In spectral analysis and pattern recognition, especially in speech pro
cessing, AutoRegressive (AR) modeling is widely used as a signal param
eter estimation tool. In this paper, AR estimation behaviour is studie
d when applied to signals presenting abrupt changes at an unknown inst
ant of time. A particular abrupt change is studied : the additive chan
ge case. This change occurs when, at the instant of change, a signal a
dds to one which was present before - both signals are independent -.
The theoretical sliding window AR parameter expressions are given. We
show that blind sliding window AR estimation can lead to a detection t
ool, allowing additive changes to be detected and distinguished.