Systems and methods for suppressing noise in an audio signal for subbands in a frequency domain based on a closed-form solution

A system for reducing noise from an input signal to generate a noise-reduced output signal, the system comprising:

• a time-to-frequency transformation device configured to transform an input signal from a time domain to a plurality of subbands in the frequency domain, wherein each subband of the plurality of subbands includes a speech component and a noise component;
• a filter coupled to the time-to-frequency device, the filter being configured to:
• for each of the subbands, estimate an amplitude of the speech component based on a minimization of a normalized mean square error, wherein the normalized mean squared error is based on a mean squared error represented by E[(A−Â)|Y], where  is an estimate of the amplitude of the speech component, A represents an actual value of the amplitude of the speech component, Y is the amplitude of the subband, and E is an expected value operator, and
• filter the plurality of subbands in the frequency domain based on the estimated amplitudes of the speech components to generate the noise-reduced output signal;
• and
• a frequency-to-time transformation device configured to transform the noise-reduced output signal from the frequency domain to the time domain.