A study conducted by a team of Spanish researchers has shown that fetuses in the womb can start to hear and respond to the voices around them as early as 16 weeks. The researchers came to the conclusion based on their observation of the reaction of the fetuses to the music played outside the womb of the mother.

Previously, it was thought that the auditory system of the growing baby inside the womb starts to function at the age of 26 weeks. However, the latest study conducted by a team of researchers at the Institut Marqués and university of Barcelona shows that even 16-week-old fetuses can hear and respond to music.

During the study, the researchers exposed the babies to the effective and distortion-free music with the help of a musical tampon inside the mother's vagina. The team captured a series of 3D images showing fetuses responding to the music.

The images show babies opening and closing their mouth and sticking out their tongue in response to the type of music played. The researchers recorded the movement of the fetuses carried by 100 pregnant women and discovered that 87 percent of them responded to the music.

"We have discovered that the formula for fetuses to hear like us is to emit music from the mother's vagina," said Dr Marisa L pez-Teij, the lead study author. "They barely hear the sound that reaches them through their mother's abdomen because the soft tissues of the abdomen and the inside of the mother's body absorb the sound waves."

The research team believes that musical stimulation helps speed up vocal development in the babies.

"We believe that the music induces a response through vocalization movements because it activates brain circuits that stimulate language and communication," said researcher Alberto Prats of the University of Barcelona.

The complete details of the study have been published in the British journal Ultrasound.