18. An apparatus according to claim 17 , further including means for populating the database with said first feature data.
17. An apparatus for producing an audio signal as a replacement for a pre-recorded audio signal synchronized with a pre-recorded video signal, the apparatus comprising: one or more non-transitory computer readable mediums; a database populated with data representing the pre-recorded audio signal synchronized with the pre-recorded video signal, and data indicative of the timing of the pre-recorded audio signal relative to the pre-recorded video signal; means for deriving from the pre-recorded audio signal first feature data encoding audible time-varying acoustic features of a predetermined type and the timing thereof in the pre-recorded audio signal; means for receiving and storing an input audio signal having timing similar to that of the pre-recorded audio signal; means for deriving from the input audio signal second feature data encoding audible time-varying acoustic features of said predetermined type and the timing thereof within the input audio signal; means for determining timing differences existing between the first feature data and the second feature data; means for altering the timing of the acoustic features of the stored input audio signal to match the timing of the corresponding acoustic features of the pre-recorded audio signal and producing thereby an edited replacement audio signal; and means for selecting a start time for starting outputting of the edited replacement audio signal to coincide with a corresponding start time of the pre-recorded audio signal relative to the pre-recorded video signal and for starting muting of the pre-recorded audio signal.