7. A system comprising: at least one processor; and one or more non-transitory computer-readable media storing executable instructions that, when executed by the at least one processor, cause the system to: characterize a speech input based on a dynamic noise adaptation (DNA) model reflecting effects of background noise; characterize the speech input based on a null noise DNA model reflecting a null noise mismatch condition; perform Bayesian model averaging using a first weighting of the DNA model and a second weighting of the null noise DNA model; re-weight the DNA model and the null noise DNA model by adjusting the first weighting to increase a probability of the DNA model predicted by the Bayesian model averaging when the DNA model is more likely than the null noise DNA model to best characterize the speech input; and perform recognition of the speech input using the re-weighted DNA model and the re-weighted null noise DNA model.
7. A system comprising: at least one processor; and one or more non-transitory computer-readable media storing executable instructions that, when executed by the at least one processor, cause the system to: characterize a speech input based on a dynamic noise adaptation (DNA) model reflecting effects of background noise; characterize the speech input based on a null noise DNA model reflecting a null noise mismatch condition; perform Bayesian model averaging using a first weighting of the DNA model and a second weighting of the null noise DNA model; re-weight the DNA model and the null noise DNA model by adjusting the first weighting to increase a probability of the DNA model predicted by the Bayesian model averaging when the DNA model is more likely than the null noise DNA model to best characterize the speech input; and perform recognition of the speech input using the re-weighted DNA model and the re-weighted null noise DNA model. 11. The system of claim 7 , wherein the DNA model comprises a probability-based noise model reflecting transient components and evolving components of a current noise estimate of the background noise.