White Noise

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White Noise

The audio equivalent of Brownian motion. Sounds that are unrelated and sound like a hiss. The video equivalent of white noise is "snow" in television reception.
Copyright © 2012, Campbell R. Harvey. All Rights Reserved.

Random Walk Theory

An investment philosophy holding that security prices are completely unpredictable, especially in the short term. Random walk theory states that both fundamental analysis and technical analysis are wastes of time, as securities behave randomly. Thus, the theory holds that it is impossible to outperform the market by choosing the "correct" securities; it is only possible to outperform the market by taking on additional risk. Critics of random walk theory contend that empirical evidence shows that security prices do indeed follow particular trends that can be predicted with a fair degree of accuracy. The theory originated in 1973 with the book, A Random Walk Down Wall Street. See also: Efficient markets theory.
Farlex Financial Dictionary. © 2012 Farlex, Inc. All Rights Reserved
References in periodicals archive ?
Caption: Figure 2: (a) Top panel shows white noise with 500 sample points; Middle panel shows the MSE for various time series (TS) lengths; bottom panel shows normalized MSE (for scale factors [tau] = 1, 2, 3, and 5) and SE; (b) top panel shows pink noise with 500 sample points; middle panel shows the MSE for various time series (TS) lengths; bottom panel shows normalized MSE (for scale factors [tau] = 1, 2, 3, and 5) and SE; (c) top panel shows brown noise with 500 sample points; middle panel shows the MSE for various time series (TS) lengths; bottom panel shows normalized MSE (for scale factors [tau] = 1,2,3, and 5) and SE.
The sounds used were a combination of white and pink noise in varying proportions--the same encoding used for the game described in the previous section.
The experiment showed that within the corpus of the research material pink noise provides better protection of the utterance than white noise at equal integral level of signal-to-noise ratio (for all tested levels) in terms of the following indicators: detection of speech signal in noise (see Figure 1), correct identification of the utterance language (see Figure 2), and correct perception of the semantic content of the utterance.
Consequently, this type of pink noise modulation is excellent for local heating (other important effects of pink noise modulation are discussed elsewhere [11]).
With babble noise, the mean durations over 61 subjects were 143, ms (SD 37 ms) and 349 ms (SD 76 ms), and correspondingly with pink noise, 130 ms (SD 32 ms) and 341 ms (SD 79 ms).
(21) Input = 1 + STEP (step height, step time)+ (pulse quantity/TIME STEP)\times PULSE (pulse time, TIME STEP)+ RAMP (ramp slope, ramp start time, ramp end time) + sine amplitude \ times SIN (2 \times 3.14159 \times time/sine period) + STEP (1, noise start time) \times pink noise Units: dimensionless
(4) For an analysis of Pink Noise, see my essay "Toward a Poetics of Noise: From Hu Shi to Hsia Yii," Chinese Literature: Essays, Articles, Reviews 30 (2008), 167-78.
Industrial noise, generated broadband noises (e.g., white or pink noise), tonal sounds, road traffic, and jet engines primarily increase catecholamine levels, such as norepinephrine, and corticosteroids, such as cortisol.
To measure the noise isolation properties of the earphones, the test chamber was filled with non-correlated pink noise. A measurement of that noise was taken directly by HATS with no headset.
Four types of additive noises were used: white noise, pink noise, factory noise (plate-cutting and electrical welding equipment) and F16 cockpit noise selected from Noisex-92 database [15].
First impressions were of high transparency and clarity, and as I walked about listening to de-correlated pink noise to optimize placement, I was struck by the complete lack of coloration as I moved up and down, side to side, and all around.