Search results
Results from the WOW.Com Content Network
Electronic noise management test in Vienna, 1973. The first patent for a noise control system— U.S. patent 2,043,416 —was granted to inventor Paul Lueg in 1936. The patent described how to cancel sinusoidal tones in ducts by phase-advancing the wave and canceling arbitrary sounds in the region around a loudspeaker by inverting the polarity. [3]
The internal electronic circuitry of an active noise-canceling mic attempts to subtract noise signal from the primary microphone. The circuit may employ passive or active noise canceling techniques to filter out the noise, producing an output signal that has a lower noise floor and a higher signal-to-noise ratio.
For example, CD audio uses 16 bits per sample, and therefore it will have quantization noise approximately 96 dB below the maximum possible sound pressure level (when summed over the full bandwidth) The amount of space required to store PCM depends on the number of bits per sample, the number of samples per second, and the number of channels.
Adaptive feedback cancellation originated during the evolution of the hearing aid. The hearing aid became digital, and as such feedback cancellation was needed. In 1980 a directional microphone was introduced in the digital hearing aid, and adaptive feedback cancellation was created to block external noise that the microphone picked up. Today ...
Noise reduction is the process of removing noise from a signal. Noise reduction techniques exist for audio and images. Noise reduction algorithms may distort the signal to some degree. Noise rejection is the ability of a circuit to isolate an undesired signal component from the desired signal component, as with common-mode rejection ratio.
Most external microphone designs are of either omnidirectional or noise-canceling type. Noise-canceling microphone headsets use a bi-directional microphone as elements. A bi-directional microphone's receptive field has two angles only. Its receptive field is limited to only the front and the direct opposite back of the microphone.
Adaptive noise cancelling is a signal processing technique that is highly effective in suppressing additive interference or noise corrupting a received target signal at the main or primary sensor in certain common situations where the interference is known and is accessible but unavoidable and where the target signal and the interference are unrelated, that is, uncorrelated [1] [2] [3].
A microphone’s sensitivity varies with frequency (as well as with other factors such as environmental conditions) and is therefore normally recorded as several sensitivity values, each for a specific frequency band (see frequency spectrum). A microphone’s sensitivity can also depend on the nature of the sound field it is exposed to.