Method and device for the artificial extension of the bandwidth of speech signals

A device for artificial extension of bandwidth of speech signals comprising:

• an encoder device comprising:
• a first determination unit to determine signal components within an extension band of a wideband input speech signal;
• a second determination unit to determine spectral envelopes for the signal components;
• a third determination unit to determine temporal envelopes for the signal components, the temporal envelopes being determined independently of the spectral envelopes, without using the spectral envelopes as an input;
• and
• an encoder to encode the temporal envelopes and the spectral envelopes, and produce encoded information;
• and
• a decoder to decode the encoded information and regenerate the temporal envelopes and the spectral envelopes and produce a bandwidth-extended output speech signal, wherein the decoder comprises:
• an excitation signal generator to generate an excitation signal from an input signal transmitted to the decoder;
• a first correction unit to determine a first correction factor from decoded information of the temporal envelopes and from the excitation signal, and to form reconstructed temporal envelopes by multiplying the first correction factor with the excitation signal;
• and
• a second correction unit to filter the reconstructed temporal envelopes to produce pulse responses while filtering, and to form reconstructed spectral envelopes from the pulse responses and the reconstructed temporal envelopes.

A method for artificial extension of bandwidth of speech signals, comprising:

• providing a wideband input speech signal, the wideband input speech signal having an extension band outside of non-extended band;
• determining signal components within the extension band of the wideband input speech signal, the signal components being required for bandwidth extension into the extension band of the wideband input speech signal;
• determining temporal envelopes of the signal components;
• determining spectral envelopes of the signal components independently of the temporal envelopes;
• encoding information for the temporal envelopes and the spectral envelopes to produce encoded information for extending the bandwidth;
• and
• decoding the encoded information and reconstructing the temporal envelopes and the spectral envelopes from the encoded information to thereby produce an output speech signal with extended bandwidth, the decoding and reconstructing comprising:
• producing an excitation signal in a decoder from an input signal transmitted to the decoder;
• determining a first correction factor from decoded information of the temporal envelopes and from the excitation signal;
• in a first reconstruction, forming reconstructed temporal envelopes by multiplying the first correction factor with the excitation signal;
• filtering the reconstructed temporal envelopes to produce pulse responses while filtering;
• and
• in a second reconstruction, forming reconstructed spectral envelopes from the pulse responses and the reconstructed temporal envelopes.