  Voice triggering (VT) enables users to activate their devices by just
speaking a trigger phrase. A front-end system is typically used to perform
speech enhancement and/or separation, and produces multiple enhanced and/or
separated signals. Since conventional VT systems take only single-channel audio
as input, channel selection is performed. A drawback of this approach is that
unselected channels are discarded, even if the discarded channels could contain
useful information for VT. In this work, we propose multichannel acoustic
models for VT, where the multichannel output from the frond-end is fed directly
into a VT model. We adopt a transform-average-concatenate (TAC) block and
modify the TAC block by incorporating the channel from the conventional channel
selection so that the model can attend to a target speaker when multiple
speakers are present. The proposed approach achieves up to 30% reduction in the
false rejection rate compared to the baseline channel selection approach.
