Sound Recording Solutions
Sound Card Recorder
Powerful voice activated microphone recorder for Windows. Click here to learn more.Stereophonic Sound
Stereophonic sound, commonly called stereo, is the reproduction of sound, using two independent audio channels, through a pair of widely separated speaker systems, in such a way as to create a pleasant and natural impression of sound heard from various directions as in natural hearing. It is often opposed to mono, where audio is in the form of one channel, often centered in the sound field. The word "stereophonic", from Greek stereos = "solid" and phone = "sound", was coined by Western Electric, by analogy with the word "stereoscopic". Western Electric first demonstrated it at an SMPTE meeting in 1937, then to the general public at Carnegie Hall in 1940. In popular usage, stereo usually means 2-channel sound recording and sound reproduction using data for more than one speaker simultaneously. In technical usage, stereo or stereophony means sound recording and sound reproduction that uses stereographic projection to encode the relative positions of objects and events recorded. A stereo system can include any number of channels, such as the multichannel audio 5.1- and 6.1-channel systems used on high-end film and television productions. However, it more commonly means only two-channel systems. The electronic device for playing back stereo sound is often called "a stereo". Stereo is derived from the term stereographic projection, which here generates a stereo image during playback. During two-channel stereo recording, two microphones are placed in strategic locations in relation to the source, both record at once. Each channel will be similar, but each will have distinct time-of-arrival difference and sound pressure level difference information. On playback, the listener's brain uses the subtle differences in timing and level to triangulate the positions of the recorded objects. Stereo recordings often cannot be played by monaural systems without a significant loss of fidelity. Since each microphone records each wavefront at a slightly different time, constructive and destructive interference can occur, if both tracks are played on the same speaker. This phenomenon is known as comb filtering. Here there are two directional microphones at the same place, and typically pointing at an angle 90ø or more to each other - see also "The Stereophonic Zoom" by Michael Williams. A stereo effect is achieved through differences in sound pressure level between two microphone. Due to the lack of differences in time-of-arrival/phase-ambiguities, the sonic characteristic of X-Y recordings is generally less spacy and has less depth compared to recordings employing an AB-setup. When the microphones are bidirectional and placed facing +-45ø with respect to the sound source the X-Y-setup is called a Blumlein Pair. The sonic image produced by this configuration is considered by many authorities to create a most realistic, almost holographic soundstage. Intensity stereo is an unfortunate linguistic misnomer which has come to mean the recording of stereophonic signals that are distinguished only by level differences. These "level differences" have been called "intensity" differences, but sound intensity is a specifically defined quantity and cannot be sensed by a simple microphone, nor would it be valuable in music recording if it could. Like microphones our ear drums are sensitive only to the sound pressure. This uses two parallel omnidirectional microphones some distance apart, so capturing time-of-arrival stereo information as well as some level (amplitude) difference information, especially if employed in close proximity to the sound source(s). At a distance of 51.5 cm the time delay for a signal reaching first one and then the other microphone from the side is approximately 1.5 msec. According to Eberhard Sengpiel this is enough to locate the sound source exactly at the speaker on the respective side, resulting in a stereophonic pickup angle of 180ø. If you increase the distance between the microphones you effectively decrease the pickup angle. At 70 cm distance it is about equivalent to the pickup angle of the near-coincident ORTF-setup. This coincident technique employs a bidirectional microphone facing sideways and another (of any characteristic; Alan Blumlein described the usage of an omnidirectional transducer in his original patent) at an angle of 90ø facing the sound source. The Left and right channels are produced through a simple matrix: Left = Mid + Side, Right = Mid - Side (the phase-inverted side-signal). This configuration produces a complety mono-compatible signal, the width of which can be manipulated after the recording has taken place, which makes it especially useful for the usage on film-based projects. Engineers make a technical distinction between "binaural" and "stereophonic" recording. Of these, binaural recording is more like stereoscopic photography. In binaural recording, a pair of microphones is put inside a model of a human head which includes external ears and ear canals. Each microphone is where the eardrum would be. The recording is then played back through headphones, so that each channel is presented independently, without mixing or crosstalk. Thus, each of the listener's eardrums is driven with a replica of the auditory signal it would have experienced at the recording location. The result is an accurate duplication of the auditory spatiality that would have been heard by the listener placed where the microphones were. Because of the nuisance of wearing headphones, true binaural recordings have remained laboratory and audiophile curiosities. Stereophonic sound attempts to create an illusion of location for various instruments within the original recording. The recording engineer's goal is usually to create a stereo "image" with localization information. When a stereophonic recording is heard through loudspeaker systems rather than headphones, each ear of course hears sound from both speakers. The audio engineer may and often does use more than two microphones, sometimes many more, and may mix them down to two tracks in ways that exaggerate the separation of the instruments to compensate for the mixture that occurs when listening via speakers. Descriptions of stereophonic sound tend to stress the ability to localize the position of each instrument in space, but in reality many people listen on playback systems that do a poor job of re-creating a stereo "image". Many listeners assume that "stereo" sound is "richer" or "fuller-sounding" than monophonic sound. This is inaccurate - stereo and mono can have equally detailed abilities to play recorded notes. The spatial illusion is what sets stereo recordings apart from mono recordings. When playing back stereo recordings, best results are obtained by using two speakers, in front of and equidistant from the listener, with the listener located on the center line between the two speakers. In common usage, a "stereo" is a two-channel sound reproduction system, and a "stereo recording" is a two-channel recording. This is a cause for much confusion, since five (or more) channel home theater systems are not popularly described as "stereo". It is worth noting that most film soundtracks are not recorded using stereo techniques, so while capable of stereo playback, most home theater systems rarely do. Most two-channel recordings are stereo recordings only in this weaker sense. Pop music, in particular, is usually recorded using close miking techniques, which artificially separates signals into several tracks. The separate tracks are then mixed into a two-channel recording which often bears little or no resemblance to the actual physical and spatial relationship of the musicians at the time of the original performance. Indeed, it is not uncommon for different tracks of the same song to be recorded at different times, and even in different studios, and then mixed into a final two-channel recording for commercial release. Classical music recordings are a notable exception.
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