Description
The Bosch PRA-ANS Ambient Noise Sensor monitors changing ambient noise levels for automatic adjustment of announcement or background music levels (AVC – Automatic Volume Control). This ensures the public address audio is set at a configurable level above the ambient noise in order to guarantee intelligibility of announcements, yet at a comfortable loudness.
IP-Network Connection
- Direct connection to the IP‑network. One shielded CAT5e cable is sufficient for Power over Ethernet and data exchange.
- The ambient noise sensor communicates ambient noise level data directly to the system controller. The system controller 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 minimized and there is no risk of audio eavesdropping.
Operation
- The ambient noise level is measured using an accurate omni-directional MEMS microphone. An integrated DSP allows for frequency response adjustments for optimum tracking of disturbing noise signals and/or minimizing the influence of non-disturbing out-of-band signals.
- Up to four sensors can operate together to cover a large area; the ambient noise level information of these sensors is combined.
- Fail-safe operation: upon failure or disconnection of the device, the announcement volume of the subscribing amplifier channels is automatically set to its maximum within the applicable control range.
- The device uses two modes for operation:
– The sample-and-hold mode is used for live speech calls and playback of prerecorded messages. The noise level is sampled and the last level information is hold and used during the call, not affected by the sound of the call itself and its associated reverberation and echoes.
– The tracking mode is used for background music. The noise level is tracked and the volume of the background music is continuously adapted. Because in this mode the ambient noise level is ‘polluted’ by the sound from the PA system itself, in this mode the ambient noise sensor must be mounted close to the expected noise location and away from the PA-loudspeakers to prevent volume runaway. - Front side LEDs show the operational status.