A trickle vent such as might be used in association with commercial windows is formed from PVC tubing in two convoluted paths. One or more expansion chambers are provided at turns or directional changes within the tubing which reduce or eliminate noise transmission through the vent. Where a plurality of expansion chambers are used, each chamber may be of different length to dampen a different portion of the acoustic spectrum. In a preferred embodiment, the expansion chambers are filled with an acoustic-type foam, and the ends are not completely sealed. The tubing preferably bridges two extrusions that form a supporting housing for the vent, and by using two separate extrusions bridged by the tubing, both thermal and acoustic isolation are maintained.