Audio intelligence with Praesensa

Issue 4 2021 CCTV, Surveillance & Remote Monitoring

Praesensa was launched at the end of 2019 to offer quality, security and reliability in public address and voice alarm (PA/VA) systems. The latest addition to the family is the Praesensa Ambient noise sensor, particularly relevant for applications such as campuses, shopping malls, airports, railway terminals, factories and more.

The loud buzz of a crowd, the passing roar of vehicles or the hum of equipment can affect the intelligibility of voice messages. Similarly, music or messages can cause discomfort when they are played too loudly in a quieter building. Automatic Volume Control (AVC) technology helps to deal with these ambient noise changes. AVC – also known as Noise Dependent Volume Control (NDVC) – changes the loudspeaker volume according to the ambient noise levels and automatically solves the dilemma of a system being too loud in a quiet environment versus too soft in a noisy environment.

The new Praesensa Ambient noise sensor monitors the ambient noise level and alerts the system controller about changes. Announcements are then automatically adjusted to a comfortable level above the ambient noise to ensure intelligibility and background music is adjusted to maintain the right atmosphere.

Up to four sensors can operate together to cover a large area. In the event of a failure or disconnection of the device, the announcement volume is automatically set to its maximum within the applicable control range. This fail-safe ensures that the system will never interpret a missing sensor as a silent ambient level and decrease the announcement level mistakenly. The intelligibility of messages is ensured and the system remains safe.

For AVC actions to be discreet yet effective, its adaptation threshold, range, slope and speed can be optimally configured for a specific application and location. Furthermore, its behaviour is different for short announcements compared to ongoing background music. Sample-and-hold mode is used for live speech calls and playback of pre-recorded messages. The noise level is sampled and the latest level information is held and used during the call; this is not affected by the sound of the call itself or its associated reverberation and echoes. Tracking mode is used for background music; the ambient noise level is tracked, allowing the continuous adjustment of the background music’s volume to suit the environment.

The sensor is directly connected to the IP network – just one CAT5e cable can accommodate data exchange and power over Ethernet (PoE). The device communicates ambient noise level data directly to the Praesensa system controller, which adjusts the output level of the involved amplifier channels accordingly. Because only level information is exchanged and no audio data, the occupied network bandwidth for this function is minimised and there is no risk of audio eavesdropping.

A back box is included for mounting on solid ceilings and walls. Without the back box, the sensor can be flush mounted in hollow walls or suspended ceilings. The device is water resistant (IP54) with or without the back box and can be used indoors and outdoors. It comes with a black and white front cover for inconspicuous installation.


Share this article:
Share via emailShare via LinkedInPrint this page

Further reading:

Passion, drive and hard work
Technews Publishing Editor's Choice CCTV, Surveillance & Remote Monitoring Security Services & Risk Management
Colleen Glaeser is a leader in the security market, having made her mark in the male-dominated security industry through determination and hard work, along with a vision of making the world a safer place.

New full-colour Smart Dual Illuminators camera series
Dahua Technology South Africa Products CCTV, Surveillance & Remote Monitoring
Using deep learning to accurately detect targets, the cameras can intelligently switch between the IR mode when there is no target, and full-colour mode when a target is detected.

2022 trends in video surveillance
Eagle Eye Networks Editor's Choice CCTV, Surveillance & Remote Monitoring Integrated Solutions
Eagle Eye Networks predicts what will impact the video surveillance industry in the coming year and how to seize opportunities and forge a path to success, even amid ongoing uncertainties.

Dahua launches thermal monocular camera series
Dahua Technology South Africa CCTV, Surveillance & Remote Monitoring
Dahua has launched its Thermal Monocular Camera Series, the M Series, for outdoor scenarios, sporting a 12 µm Vox sensor that offers a maximum resolution of 640 x 512.

Solar-powered cameras keep construction site safe
Hikvision South Africa CCTV, Surveillance & Remote Monitoring
In the midst of a rise in building material thefts, construction company DECHO used Hikvision’s solar-powered wireless cameras to guard the construction site for its much-anticipated Coast Garden project.

The impact of AI-enhanced video analytics on control room personnel
Leaderware Editor's Choice CCTV, Surveillance & Remote Monitoring
What impact do AI-capable detection systems have on control room staff, and do they mean a change in the demands on operators and the type of people you have in the control room?

Integrated technology ecosystem for safe hospitals
Avigilon CCTV, Surveillance & Remote Monitoring
SSM Health chooses Motorola Solutions Safe Hospitals’ integrated technology ecosystem, an end-to-end security ecosystem that unifies voice, video, data and analytics on one single platform.

Smartphone capabilities and CCTV
Forbatt SA CCTV, Surveillance & Remote Monitoring
TVT’s mobile app puts useful information in the hands of users in an easy to understand and operate format, ensuring users stay abreast of what is happening in their environment.

To be or not to be, is that the objective?
Iris AI Editor's Choice CCTV, Surveillance & Remote Monitoring News
Gerhard Furter joins a discussion on the nature of sentience in artificial intelligence. Do we actually know what sentience is, or are we overestimating our human capabilities?

Securing the diamond industry
Milestone Systems CCTV, Surveillance & Remote Monitoring
Milestone’s open platform XProtect manages 20 acres and over 3500 cameras while integrating additional applications for more effective security, even via mobile devices.