1. A method of reducing noise in an audio signal received at a microphone for a speech-processing device, the audio signal, that is received at the microphone being represented by a plurality of consecutive frames of data, each consecutive frame of data representing a plurality of consecutive samples of the received audio signal, the method comprising: converting the audio signal received at the microphone to a plurality of consecutive frames of data representing said audio signal; determining a signal to noise ratio (SNR) for a first frame responsive to energy generated by the microphone, and responsive to the determination of a softSNR and the determination of a realSNR for the first frame; determining a warped speech probability presence (SPP) factor for the first frame using a minimum mean square error (MMSE) determiner, which uses a SPP factor determined for the first frame, multiplied by a sigmoid function having a shape, the warped SPP factor for the first frame being determined by the determiner using the signal to noise ratio determined for the first frame; determining if the warped SPP factor is between pre-determined maximum and minimum values for the warped SPP factor; adjusting the warped SPP factor responsive to the determination of whether the warped SPP factor is between the first and second pre-determined maximum and minimum values for the warped SPP factor; changing the shape of the sigmoid function responsive to determining a SPP for a second frame to provide a second frame that having a reduced noise content, the second frame following the first frame; adjusting gain applied to the second frame by an amount corresponding to the changed shape of the sigmoid function, to reduce noise content in the second frame; re-converting the reduced-noise content second frame to an audio signal; and providing the reduced noise content second frame to the speech-processing device.