But there will still be a lag in the time it takes for officers to respond with an active, on-site presence unless the video is coupled with sound. As a surveillance system monitors an event, dispatchers can send officers, fire fighters or EMTs to the site and provide warnings and instructions to those involved in the incident. In addition, cameras are generally equipped with microphones, which can relay sound from the scene back to dispatchers, providing true two-way communication in real time.
Incidents can occur on city streets, college and school campuses, hospitals, office and industrial parks, theme parks and zoos and other public venues. They can include:
- Robberies and physical assaults
- Slips and falls
- Automobile accidents
- Pedestrians struck by vehicles
- Warnings to seek shelter
The real-time response can be as specific as video seen by monitors and dispatchers. The key is assigning an identifiable address for each speaker and the cameras to which it is linked. In technology, this is known as an IP address. Just as each camera is assigned an IP address that can identify its physical location through a database in a central base station that serves a command center, each speaker can have a similar IP address.
This capability opens a number of possibilities for developing and implementing policies and procedures for responding to incidents in any type of jurisdiction.
A crime in a neighborhood or business district is an example that comes immediately to mind. A network of outdoor loudspeakers can be tied to a specific group of cameras. If the networks allow dispatchers to follow the people involved in an incident, they can use the visual images to update responders as they approach the site. They can provide specific instructions to victims and suspected perpetrators or reassurance to victims as needed.
A similar network of cameras and speakers can help security and public safety personnel better respond to an incident on a college campus – or any campus-like setting, such as an office or industrial park or a medical center with a hospital and office buildings.
It can also help in a public venue, such as a theme park or zoo or a passenger or freight terminal. These are places where large crowds can gather and where anything from an accident or weather emergency can require specific information to people in specific locations.
The perimeter of a school or shopping mall is yet another set of locations that combine indoor and outdoor video and sound capabilities to help communicate more effectively and control a situation that can involve response activities as concerned people rush to the scene.
As the designer and manufacturer of outdoor loudspeaker systems for high-clarity voice communications in all types of emergencies and for tactical operations, IMLCORP has developed SoundCommander® SC360 wide-area fixed-location systems and deployable systems, including the SC1100 series and SC5600 acoustic hailing device (AHD) that can all integrate with other emergency response and mass notification technologies.
The SC360 loudspeaker system is a complete solution that projects crystal-clear warning tones, live and pre-recorded voice audio. With systems available in six-speaker or three-speaker arrays, it can cover over a full 360˚ area or a 1800 area. With the SC360 system, your live voice messages will be heard to extended ranges up to 800 meters in any direction in which the speakers are pointed.
For more focused sound, an SC1100 loudspeaker can project along a single street for many blocks, and SC5600 units can be mounted to project sound for long distances in areas that are somewhere in between the narrow SC1100 focus and the SC360. Both the SC1100 and SC5600 systems, like the SC360, can project crystal-clear warning tones and live and pre-recorded messages.
The selection of the actual speaker systems will depend on the area you want to cover. Because the actual speaker in all SoundCommanders are the same, systems can be easily mixed and matched to form a network that can be controlled from the same central base station, which can then be integrated with the video system and a variety of other mass notification technologies, such as alarms, signs, indoor speakers and a host of Internet-based contact systems.
The integration is essentially achieved by software, and applications can be customized to meet the specific requirements of the notification system. Each base station for SoundCommander systems can cover up to 25 broadcast nodes or locations. When using the SC360, each node can support up to four arrays, which each consist of six speakers in a single housing. Each node can be individually controlled, allowing a dispatcher or commander to access any combination of speakers to control a situation. More than one base station can control the speakers in a network.
Selecting the best speakers for a specific location in any network requires a sound survey to determine the sound levels you’ll need at each targeted point.
Use an integrated sound-level meter to measure average background sound levels – typically expressed as decibels, or dB – where you want the sound to be heard. You’ll need to overcome the loudest-possible ambient noise, such as from traffic, crowd or wind noise or mechanical equipment, depending on the type of venue you have. Log the Leq (Equivalent Average Level) background sound levels and chart the noises heard during the survey. Each reading at each location should last at least five minutes with the sound-level meter mounted on a tripod set at 5’4” in height.
You’ll want your loudspeaker to deliver sound at all of the targeted Locations 6 to 10 dB above the ambient level. Six dB is the minimum; 10 is double the ambient noise level. Make sure every vendor who bids on the project has your sound measurements so they know your requirements at each point.
Power and intelligibility are both necessary. Humans are much more sensitive to sounds in the frequency range of 400 to 6500 Hz. For best clarity and understanding, it is necessary for the harmonics of the human voice – as delivered by the speaker system – to be above 2000 Hz. Harmonic distortion should be less than 1 percent at full RMS power. You should have a loudspeaker system that meets or exceeds the 0.70 STI standard for speech intelligibility as specified in the NFPA 72 fire code. Our SC1100 and SC5600 systems both averaged 0.83 with a top reading of 0.87 STI (Speech Transmission Index) during recently conducted speech intelligibility tests.
Simply stated, don’t “cheap out” with a system designed for sirens or a lesser-quality system. For voice, several manufacturers, such as IMLCORP, offer systems such as our SoundCommander line, designed specifically for outdoor mass notification.
Tying a loudspeaker network with speakers designed and engineered for voice quality to a video network will provide better response capability. Dispatchers and commanders will be able to communicate directly with people involved in any kind of emergency in real time.
Integrating the sound and video with communications channels used by other responders will enable those responders to act more efficiently at the scene to better serve public safety needs.
Integrating sound and video information with an entire network of mass notification systems will help public safety officials better protect lives and property by providing more detailed information to people who may be near or approaching the site – or sites – of the incident.