Method of evaluating intelligibility of a degraded speech signal received from an audio transmission system, by conveying through said audio transmission system a reference speech signal such as to provide said degraded speech signal, wherein the reference speech signal conveys one or more words made up of combinations of consonants and vowels, wherein the method comprises: - sampling said reference speech signal into a plurality of reference signal frames, sampling said degraded speech signal into a plurality of degraded signal frames, and forming frame pairs by associating said reference signal frames and said degraded signal frames with each other; - providing for each frame pair a difference function representing a difference between said degraded signal frame and said associated reference signal frame; - compensating said difference function for one or more disturbance types such as to provide for each frame pair a disturbance density function which is adapted to a human auditory perception model; - deriving from said disturbance density functions of a plurality of frame pairs an overall quality parameter, said quality parameter being at least indicative of said intelligibility of said degraded speech signal; wherein, said method further comprises the steps of: - identifying, for at least one of said words conveyed by the reference speech signal, a reference signal part and a degraded signal part associated with a consonant of said consonants and vowels making up the at least one word, wherein said step of identifying said signal parts relating to the consonant is performed based on signal power of the reference speech signal; - determining, from the identified reference and degraded signal parts, for a disturbance coinciding with the consonant associated with the identified reference signal part and degraded signal part, a degree of disturbance experienced in the degraded speech signal coinciding with the consonant, based on a comparison of signal powers in the degraded signal part and the reference signal part; and - compensating the overall quality parameter dependent on the determined degree of disturbance of the disturbance coinciding with the consonant, for taking into account that disturbances which coincide with consonants in a speech signal are perceived as more destructive to information transfer than disturbances coinciding with vowels. - sampling said reference speech signal into a plurality of reference signal frames, sampling said degraded speech signal into a plurality of degraded signal frames, and forming frame pairs by associating said reference signal frames and said degraded signal frames with each other; - providing for each frame pair a difference function representing a difference between said degraded signal frame and said associated reference signal frame; - compensating said difference function for one or more disturbance types such as to provide for each frame pair a disturbance density function which is adapted to a human auditory perception model; - deriving from said disturbance density functions of a plurality of frame pairs an overall quality parameter, said quality parameter being at least indicative of said intelligibility of said degraded speech signal; - identifying, for at least one of said words conveyed by the reference speech signal, a reference signal part and a degraded signal part associated with a consonant of said consonants and vowels making up the at least one word, wherein said step of identifying said signal parts relating to the consonant is performed based on signal power of the reference speech signal; - determining, from the identified reference and degraded signal parts, for a disturbance coinciding with the consonant associated with the identified reference signal part and degraded signal part, a degree of disturbance experienced in the degraded speech signal coinciding with the consonant, based on a comparison of signal powers in the degraded signal part and the reference signal part; and - compensating the overall quality parameter dependent on the determined degree of disturbance of the disturbance coinciding with the consonant, for taking into account that disturbances which coincide with consonants in a speech signal are perceived as more destructive to information transfer than disturbances coinciding with vowels.