一种独特的声频扩频方法可以识别声频路径,这种方法用于消费类电子产品。图1(a)所示电路采用了一种注入式的声频扩频标记信号,因为听音者并不能发觉在声频通带中的低电平噪声,而可听见一个恒定标记信号。本电路将把标记信号注入各种可能路径的不同的输入端,然后在其输出端,或在扬声器处检测标记信号。 A unique audio spread spectrum method to identify the audio path, this method is used in consumer electronics. The circuit shown in Figure 1 (a) uses an injection-type audio spread-spectrum tagging signal because a listener can not perceive low-level noise in the audio passband and can hear a constant mark signal. The circuit will inject the mark signal into various inputs of various possible paths and then detect the mark signal at its output or at the loudspeaker.