A new contraceptive for men on the horizon? Just a couple of zaps of ultrasound kills sperm, say scientists

-High frequency sound waves found to cut sperm rates in rats

-Further studies are required to determine how long the contraceptive effect lasts and if it is safe to use multiple times

http://www.dailymail.co.uk/health/article-2093722/Male-contraceptive-Zap-ultrasound-kills-sperm.html