Noise reduction techniques have been applied to analogue tape machines of all formats, radio microphones, radio transmission and reception, land lines, satellite relays, gramophone records, and even some digital tape machines. The general principles of operation will be outlined, followed by a discussion of particular well-known examples. Detailed descriptions of some individual systems are referred to in the Further reading list at the end of this chapter.
Why is noise reduction required?
A noise reduction system, used correctly, reduces the level of unwanted signals introduced in a recording–replay or transmission–reception process (see Figure 7.1). Noise such as hiss, hum, and interference may be introduced, as well ...