Panagopoulos, Costas & Donald P. Green (Published online August 16, 2010), "Spanish-Language Radio Advertisements and Latino Voter Turnout in the 2006 Congressional Elections: Field Experimental Evidence," Political Research Quartely, doi: 10.1177/1065912910367494.
Because Hispanic voters are seldom targeted for campaign communication and because they listen to radio at higher rates than non-Hispanics, Spanish-language radio represents an attractive venue for testing whether nonpartisan mass media messages can mobilize voters. We conducted a large-scale, national field experiment testing the impact of nonpartisan Spanish-language radio advertisements on Latino voter turnout in the 2006 congressional elections. The experiment, encompassing 206 congressional districts, indicates that nonpartisan radio ads represent an effective and cost-efficient means of raising Latino turnout in federal elections.
Link to article here.