Just about six months ago SexFeed reported on some promising new methods of male birth control and one of those we mentioned is looking better after further study: a testicular zap with ultrasound.

The BBC reports that the method is being studied by University of North Carolina researchers who got a grant from the Bill and Melinda Gates Foundation and who found that two 15-minute doses of sound waves, especially if delivered through warm salt water, “significantly reduced” the number of sperm-producing cells and sperm levels.”

Quite a lot more reasearch is needed on this potential contraceptive method, mainly to find out if multiple doses are safe, to make sure it’s reversible (and doesn’t cause sterilization) and to make sure that when sperm production resumes the sperm isn’t damaged.

Newser reports that the ultrasound method was first tried out in the 1970s “when cancer patients due to have their testicles removed underwent the treatment and reported no pain, only a “gentle feeling of warmth.”

We get a gentle feeling of warmth just thinking about improvements in male contraception. Anyone else?