The research in this area is significantly out dated. I am currently doing research to find the answer to this question. The studies I have found that address this question are from 1990,1992,1994. All of the research has small sample sizes and the results at those times showed listening was not very prevalent as a course offered. Most listening was taught as a unit in another course. Mostly listening instruction is found in Speech Communication courses. The time spent with listening was between three and five hours.
Perkins, T. M. (1994). A survey of listening instruction in the basic speech course. International Journal of Listening, 8(1), 80-97. doi: 10.1080/10904018.1994.10499132
Wolvin, A. D., Coakley C. G., &. Disburg, J. E. (1992). Listening instruction in selected colleges and universities. International Listening Association Journal. 6:1, 59-65 doi:10.1080/10904018.1992.10499108
Wolvin, A. D., Coakley C. G., &. Disburg, J. E. (1990). The status of listening instruction in American colleges and universities. International Listening Association Journal.