Based on early work, University of North Carolina experts believe a blast of ultrasound to the testes can safely stop sperm production for six months.
With a grant of $100,000 from the Bill & Melinda Gates Foundation they will push ahead with more clinical trials. The researchers ultimately hope it could offer a new birth control option to couples throughout the world. 
As Tsuruta told the BBC:
“We think this could provide men with up to six months of reliable, low-cost, non-hormonal contraception from a single round of treatment… Our long-term goal is to use ultrasound from therapeutic instruments that are commonly found in sports medicine or physical therapy clinics as an inexpensive, long-term, reversible male contraceptive suitable for use in developing to first world countries.”