Reduced-bandwidth speech enhancement with bandwidth extension

An ear-wearable electronic device, comprising:

• at least one microphone configured to convert sound that includes speech to an electrical signal;
• a loudspeaker;
• an analog to digital converter that converts the electrical signal to a digitized signal;
• and
• a processor operably coupled to the microphone, the loudspeaker, and the analog to digital converter, the processor operable to:
• apply a low-pass filter at a cut-off frequency to the digitized signal to remove a high-frequency component and obtain a low-frequency component;
• applying speech enhancement to the low-frequency component;
• applying blind bandwidth extension to the enhanced low-frequency component to recover or synthesize an estimate of at least part of the high frequency component;
• and
• output an enhanced speech signal via the loudspeaker that is a combination of the enhanced low-frequency component and the bandwidth-extended high frequency component;
• and
• update the cutoff frequency of the low-pass filter during use of the ear-wearable device based on iteratively updating an average of the signal quality estimates for frequency bands below the cutoff frequency with signal quality estimates of additional sub-bands greater than the cutoff frequency until the updated average is less than a threshold, the updated value of the cutoff frequency being based on a highest frequency sub-band of the additional sub-bands.

An ear-wearable electronic device, comprising:

• at least one microphone configured to convert sound that includes speech to an electrical signal;
• a low-pass filter that obtains a low-frequency component from the electrical signal;
• a speech enhancement processor that uses machine-learning to produce a narrowband enhanced excitation signal from the low-frequency component;
• an excitation extension module that frequency-extends the enhanced narrowband excitation signal to a wideband enhanced excitation signal;
• a linear predictive coder (LPC) that produces a spectral envelope extension from the low-frequency component;
• and
• a loudspeaker that converts an enhanced speech signal into audio, the enhanced speech signal comprising a convolution of the wideband enhanced excitation signal and the spectral envelope extension, wherein a cutoff frequency of the low-pass filter is updated during use of the ear-wearable device based on iteratively updating an average of the signal quality estimates for frequency bands below the cutoff frequency with signal quality estimates of additional sub-bands greater than the cutoff frequency until the updated average is less than the threshold, the updated cutoff frequency being based on a highest frequency sub-band of the additional sub-bands, wherein the signal quality estimates comprise at least one of a posteriori signal-to-noise-ratio (SNR) and a coherent-to-diffuse power ratio (CDR).