Computerized estimation of an identity of a user of a computing system. The system estimates environment-specific alterations of a received user sound that is received at the computing system. The system estimates whether the received user sounds is from a particular user by use of a corresponding user-dependent audio model. The user-dependent audio model may be stored in a multi-system store accessible such that the method may be performed for a given user across multiple systems and on a system that the user has never before trained to recognize the user. This reduces or even eliminates the need for a user to train a system to recognize the voice of a user, and allows multiple systems to take advantage of previous training performed by the user.