Leveraging Speech Recognition Systems to Prevent Terrorism Against Soft Targets

A blog post from Vicomtech

In today's world, soft targets, such as places of worship, schools, and public events, are increasingly vulnerable to terrorist attacks. These attacks can have devastating consequences, both in terms of loss of life and psychological trauma. Fortunately, there are a number of technologies that can be used to help prevent these attacks, and speech recognition systems are among the most promising. 

Automatic Speech Recognition (ASR) systems can be used for instance to transcribe negotiations between police and a terrorist who has hostages. This can be a valuable tool for law enforcement, as it can help them to better understand the situation and make informed decisions. For example, by listening and carefully analyzing the terrorist's demands, law enforcement can identify potential threats and prepare accordingly. 

In addition to providing insights, these tools can also be used to analyze past negotiations, which can help law enforcement to identify patterns and develop strategies to deal with future incidents. Additionally, the generated negotiation transcripts can be used for training of negotiation officers and for evidence purposes. 

Current solutions rely heavily on a police officer that has to carefully listen and transcribe the negotiation recordings, which reduces valuable time that can be used by the officer for other research and evidence collecting tasks. There is also a limitation in the number of recordings that can be processed in certain periods of time, to be stored as evidence or to be used as training material for future situations. 

The use of speech recognition systems in hostage negotiation is still in its early stages, but the technology has the potential to make a significant contribution to preventing terrorism against soft targets. As the technology continues to develop, it will become even more effective and widely used. 

Developments within APPRAISE  

Within the project, a specifically designed ASR system was developed and tested in a realistic simulated cold weapon attack scenario. In this case, we collected and analyzed a telephone hostage negotiation between a police officer and a terrorist that threatened several hostages with a knife while kept them locked inside a room. 

The system had to deal with different challenges like the low quality audio in the telephone conversation, the use of spontaneous and emotional speech during the negotiations, and to the fact that the negotiation was performed in a low resource and challenging language like Polish. 


The impression and feedback given by local authorities validated the performance of the tool for such a difficult domain. The most important aspects of the hostage negotiations are kept in the automatic transcriptions and they can be used by law enforcement agents to identify patterns and develop strategies for dealing with future incidents. 

Benefit for the protection of public spaces   

Specific benefits of using speech recognition systems for the protection of public spaces include: 

  • Real-time insights: ASR systems can provide law enforcement with real-time insights into the negotiation, allowing them to make informed decisions more quickly. 
  • Keyword Spotting: The system can be able to detect specific keywords during the conversation in real time, and trigger certain events or flags that can be used by LEAs to make better informed decisions during the negotiation process. 
  • Pattern recognition: By analyzing past negotiations, ASR systems can help law enforcement to identify patterns and develop strategies for dealing with future incidents. 
  • Training and research: These systems can be used to create transcripts of negotiations that can be used for training and research purposes. 

Additional Considerations 

In addition to the benefits mentioned above, there are also some additional considerations to keep in mind when using ASR systems in a forensic domain. 

  • Accuracy: The systems are not perfect, and there is always a chance that the transcription will be inaccurate. Law enforcement should carefully review the transcriptions to ensure that they are accurate before making any decisions. 
  • Context: It is important to remember that ASR systems do not understand the context of the conversation. Law enforcement should use their own judgment to interpret the transcriptions. 
  • Ethics: There are some ethical concerns associated with using speech recognition systems in hostage negotiation. For example, there is a risk that the technology could be used to invade the privacy of the people involved. Law enforcement should carefully consider the ethical implications of using the technology before deploying it. 

Despite these considerations, the benefits of using speech recognition systems in hostage negotiation far outweigh the risks. This technology has the potential to save lives and protect communities from terrorism.