请音保密可以使电话和无线通信的信息增加安全性。虽然把语音分解成几个频段并对它们进行倒频可以实现高级加密但是，把语音频谱反转，使它不可理解，也可达到简单加密的目的。当３００～３４００Ｈｚ频段的语音乘上４ｋＨｚ单音时，就可得到一个围绕４ｋＨｚ有２个边带的抑制 Keeping your voice secure increases the security of your phone and wireless communications. Although breaking down speech into several frequency bands and scrambling them can achieve advanced encryption, however, the speech spectrum is inverted to make it incomprehensible and simple encryption can be achieved. When the 300 ~ 3400Hz frequency band multiplied by 4kHz tone, you can get a 2kHz around 4kHz suppression