I tried searching but it's hard to find references to 'sounds'. One man's warble is another man's burble.

Anyway, any ideas?:

 

Check the heatshield right above the j-pipe, next to the axle and make sure its not loose.

 

Remove the serpentine belt, start the car to see if noise dissipates, if so check all the pulleys, especially the idler pulley. If noise still persists, possible water pump or timing belt tensioner.

 

I just had the timing belt/tensioner and waterpump replaced at hamilton honda about a month ago..honestly i can't remember if the noise was there prior or not. Perhaps I should ask them about it.

I'll check the idler pulley..seems logical.

 

I would think that if the noise were present at the time of service they would have mentioned it to you, but as stated, just remove the serpentine belt start the car and see if noise is present. I believe there should be no noise when belt removed.........................but in my lifetime I've been wrong before sorry to say, not often, but it happens.

 

Belt tensioner for the drive belt, not the t-belt one.