1. A method, comprising: detecting receipt of an audio signal that is sampled into blocks; determining a plurality of energy values of the sampled audio signal blocks; performing energy binning of the plurality of energy values to determine whether speech is present in the sampled audio signal blocks; determining that speech is present in the sampled audio signal blocks received; storing a representation of the sampled audio signal block in a trigger buffer; matching the representation of the sampled audio signal blocks stored in trigger buffer to a training sequence stored in a training buffer in reverse order; and enabling a wake up pin in a voice trigger device upon matching the representation to the training sequence.