By identifying undesirable sounds in the cabin and then playing back through the speakers sound waves of opposite phase, the original noises are cancelled out, making the M's interior a quieter, more restful place to be. The system is aimed at reducing undesirable low-frequency engine sounds only. Infiniti M models with the 16-speaker Bose® Studio Surround® sound system are equipped with Bose Engine Harmonic Cancellation (EHC) which is even more effective at controlling unwanted noises.