Emperor Penguins Aptendodytes forsteri are able to add a sequence of syllables into their song. The proportion of songs having an additional sequence varies through the breeding season. The proportion of songs having an additional sequence increases because the percentage of one-sequence songs decreases and the percentage of three-sequence songs increases. Short songs were more inclined to be lengthened by an additional sequence: at the minimal percentage of one-sequence songs is more quickly attained than the maximal percentage of three-sequence songs; b) the proportion of lengthened one-sequence songs is three times higher than the proportion of lengthened two-sequence songs; e) twenty-one birds singing short and long variants have been recorded: 20 of them sang short variants whose duration was shorter than the mean measured for the population. The sound pressure level varies through the breeding season. Conclusion: Redundancy by an additional sequence found in songs of emperor penguins may be the result of the increase of the ambient noise level of the colony.