Surround sound is the name for a spatial sound impression in sound recordings (English: ambience). In a broader sense, theatrical performances can also be included that convey a spatial sound experience.
The first room sound music was produced by several orchestras or choirs that were placed in different places in the room (see Venetian multi-choirs ). Giovanni Gabrieli was a master of this art, Johann Sebastian Bach used this technique for example. B. in his St. Matthew Passion .
In the 1950s, stereophony was developed - the recording of music with two equivalent sound channels, absolutely synchronous , developed in parallel for the electrical / electronic sound recording process and sound transmission process with record , radio and tape in approximately the same sound quality, which allows left-right localization in the Playback through stereo speakers enabled. Recording processes in transit time stereophony, and less so in intensity stereophony, enable the sound source to be localized in depth, which is referred to as depth graduation .
Artificial head stereophony
A further development to improve the spatial impression of the sound is the artificial head stereophony or headphone stereophony , which is intended solely for headphone reproduction. It is on an artificial head, for. B. made of plastic , in particular simulated the anatomy of the ears . High -quality microphones with omnidirectional characteristics are used in these , which record the sound environment around the entire head , but above all with the auricles and less that of the auditory canal . For concert recordings , even for large orchestras , a single artificial head is used without additional microphones. The sound recordings can only be played back via headphones and not only gives a left-right impression, but also an up-down and front-back impression. In the music sector, artificial head stereophony has not caught on, but numerous radio plays are produced in which the possibilities of 3-D room localization are used in a targeted manner. There are problems with the direct front localization .
Ambiophony is an extension of stereophony in which additional surround sound is reproduced either via discrete channels or as an admixture to the stereo signal (stereo ambiophony). This serves to reinforce the spatial impression. The sound components are recorded using additional room microphones, which are usually placed somewhat away from the main sound source.
In lecture or performance rooms, special ambiophony systems that u. a. create targeted reverberation, a room acoustics are greatly improved.
An extension of the stereophony was the quadrophony , in which four sound channels were recorded synchronously, with the additional two channels mainly containing the sound reflections and room signals of the recording room. However, this procedure did not catch on because the additional information was too little. The matrixing also degraded the sound. Especially in the radio technology was for the extra effort with transmitter encoding and receiver-side decoding, for the introduction of FM -Stereofonie gained some experience, seen no corresponding added value. Marketing remained limited to the sound carrier record , for which pickups with frequency ranges from 20 Hz to 50 kHz were developed (CD-4).
Use in music
The first protagonists of music for spatial sound are Stockhausen (e.g. Gruppen (1955) or Carree (1959)), Edgar Varèse (“poeme electronique”, 1958) and Pink Floyd (e.g. Ummagumma , 1969).
Under surround sound , the movement and placement is of sound sources in the room by means of several speakers understood as "surround sound". In the SWR experimental studio , a special matrix (halaphone) was developed through which the movement and placement of sounds can be controlled very precisely. With the digitization of sound processing , many other institutes developed tools for spatialization (spatialization) of sounds. Software can be found u. a. also in the Ircam forum .
The processes licensed by Dolby under the names Dolby Digital 5.1 , 7.1 or Dolby Surround are interesting in terms of effects for the cinema , but less suitable for the reproduction of specific surround-sound music. Surround sound requires equal treatment of all spatial directions, while the playback systems that were developed for cinemas, such as Dolby Digital, SDDS , DTS , etc., are always oriented towards the optical center point , i.e. towards the screen, towards the front. With Dolby Virtual Speaker , the company has developed a system for simulating surround sound from just one source (e.g. for headphones).
The EAX developed by Creative is another method for surround sound especially for computer games .
The advancement of MP3 , MP3 Surround supports surround sound in compressed format. The format is designed so that even a multi-channel piece of music can be played on a conventional MP3 player. The "MP3 SX" (MP3 Stereo eXtended) software is a converter that converts existing MP3 files into surround sound.
- Rolf Seidelmann: Surround in the music studio . Wizoobooks, Bremen 2008, ISBN 978-3-934903-69-2 .