Typically low-level electrical distortions and interference created in an electronic component from power supply hum, interactions between internal electrical components, etc. Noise may also be in the form of radio waves or other distractions from the pure signal transference, modification or amplification. oise is found in all electrical components. Digital devices such as CD players and DVD players tend to suffer from less noise than analog devices such as turntables and audiocassette players. Additionally, solid state electronics are less plagued by noise problems than vacuum tube-based components. he lower the noise rating of a component the better. Noise is typically not a problem with audio and video reproduction until one wants to play soft music or attain enhanced detail. At some point, the signal actually is lower in power than the noise itself (the noise floor), resulting in the true signal being obscured and lost due to noise. The lower the noise level of a component, the smaller a signal the component can cleanly produce and the more detail the component may have at low levels. o experience system noise, turn on an audio system and turn the volume all the way down so no signal is being output. Place your ear close to the speaker and listen closely. The hissing, incoherent sound you hear is noise in your system. High-quality systems will have less noise and others may have great deals of noise. The lower the noise, the better. hen looking for an audio/video component, pay attention to the signal-to-noise ratio to determine the amount of noise in the component. The S/N ratio (signal-to-noise ratio) is measured in decibels (dB) and the larger the S/N number the better. It is the difference between the maximum signal output of a device and its noise level or noise floor. A S/N ratio of 100 dB means that the maximum signal is 100 dB louder or more powerful than the noise of the component or device. Noise should be minimized when possible, but at sufficiently high S/N ratios (of 80 to 90 dB or so) it is of less importance than at lower levels. Noise is an important factor in purchasing an audio/video component and should be taken into account with other criteria to make an informed purchase decision.