When accelerating there is a high pitched squeal/whistle sound

I've been getting a high pitched squeal/whistle sound when accelerating, it's not every time but only happens under acceleration and it doesn't matter if it's from a stand still or going from a low speed to a higher speed and stops as soon as I let off the gas pedal. It's definitely not any sort of belt squeal and I'm not having any idle issues. Could it possibly be a transmission issue?