A vocal tract model for an American English /l/ production with lateral channels and a supralingual side branch has been developed. Acoustic modeling of an /l/ production using MRI-derived vocal tract dimensions shows that both the lateral channels and the supralingual side branch contribute to the production of zeros in the F3 to F5 frequency range, thereby resulting in pole-zero clusters around 2-5 kHz in the spectrum of the /l/ sound.