Chondrocyte seeded scaffolds were cultured in an ultrasound (US) assisted bioreactor, which supplied the cells with acoustic energy around resonance frequencies (~5.0 MHz). Polyurethane-polycarbonate (BM), chitosan (CS) and chitosan-nButanol (CSB) based scaffolds with varying porosities were chosen and the following US regimen was employed: 15 kPa and 60kPa, 5 mins/application and 6 application/day for 21 days. Non-stimulated scaffolds served as control. For BM scaffolds, US stimulation significantly impacted cell proliferation, and the depth dependent cell population density compared to controls. Highest COL2A1/COL1A1 ratios and ACAN mRNA were noted on US treated BM scaffolds compared to controls. Similar trend was noted on US treated cell-seeded CS and CSB scaffolds, but COL2A1/COL1A1 ratios were significantly lower compared to BM scaffolds. Expression of SOX9 was also elevated under US and paralleled the ratio of COL2A1/COL1A1. As an original contribution, a simplified mathematical model based on Biot theory was developed to understand the propagation of the incident US wave through the scaffolds and the model analysis was connected to cellular responses. Scaffold architecture influenced the distribution of US field; with the US field being the least attenuated in BM scaffolds, thus coupling more mechanical energy into cells, leading to increased cellular activity.