“People in the community who deal with erectile dysfunction often use the word ‘promising’ when they talk about this therapy,” says Dr. Michael Reitano, the physician-in-residence for men’s health startup Roman, the creators of the erection-tracking app Morning Glory.

The therapy is available in a handful of practices in New York City and several more nationwide. Its proponents say the sound wave pulses cause new blood vessels and nerve tissue to grow within the penis, enabling better blood flow and possibly improving tissue sensitivity.