From the Super Mario Wiki
Kazumi Totaka (戸高 一生, born August 23, 1967) is a Japanese music composer for Nintendo, and mainly works with Nintendo EAD. He has done the musical score to many games, including Super Mario Land 2: 6 Golden Coins, Mario Paint, Yoshi's Story, and many more. He is also very popular for doing the music to the Animal Crossing series. He also does the voice of Yoshi since Yoshi's Story, Professor Elvin Gadd since Luigi's Mansion and Birdo since Mario Golf: Toadstool Tour. He also did Shy Guy and Fly Guy until Nate Bihldorff took over in Mario Power Tennis. In addition, he provides the voice of Captain Olimar starting in Pikmin 2; his voice clips are reused for Olimar's Mystery Mushroom costume in Super Mario Maker.
In most games that Totaka has composed for, he has sneaked in a short, nineteen-note song commonly referred to as Totaka's Song. This song is usually hidden, only able to be heard after meeting certain conditions. The Mario games it has been spotted in are: