Devices and methods for evaluating speech quality

An apparatus for determining a set of neural network parameters for determining a quality score for an audio signal sample, the apparatus comprising:

• a pre-processor configured to pre-process a feature value of a feature vector extracted from the audio signal sample to obtain a pre-processed feature value, wherein the feature vector comprises a plurality of feature values, and wherein each feature value is associated with a feature of the feature vector, wherein pre-processing the feature value is based on a cumulative distribution function (CDFm) associated with the feature represented by the feature value to obtain a pre-processed feature value;
• and
• a processor configured to:
• implement a neural network, and
• determine based on the pre-processed feature value the set of neural network parameters for determining the quality score for the audio signal sample.

An apparatus for determining a quality score for an audio signal sample, wherein the apparatus comprises:

• a pre-processor configured to pre-process a feature value of the feature vector extracted from the audio signal sample to obtain a pre-processed feature value, wherein the feature vector comprises a plurality of feature values, and wherein each feature value is associated with a feature of the feature vector, wherein processing the feature value is based on a cumulative distribution function (CDFm) associated with the feature represented by the feature value to obtain a pre-processed feature value, and
• (i) map the feature value of the feature to a function value of the CDFm associated with the feature to obtain an intermediate feature value, and to map the intermediate feature value to a function value of an inverse distribution function associated with the feature to obtain the pre-processed feature value, wherein the inverse distribution function is an inverse distribution function of the CDFm. associated with the feature, which is different to an original distribution function associated with the feature, or,
• (ii) map the feature value of the feature vector to a function value of a combined distribution function to obtain the pre-processed feature value, wherein function values of the distribution function correspond to function values obtainable by firstly mapping the feature value to the CDFm associated with the feature and secondly mapping the resulting intermediate feature value to a functional value of the inverse distribution function associated with the feature;
• and
• a processor configured to:
• implement a neural network, and
• determine the quality score for the audio signal sample based on the pre-processed feature value and a set of neural network parameters for the neural network associated with the CDFm.