A pocketed spring assembly comprises a plurality of parallel strings of individually pocketed springs. Each string is joined to at least one adjacent string. Each string has first and second opposed plies of fabric and a plurality of pockets formed along a length of the string by transverse segmented seams joining the plies. Gaps between the segments of the seams allow air to pass into and out of the pockets despite the fabric being impermeable to airflow through the fabric. The size of the gaps determines the firmness or “feel” of the pocketed spring assembly or portion thereof.