In all but one respect, the functionality of the Ambient Noise Compensation block is the same as the standard Halogen ANC block. The only difference is that an additional input and output pair is provided. Room In, Room Out and Ambient Noise function as before. The gain adjustment calculated for the primary channel is then applied to the Reference channel.
The block is used in applications where a slave-channel (Reference In) needs to track the gain of a primary channel (Room In). An Example is when AEC reference and room signals require the same processing. The ambient sensing microphone should be placed as close as possible to the noise source, and as far away as possible from the program speaker(s) to reduce acoustic coupling. Multiple noise sensing microphones can be mixed together using a Mixer block that feeds the ambient input. The ANC block uses a modeling algorithm that allows it to significantly reduce its own program material from the ambient noise microphone (a 20 dB reduction of the program material at the noise microphone is typical). The modeling is done continuously during normal block operation and is stored in the internal DSP’s memory.
See Introduction to Conferencing for insight input applications.
Use of the Tracking ANC block is identical to the standard Halogen ANC Block including its typical location in a configuration. The only difference is that an additional reference channel nay be connected that allows a reference signal to track the gain adjustment of the primary Room channel.
See ANC Block, Configuring the Block.
|Room In node||Connection point for wiring the primary input to the ANC block. This input is used exclusively in combination with the Ambient Noise input to determine ANC gain. It is paired with the Room Out node.|
|Ambient Noise node||
The ANC’s ambient noise detector is fed from a side-chain input node, allowing separate processing. Connect your ambient noise input signal to this, which is from a microphone(s) in the room where the Program source is playing.
tip: A RAD17 boundary microphone works well as an ambient noise input source.
|Room Out node||Connection point for wiring the primary gain-adjusted input signal to another block, typically an output block.|
|Reference In node||Connection point for wiring a slave input to the ANC block. This input is not used for the ANC gain calculation. The gain calculated for the primary channel is applied.|
|Reference Out node||Connection point for wiring the gain-adjusted reference signal to another block, typically an AEC reference.|
(Hover over the thumbnail below to view the properties dialog box.)
The properties of the Tracking ANC Block are identical to those of the standard Halogen ANC Block with the addition of input and output meters for the reference channel. The block is typically used in a conference application using AEC where an AEC reference needs to track a Room output.