1. A method for authenticating a user for a transaction, comprising: providing, by a device, a word string that comprises a random element; transmitting an audio segment, to a server computer, wherein the audio segment originated from the user and wherein the server computer authenticates the user for the transaction based at least in part on the transmitted audio segment; and receiving, from the server computer, an indication that the user is authenticated for the transaction, wherein the server computer holds the audio segment in a queue for a predetermined period of time, and delays updating of a fraud model with the audio segment being held in the queue until after the predetermined period of time has elapsed and when no fraud has been reported for the predetermined period of time.