During the Voyager 1 spacecraft flyby of Titan on November 12, 1980, an intense band of low-frequency electric field noise was observed during the inbound wake crossing. This analysis shows that the noise is generated by a beam-plasma interaction between the corotating magnetosphere of Saturn and newly created ions from the atmosphere of Titan. The analysis is based on plasma and wave measurements from Voyager 1 and reasonable assumptions. The results agree quite well with the observation. The analysis shows that the instability only occurs where the density of the corotational ions is comparable to the density of ions originating from Titan's atmosphere. The growth rate is high enough to generate the observed noise, and the calculated and observed frequency ranges are in good agreement. The asymmetry between the intensities in the inbound and outbound wake are explained by a simple model for the trajectories of ions from Titan's atmosphere. ¿ American Geophysical Union 1987