A device comprising: a memory configured to store, in a database, substitute speech data corresponding to substitute speech signals and a parameterized database; and a processor configured to: generate search result data via a search of the parameterized database in the memory based on input speech data corresponding to an input speech signal using search criteria including speech parameters of the input speech data, and based on how closely related corresponding speech parameters of the parameterized database are to the speech parameters of the input speech signal; select particular search result data based on a constraint, wherein the particular search result data is associated with particular substitute speech data, and the constraint is based on a cost of retrieving a substitute speech signal associated with the corresponding search result, one or more prior substitute speech signals, one or more subsequent substitute speech signals, or a combination thereof; generate processed speech data by replacing a portion of the input speech data with replacement speech data, wherein the replacement speech data is determined based on the particular search result data; and generating an output signal by encoding the processed speech data. a memory configured to store, in a database, substitute speech data corresponding to substitute speech signals and a parameterized database; and a processor configured to: generate search result data via a search of the parameterized database in the memory based on input speech data corresponding to an input speech signal using search criteria including speech parameters of the input speech data, and based on how closely related corresponding speech parameters of the parameterized database are to the speech parameters of the input speech signal; select particular search result data based on a constraint, wherein the particular search result data is associated with particular substitute speech data, and the constraint is based on a cost of retrieving a substitute speech signal associated with the corresponding search result, one or more prior substitute speech signals, one or more subsequent substitute speech signals, or a combination thereof; generate processed speech data by replacing a portion of the input speech data with replacement speech data, wherein the replacement speech data is determined based on the particular search result data; and generating an output signal by encoding the processed speech data. generate search result data via a search of the parameterized database in the memory based on input speech data corresponding to an input speech signal using search criteria including speech parameters of the input speech data, and based on how closely related corresponding speech parameters of the parameterized database are to the speech parameters of the input speech signal; select particular search result data based on a constraint, wherein the particular search result data is associated with particular substitute speech data, and the constraint is based on a cost of retrieving a substitute speech signal associated with the corresponding search result, one or more prior substitute speech signals, one or more subsequent substitute speech signals, or a combination thereof; generate processed speech data by replacing a portion of the input speech data with replacement speech data, wherein the replacement speech data is determined based on the particular search result data; and generating an output signal by encoding the processed speech data.