Cause of engine noise difference with abrupt acceleration from stop.

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When I accelerate from a stop (e.g. at a Green light) there is hesitation and the engine sounds like it is going into "turbo charge" and then returns to normal engine noise. This noise does NOT occur when accelerating rapidly when car is moving. "Mechanic" replaced LAF sensor however it is not resolved. Request EXPERT, QUALIFIED response PLEASE. TY.