Method and apparatus for estimating subjective audio signal quality from objective distortion measures

An apparatus comprising a processing system operative to generate a mapping function between a plurality of actual subjective measures determined for a given set of audio signals and corresponding objective distortion measures determined for the given set of audio signals, and to utilize the mapping function to generate an estimated subjective measure from an objective distortion measure determined for another audio signal;

• wherein a portion of at least one of the objective distortion measures associated with an mth frame of a given source speech sequence is given by D ⁢ ( m ) = ∑ i = 1 N b ⁢ ⁢ C ⁢ ( m , i ) ⁢ [LeftBracketingBar] X ⁢ ( m , i ) - Y ⁢ ( m , i ) [RightBracketingBar]
• where X(m, i) and Y(m, i) are auditory representations of source and processed speech, respectively, for the sequence, 1≦i≦Nb denotes a frequency bin index, Nb is the dimension of a frame vector, and C(m, i) is an asymmetric weighting factor;
• wherein an overall auditory-based objective distortion measure between the source and processed speech sequences X and Y is determined by
• D=γDsp+(1−γ)Dnsp
• where γ is a weighting factor for active speech frames, and Dsp and Dnsp are distortions for speech and non-speech portions of the sequences, respectively;
• and
• wherein the distortions for the speech portion Dsp and the non-speech portion Dnsp are defined as D sp = 1 max m ⁢ L Y ⁡ ( m ) · T sp ⁢ ∑ m , L X ⁡ ( m ) > K ⁢ ⁢ D ⁡ ( m ) D nsp = 1 max m ⁢ L Y ⁡ ( m ) · T nsp ⁢ ∑ m , L X ⁡ ( m ) ≤ K ⁢ ⁢ D ⁡ ( m )
• where Lx (m) and Ly (m) are pseudo-loudness of the source speech and the processed speech at the mth frame, respectively, K is a threshold for speech/non-speech decision, and Tsp and Tnsp are the number of active speech frames and the number of non-speech frames, respectively.

An article of manufacture comprising a machine-readable medium for storing one or more software programs which when executed in a data processor implement the steps of:

• generating a mapping function between a plurality of actual subjective measures determined for a given set of audio signals and corresponding objective distortion measures determined for the given set of audio signals;
• and
• utilizing the mapping function to generate an estimated subjective measure from an objective distortion measure determined for another audio signal;
• wherein a portion of at least one of the objective distortion measures associated with an mth frame of a given source speech sequence is given by D ⁢ ( m ) = ∑ i = 1 N b ⁢ ⁢ C ⁢ ( m , i ) ⁢ [LeftBracketingBar] X ⁢ ( m , i ) - Y ⁢ ( m , i ) [RightBracketingBar]
• where X(m, i) and Y(m, i) are auditory representations of source and processed speech, respectively, for the sequence, 1≦i≦Nb denotes a frequency bin index, Nb is the dimension of a frame vector, and C(m, i) is an asymmetric weighting factor;
• wherein an overall auditory-based objective distortion measure between the source and processed speech sequences X and Y is determined by
• D=γDsp+(1−γ)Dnsp
• where γ is a weighting factor for active speech frames, and Dsp and Dnsp are distortions for speech and non-speech portions of the sequences, respectively;
• and
• wherein the distortions for the speech portion Dsp and the non-speech portion Dnsp are defined as D sp = 1 max m ⁢ L Y ⁡ ( m ) · T sp ⁢ ∑ m , L X ⁡ ( m ) > K ⁢ ⁢ D ⁡ ( m ) D nsp = 1 max m ⁢ L Y ⁡ ( m ) · T nsp ⁢ ∑ m , L X ⁡ ( m ) ≤ K ⁢ ⁢ D ⁡ ( m )
• where LX (m) and Ly (m) are pseudo-loudness of the source speech and the processed speech at the mth frame, respectively, K is a threshold for speech/non-speech decision, and Tsp and Tnsp are the number of active speech frames and the number of non-speech frames, respectively.