The present invention relates to a method for acoustically detecting at least one malfunction (DYS) of a motor, the motor generating a primary noise Po that is treated by an active noise control system emitting, at the noise reduction targets, an acoustic signal Pc produced by at least one actuator and connected by a transfer function H to a signal Y produced by said active noise control system, said malfunction (DYS) having an acoustic signature identifiable in the primary noise Po at the noise reduction targets, characterized in that it comprises the following steps: acquisition of said signal Y produced by the active control system; identification of the appearance, if any, of a malfunction by a monitoring means that uses the knowledge of Y and H and emits an alert message if warranted.