Babies as young as 5 months develop quite satisfactory reasoning power, and are capable of distinguishing between various tunes, whether it is “Ode to Joy” from Beethoven's Ninth Symphony, or a sad and depressive one

This was concluded through an experiment conducted by the researchers, in which the babies were exposed to an emotionally-neutral face, while the music played. The music would stop when the baby would look away from the face and instead another sad song would start playing. 

The babies looked at the face for three to four seconds more, when the happier “Ode to Joy” was played, which suggested that the babies were keen in the shift. 

The babies were capable of doing exactly the opposite when they reached the age of 9 months, where they could pick out the sad sounds of Beethoven's Seventh Symphony from a set of happy pieces. 

This finding also indicates towards of how babies make sense of their surroundings long before they have started talking. 

According to Brigham Young University psychology professor and study author Ross Flom, “One of the first things babies understand communicatively is emotion, so for them the melody is the message. Our study showed that by nine months, babies are categorizing songs as happy or sad the same way that preschoolers and adults do.”

The upcoming issue of the journal Infant Behavior and Development will display the results of the musical study.