Trans-abdominal vocalization
Trans-abdominal vocalization was The Doctor's term for the practice of transmitting one's voice into the abdomen, more specifically, the womb, of another, via a diatonal amplifier. This was done in order to benefit an unborn baby.

In 2377, as part of a prenatal enrichment program, The Doctor planned to perform trans-abdominal vocalization for the benefit of B'Elanna Torres and Tom Paris' unborn baby. Upon hearing of his plans, B'Elanna quipped, ": Let me guess. You're going to sing to my fetus." The Doctor assured her the practice was safe and could increase the child's skill at mathematics. ()
Medical procedures