A
noise cancellation
system (100) with
harmonic filtering for a vehicle audio
system, comprising: at least one first input sensor configured to receive a reference
signal (x r1 [n], x r2 [n]); at least one second input sensor configured to transmit at least two
narrowband input signals, wherein each of the input signals (x r1 [n], x r2 [n]) contains
overtone noises; a processor (105) programmed to: Receiving the reference
signal, wherein the reference
signal comprises at least two
narrowband reference signals (x r1 [n], x r2 [n]) includes, Receiving the
narrowband input signals, Applying a
gain reference control (346) to the reference signals to determine whether the frequencies of each of the reference signals (x r1 [n], x r2[n]) are within a predefined range of each other, Applying a bandpass filter (156) to one of the reference signals (x r1 [n], x r2 [n]), Applying a secondary path (376) based on the filtered reference signals (x r1 [n], x r2 [n]) to generate anti-
noise signals, and Summing (378) the anti-
noise signals and the input signals to produce an
error signal (e m [n]) at the output sensor (145), Applying an
adaptive filter (392) to the
error signal (e m [n]) to remove
overtone noise from the
error signal (e m [n]) and Removing one of the reference signals (x r1 [n], x r2 [n]) in response to the frequencies of each of the reference signals (x r1 [n], x r2[n]) are within the predefined range of each other to prevent common
overtone content from being detected on both reference signals (x r1 [n], x r2 [n]) during the
adaptation of the
algorithm.