Expectant parents are often told to start speaking to their unborn child about 23 weeks into the pregnancy as that's when the fetus can hear voices and other sounds. But a new study by Spanish researchers shows a fetus' hearing ability to begin much earlier - at just 16 weeks. Emitting music through a special device inserted in the mother's vagina, the researchers from Institut Marquès, a gynaecology and fertility clinic in Barcelona, found that fetuses heard and responded to the musical stimulus by opening their mouths and pulling their tongues out as far as possible, making vocalisation movements. “We have discovered that the formula for fetuses to hear like us is to emit music from the mother’s vagina. They barely hear the sound that reaches them through their mother’s abdomen: the soft tissues of the abdomen and the inside of the mother’s body absorb the soundwaves," says Dr Marisa López-Teijón, the head of assisted reproduction at Institut Marquès and the principal researcher and author of the study published this week in the British Medical Ultrasound Society journal Ultrasound . The researchers say the music emitting device, which was specially developed for the study, enables fetal deafness to be ruled out. It also makes ultrasound scans easier and reduces the stress of parents during pregnancy. "For the first time, we have been able to communicate with the fetus. From the 16th week, it is capable of responding to musical stimuli," says López-Teijón. "We can say that learning begins in the womb." In the study, the chosen music - Partita in A Minor for Flute Alone – BWV 1013 by Johann Sebastian Bach - was emitted at an average intensity of 54 decibels, the equivalent of a quiet conversation or background music. Using ultrasound scans, the research team compared the reaction of the fetuses and found the results to be statistically significant. When music was applied from the vagina, 87 per cent of fetuses moved their mouths or tongues and approximately half of them reacted with a very noticeable movement, opening their jaws very wide and pulling out their tongues as far as possible, says Dr. Alex García Faura, Institut Marquès' scientific director and co-author of the article. On applying music emitted through the abdomen or soundwaves, these changes in the expressions of the fetuses were not observed. "We believe that the music induces a response through vocalisation movements because it activates brain circuits that stimulate language and communication," says Alberto Prats, the professor of anatomy and human embryology of the Faculty of Medicine of the University of Barcelona. According to this hypothesis, once the formation of the inner ear is complete, when the fetus receives an auditory stimulus that includes rhythm or melody through the cochlea (the snail-shaped auditory portion of the inner ear), very primitive brainstem centres that induce vocalisation are activated in the area related to social behaviour.