Vocoder drift compensation by x-vector alignment in speaker
  anonymisation
Michele Panariello Massimiliano Todisco Nicholas Evans
For the most popular x-vector-based approaches to speaker anonymisation, the
bulk of the anonymisation can stem from vocoding rather than from the core
anonymisation function which is used to substitute an original speaker x-vector
with that of a fictitious pseudo-speaker. This phenomenon can impede the design
of better anonymisation systems since there is a lack of fine-grained control
over the x-vector space. The work reported in this paper explores the origin of
so-called vocoder drift and shows that it is due to the mismatch between the
substituted x-vector and the original representations of the linguistic
content, intonation and prosody. Also reported is an original approach to
vocoder drift compensation. While anonymisation performance degrades as
expected, compensation reduces vocoder drift substantially, offers improved
control over the x-vector space and lays a foundation for the design of better
anonymisation functions in the future.