 77-88
Author(s):  
Edward L. Robinson
Keyword(s):  
Binary Systems ◽  
Outer Edge ◽  
Light Curves ◽  
Close Binary ◽  
Bright Spot ◽  
Dwarf Novae ◽  
Periodic Oscillations ◽  
High Frequencies ◽  
Short Period ◽  
Typical Time

Three distinct kinds of rapid variations have been detected in the light curves of dwarf novae: rapid flickering, short period coherent oscillations, and quasi-periodic oscillations. The rapid flickering is seen in the light curves of most, if not all, dwarf novae, and is especially apparent during minimum light between eruptions. The flickering has a typical time scale of a few minutes or less and a typical amplitude of about .1 mag. The flickering is completely random and unpredictable; the power spectrum of flickering shows only a slow decrease from low to high frequencies. The observations of U Gem by Warner and Nather (1971) showed conclusively that most of the flickering is produced by variations in the luminosity of the bright spot near the outer edge of the accretion disk around the white dwarf in these close binary systems.

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