US 7,624,008 B2Granted

Method and device for determining the quality of a speech signal

AssigneeKoninklijke KPN N.V.

InventorsJohn Gerard Beerends, Andries Pieter Hekstra

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Abstract

Methods and devices for objectively predicting perceptual quality of speech signals degraded in a speech processing/transporting system which may have poor prediction results for degraded signals including extremely weak or silent portions. Improvement is achieved by applying a first scaling step in a pre-processing stage with a first scaling factor which is a function of a reciprocal value of power of the output signal increased by an adjustment value, and by a second scaling step with a second scaling factor which is substantially equal to the first scaling factor raised to an exponential value and with an adjustment value between zero and one. The second scaling step may be performed at various locations in the device. The adjustment values are adjusted using test signals with well-defined subjective quality scores.

Claims23

Dependent claims

Apparatus for determining, through an objective speech measurement technique, a quality signal for an output signal, of a speech signal processing system, with respect to a reference signal, the apparatus comprising:

means for pre-processing the output and reference signals to yield pre-processed signals;
means for processing the pre-processed signals so as to generate corresponding representation signals representing the output and reference signals according to a perception model, and
means for combining the representation signals to form a differential signal and for generating, in response to the differential signal, the quality signal;
wherein the pre-processing means comprise:
first means for scaling a power level of at least one signal of the output and reference signals by multiplying said one signal by a first scale factor prior to generating the corresponding representation signal therefrom, the first scale factor being a first function of a reciprocal value of a first power-related parameter of the one signal, the first power-related parameter being adjusted by a first adjustment parameter (Δ), to yield a first scaled signal;
and
second means for scaling the one signal, the differential signal or the first scaled signal through multiplication by a second scale factor so as to form a second scaled signal and thereafter using the second scaled signal instead of respectively the one signal, the differential signal or the first scaled signal, in subsequent processing to yield the quality signal, the second scale factor being a second function of a reciprocal value of a second power-related parameter of the one signal with the second power-related parameter being adjusted by a second adjustment parameter (α).

4 more elements

A method for use in apparatus that determines, through an objective speech measurement technique, a quality signal for an output signal, of a speech signal processing system, with respect to a reference signal, the method comprising the steps of:

pre-processing the output and reference signals to yield pre-processed signals;
generating, in response to the pre-processed signals, corresponding representation signals representing the output and reference signals according to a perception model;
and
combining the representation signals to form a differential signal and for generating, in response to the differential signal, the quality signal therefrom;
and
wherein the method further comprises the steps of:
first scaling a power level of at least one signal of the output and reference signals by multiplying said one signal by a first scale factor prior to generating the corresponding representation signal therefrom, the first scale factor being a first function of a reciprocal value of a first power-related parameter of the one signal, the first power-related parameter being adjusted by a first adjustment parameter (Δ), to yield a first scaled signal;
and
second scaling the one signal, the differential signal or the first scaled signal through multiplication by a second scale factor so as to form a second scaled signal and thereafter using the second scaled signal instead of respectively the one signal, the differential signal or the first scaled signal, in subsequent processing to yield the quality signal, the second scale factor being a second function of a reciprocal value of a second power-related parameter of the one signal with the second power-related parameter being adjusted by a second adjustment parameter (α).

6 more elements

Dependencies are inferred from the claim text.