Why am I hearing a humming sound from my LED array?

Hi,

I have been working on this consumer electronics project which uses LT3599 LED driver to control a 4 channel LED ring.

Here, I have used True colour PWM led brightness control & the problem is that, while the LED ring is on, I could hear small humming sound from the LED ring itself.

What could be causing this humming sound?

Is there any remedy to prevent or to reduce this effect?

Except for some changes in the current control resistors, the LED driver circuit is just like the one in the datasheet.

Thanks & Regards,

Hari