acoustic spectrum


  • WordNet 3.6
    • n acoustic spectrum the distribution of energy as a function of frequency for a particular sound source
    • ***


In news:

With an emphasis on acoustic guitar-driven songs, Jeff Parets presents the full spectrum of acoustic rock, including rarely heard "unplugged" versions of classic tunes in their purest form.

In science:

At a plasma frequency of ∼ 60 kHz taken from the dynamic spectrum, the ion plasma frequency, where the ion acoustic wave branch flattens out, is between 1 and 2 kHz which corresponds to the intense red line at the bottom of the dynamic spectrum.
Fundamentals of Non-relativistic Collisionless Shock Physics: IV. Quasi-Parallel Supercritical Shocks
There would then not be any acoustic peaks in the anisotropy spectrum of the CMB – in contrast to observation! The fundamental questions of the quantum-to-classical transition have thus observational relevance.
Why do cosmological perturbations look classical to us?
On sub-degree scales, the rich structure in the anisotropy spectrum is the consequence of gravity-driven acoustic oscillations occurring before the atoms in the Universe became neutral.
Cosmic Microwave Background Mini-review
This picture has received further confirmation with the detection in the power spectrum of galaxies (at redshifts close to zero) of the imprint of these same acoustic oscillations in the baryon component [28,29,30].
Cosmic Microwave Background Mini-review
Baryon acoustic oscillations (BAOs) imprinted in the galaxy power spectrum can be used as a standard ruler to determine angular diameter distance and Hubble parameter at high redshift galaxies.
Forecasting the Cosmological Constraints with Anisotropic Baryon Acoustic Oscillations from Multipole Expansion
The distance between collisions Λ, with respect to the radiation wavelength λ, determines the narrowing factor. A movie clip in the Supplementary Material illustrates the DopplerDicke transition in the acoustic spectrum of a moving emitter, obtained numerically by following Dicke (1953).
Coherent Diffusion of Polaritons in Atomic Media
In this Letter, we probe the nature of the fluctuations through CMB anisotropy observations of the acoustic signatures in the spectrum.
A New Test of Inflation
Short-wavelength fluctuations which enter the horizon while the universe is radiation-dominated oscillate as acoustic waves of constant amplitude and are damped by photon diffusion, transferring energy from the acoustic waves to the CMB spectrum and creating a non-zero chemical potential , .
The Cosmic Microwave Background Spectrum
Hu and White have argued that all inflationary models produce an angular power spectrum with a unique set of “doppler” or “acoustic” peaks between ℓ = 100 and ℓ = 1000 (11′ < θ < 1.8◦ ).
The Cosmic Microwave Background Anisotropy Experiments
While on large angular scales the predicted CMBR spectrum is in good agreement with COBE measurements, on smaller angular scales the topological defects models cannot reproduce the data of the Saskatoon experiment, namely the characteristics of the first acoustic peak.
Cosmic Microwave Background Anisotropies: Inflation versus Topological Defects
The authors deduced that the absence of significant acoustic peaks in the CMBR anisotropy spectrum is a robust result for all models with global textures, as well as the large-N limit of O(N ) models, for all considered choices of cosmological parameters 27 .
Cosmic Microwave Background Anisotropies: Inflation versus Topological Defects
The source depth for high frequency oscillations ( ν > 5.5 mHz, the acoustic cutoff in the solar atmosphere) can be obtained from the frequency separation between adjacent peaks in the power spectrum.
Source depth for solar p-modes
The power spectrum of p-modes below the acoustic cut-off frequency of ∼ 5.5mHz is distinctly asymmetric and the magnitude of asymmetry is a function of source depth which has been used by Abrams & Kumar (1996) and Kumar & Basu (1999b) to determine the source depth for low frequency modes.
Source depth for solar p-modes
Their effects can be observed as the shifts of the location and the height of the acoustic peak in the CMB spectrum.
Bulk Gravitational Field and Cosmological Perturbations on the Brane
These deviations can be directly observed as the shifts of the location and height of the peak of the acoustic oscillation in CMB spectrum.
Bulk Gravitational Field and Cosmological Perturbations on the Brane