Whistling Noise after shut off
I'd say the water pressure is too high. As the valve closes, the water rushes through a smaller and smaller hole.  The pitch of the sound of the water moving through the valve increases, as the size of the hole decreases.  

Whistling works similarly.  You make a small hole with your lips and tongue, and force air through the hole.  The harder you blow, the louder the sound. The smaller the hole, the higher the pitch.

Measure the water pressure, and adjust/install a pressure reducing valve.