Howling Suppression Method - Active Suppression and Passive Suppression

- Jul 26, 2018-

The excessive performance of feedback in the sound reinforcement system is howling. Howling is the performance of the microphone's sound gain boost limit, which is the result of peak-to-peak superposition. Aiming at the generation of this phenomenon, people have proposed a variety of methods to improve the microphone sound gain, such as reasonable sound field arrangement, increase the sound absorption material, and change the reflection characteristics of the sound and so on, so as to avoid such phenomena as much as possible. Meet the sound pressure requirements of normal sound reinforcement.

People often use the compensation means of electro-acoustic equipment to improve the microphone sound gain. The compensation methods of electroacoustic equipment are divided into active mode and passive mode.

Frequency shifting is a typical active suppression method. Its working principle is that the audio signal changes its original frequency characteristics by frequency shifting (the incoming signal is 1KHz, and the outgoing signal is 995Hz), which destroys the conditions of peak-to-peak superposition and frequency. The response curve tends to ensure that the flat sound reinforcement system obtains a higher average sound gain microphone margin space, thereby actively suppressing howling.

The equalizer is used to control the feedback. Firstly, the high burst point of the frequency response curve is found. By controlling the point, the frequency response curve is balanced, so that the sound reinforcement system can obtain the maximum sound gain space (2-6db). The feedback suppressor works as an automatic equalizer. Therefore, the equalizer and feedback suppressor used in the live sound reinforcement environment is a passive feedback suppression method.

The booster microphone gain boosting processor has two built-in feedback suppression methods, one is the pressure point (parametric equalization) mode, and the other is the frequency shifting mode. The pitch microphone gain boost processor is often used in KTV, conference and other environments.

The booster microphone gain boost processor has the following advantages:

First, the feedback suppressor used in the sound reinforcement environment is the most comprehensive means of the booster microphone gain boosting processor. Other additional control methods are not mentioned first. It has two methods: active suppression (frequency shifting) and passive suppression (parametric equalization).

Second, after accessing the system, you can achieve singing and speaking easily without the need of debugging, and prevent the purpose of howling. In terms of the system's sound gain enhancement capability, the booster microphone gain boost processor can be boosted by 3-8db. The traditional feedback suppressor can only improve 2-6db, and it requires complicated debugging.

Third, the microphone gain boost processor has almost no hearing distortion. The conventional feedback suppressor has constant pressure point amplitude of -9db in the automatic state, which inevitably causes great hearing distortion. Due to the processing speed, many feedback suppressors produce a phenomenon of sound lag.

Fourth, the line interface with a microphone. Conventional feedback suppressors have only line interfaces, and many card package amplifiers do not have a line access point for the microphone. If the feedback suppression process is not available, this makes the conventional feedback suppressor unusable in such an environment.

 

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