What if there is a sound like a whistle when driving in the morning?

First of all, according to the situation you described and the nature and characteristics of the sound, if the new car that has been started for more than a month only appears the above phenomenon in the morning and disappears after the car is hot, then the above whistle sound is probably due to the intake noise caused by the change of throttle or idle valve opening, and it is not a fault for the above phenomenon.