How to use audio monitoring in smart security

On April 5, the "Yitie Hotel Incident" shocked the whole country. The video surveillance in the hotel recorded the whole process of a woman being violently assaulted. However, even in front of the real surveillance footage, many netizens still shouted "I don't believe it" and hoped for a reversal of the incident.

Now, let's imagine it. If the camera of Yihe Hotel is integrated with the audio system, and if the security system of Yihe Hotel has an audio system, then, under the dual evidence of picture + sound, will there be fewer voices of doubt, and will we be closer to the truth?

Audio monitoring has great potential in smart security.

Audio monitoring is an important part of the smart security construction system. It is a comprehensive system with strong prevention capabilities. Its outstanding features are intuitive, accurate, timely and rich information content.

For audio and video integrated monitoring, the camera is equivalent to the eyes and the microphone is equivalent to the ears. The images seen by the eyes and the sounds heard by the ears are transmitted to the storage server through the nervous system such as optical fiber and network to form a complete audio and video monitoring system, providing high-quality and complete basic data for smart security or smart cities.

Traditional video surveillance systems have no sound, just like early silent movies, people can only see silent images. Now, many smart security systems have required the addition of audio collection. For example, in the fields of safe cities, public security and judicial case handling areas, financial institutions, public transportation, education invigilation, administrative services, law enforcement evidence collection, etc., more and more high-quality projects require high-definition and high-fidelity audio and video synchronous monitoring systems. The importance of audio monitoring has been highlighted in high-quality security projects, becoming a new highlight of safe cities and smart government affairs.

Audio monitoring system and its role

A complete audio monitoring system includes microphones and voice noise reduction equipment, network recording intercom system, and audio intelligent analysis system.

Microphone: The microphone is the core of the audio monitoring system, which mainly collects the sound on the scene through the vibration of the sound. The microphone is generally divided into digital microphones and analog microphones. The digital microphone is a sound sensing device that converts the analog audio signal into a digital signal through a digital signal processing system and performs corresponding digital signal processing. The analog microphone simply uses a general analog circuit to amplify the sound collected by the microphone.

 

Network recording intercom system: mainly includes remote recording system and intercom system. Once the sound is collected, the recording function will be automatically started, and the real-time monitoring function will be realized mainly through voice cards and speakers.

Audio intelligent analysis system: Audio intelligent analysis is similar to the intelligent analysis in the video surveillance system. Through voiceprint collection and comparison, the specific characteristics of the sound can be analyzed, and the application scenario at that time can be analyzed.

What can the intelligent audio system do?

After years of development, audio monitoring technology is becoming mature.

The identity of an individual can be identified by identifying the voiceprint. The production of human language is a complex physiological and physical process between the human body's language center and the pronunciation organ. The vocal organs (tongue, teeth, larynx, lungs, nasal cavity) used by people when speaking vary greatly in size and shape, so everyone's voiceprint map is unique, with both relative stability and some variation. However, since everyone's pronunciation organs are different, in general, the audio system can be used to distinguish the voices of different people or determine whether it is the voice of the same person. The

abnormal behavior in the scene at that time can be judged through the scene analysis of audio monitoring. This technology is based on the characteristics of various abnormal sounds in the time domain and frequency domain, combined with the classification method of pattern recognition to alarm abnormal events.

In fact, some manufacturers' technologies can already judge the speaker's emotions, the environment in which he is in, and other issues through sound recognition.

Difficulties in the promotion of audio monitoring

As mentioned earlier, traditional monitoring systems rarely have integrated audio systems. Only in special projects, according to project requirements, will the audio system be added to the original monitoring system. The following aspects restrict the application of audio monitoring in the security industry.

1. Cost issues. Whether it is to build a complete audio system or to integrate audio products in the original monitoring system or alarm system, it will increase costs, which has become an important reason for the difficulty in promoting audio monitoring. At the same time, in some industries other than public security and banking, the audio system is not indispensable, so considering the cost issue, the audio system can be eliminated.

2. Technical difficulties. It is not difficult to integrate the audio system in the original security system, and the general technical difficulties can be basically solved. But some special industries have extremely high requirements for audio. In an open and noisy environment, the audio system is required to have strong anti-interference ability and powerful noise removal technology. Special quiet environments require very subtle sounds to be heard, such as interrogations and gun rooms inspected by the public security. Slight sounds can be collected at the first time, requiring the sensitivity of the microphone to be very high and to achieve the effect of the original sound. In short, the requirements for audio monitoring equipment in different fields are also very different. This is also the important reason why the technical standards for audio monitoring have never been uniformly standardized.

3. Privacy issues. Audio monitoring provides convenience and security, but it may also bring privacy issues. Some people worry that voiceprints can be used to identify speakers without their consent, and whether they violate their privacy and freedom of speech. Once these technologies mature, they will inevitably cause many privacy issues, which is very easy to understand. How to obtain voiceprints and when it is legal to obtain voiceprints is a very vague question. With the advancement

of safe cities and the acceleration of the anti-terrorism process, the requirements for the construction of security systems are getting higher and higher. People have begun to pay attention to audio monitoring, and the demand for audio and video synchronization monitoring in more industries and scenarios is becoming more and more intense. Whether it is public security, procuratorial and judicial agencies, or key units such as airports, railways, and banks, more and more high-quality security projects are in urgent need of clear and realistic audio and video synchronization monitoring systems.