Sound Recording Solutions
Sound Card Recorder
Powerful voice activated microphone recorder for Windows. Click here to learn more.White Noise
White noise is a random signal (or process) with a flat power spectral density. In other words, the signal's power spectral density has equal power in any band, at any centre frequency, having a given bandwidth. White noise is so called as an analogy with white light which contains all frequencies. An infinite-bandwidth white noise signal is purely a theoretical construct. By having power at all frequencies, the total power of such a signal is infinite. In practice, a signal can be "white" with a flat spectrum over a defined frequency band. The term white noise is also commonly applied to a noise signal in the spatial domain which has zero autocorrelation over the relevant space dimensions. The signal is then "white" in the spatial frequency domain (this is equally true for signals in the angular frequency domain, e.g. the distribution of a signal across all angles in the night sky). The image to the right displays a finite length, discrete time realization of a white noise process generated from a computer. Being uncorrelated in time does not, however, restrict the values a signal can take. Any distribution of values is possible (although it must have zero DC component). For example, a binary signal which can only take on the values 1 or 0 will be white if the sequence of zeros and ones is statistically uncorrelated. Noise having a continuous distribution, such as a normal distribution, can of course be white. It is often incorrectly assumed that Gaussian noise (i.e. noise with a Gaussian amplitude distribution - see normal distribution) is necessarily white noise. However, neither property implies the other. Gaussianity refers to the way signal values are distributed, while the term 'white' refers to correlations at two distinct times, which are independent of the noise amplitude distribution. We can therefore find Gaussian white noise, but also Poisson, Cauchy, etc. white noises. Note that the distribution must have infinite variance. Thus, the two words "Gaussian" and "white" are often both specified in mathematical models of systems. Gaussian white noise is a good approximation of many real-world situations and generates mathematically tractable models. These models are used so frequently that the term additive white Gaussian noise has a standard abbreviation: AWGN. Gaussian white noise has the useful statistical property that its values are independent (see Statistical independence). White noise is the generalized mean-square derivative of the Wiener process or Brownian motion. One use for white noise is in the field of architectural acoustics. Here in order to submerge distracting, undesirable noises (for example conversations, etc.) in interior spaces, a constant low level of noise is generated and provided as a background sound. White noise is used by some sirens for emergency vehicles, due to its ability to cut through background noise (e.g. urban traffic noise). White noise has also been used in electronic music, where it is used either directly or as an input for a filter to create other types of noise signal. It is used extensively in audio synthesis, typically to recreate percussive instruments such as cymbals which have high noise content in their frequency domain. It is also used to generate impulse responses. To set up the EQ for a concert or other performance in a venue, a short burst of pink noise is sent through the PA system and monitored from various points in the venue so that the engineer can tell if the acoustics of the building naturally boost or cut any frequencies. He or she can then adjust the overall EQ to ensure a balanced mix. White noise is used as the basis of some random number generators. White noise can be used to disorient individuals prior to interrogation and may be used as part of sensory deprivation techniques. White noise machines are sold as privacy enhancers and sleep aids.
Phone Call Recorder
Must have software for voice modem. Record all phone calls automatically, watch Caller ID information, create you own powerful answering machine. Perfect sound quality. Click here to learn more.3d audio effect - 3gp - a-law - aac - acm - adc - aiff - aliasing - amplifier - amr-wb - amr-wb plus - amr - apev2 tag - asf - atrac - audio codec - audio compression - avi - bitrate - bitrate peeling - chord - codec - comfort noise - compact audio cassette - compact disc - compression - compression artifact - compression ratio - contact microphone - container format - dab - data compression - digital audio - digital camera - divx - dolby digital - dolby digital plus - dsp - dvd-audio - dvd - effects unit - equalization - ffmpeg - flanging - fourcc - frequency spectrum - hi-fi - high-end audio - hiln - id3 - joint stereo - laser microphone - line level - lossy - loudspeaker - matroska - mcf - microphone - midi - mixing console - mp2 - mp3 - mp3 surround - mp3 sx - mp3pro - mp4 - mpeg-1 - mpeg-21 - mpeg-3 - mpeg-4 - mpeg-7 - mpeg - mu-law - musepack - music - mxf - nut - osm - parabolic microphone - pcm - perception - phonograph - pink noise - pqf - psychoacoustics - qdesign - quadraphonic - radio receiver - ratdvd - realaudio - red noise - reverberation - rhythm - ribbon microphone - riff - rmvb - sbr - signal processing - sound - sound card - sound effects - sound recording - spdif - speech encoding - speech recognition - speex - stereo - subwoofer - surround sound - synthesizer - tape recorder - tdm - tweeter - video - video compression - vob - voice analysis - vorbis - wav - white noise - wma - woofer