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降噪系统可分为互补型和非互补型两类。录音机中使用的降噪系统多属互补型系统。如dolby、dbx、High—com、NARS、Telecom、ADRES 等系统均属此类。所谓互补就是在录音之前对信号的动态范围进行压缩,在放音之后对动态进行扩张以还原成原来的声音。而噪声不经过压缩只经过扩张,所以随着信号低电平的扩张,噪声也同时被降低了。广泛使用的dolby 系统,其压缩曲线在对数坐标上是非线
Noise reduction system can be divided into two types of complementary and non-complementary. Noise reduction systems used in the recorder are mostly complementary systems. Such as dolby, dbx, High-com, NARS, Telecom, ADRES and other systems belong to this category. The so-called complementary is the dynamic range of the signal before compression to compress the dynamic expansion after playback to restore the original sound. The noise is not compressed only through the expansion, so as the signal low-level expansion, noise is also reduced at the same time. The widely used dolby system whose compression curve is non-linear on a logarithmic scale