In a 1999 commentary with the game's composer Koji Kondo published in the GSLA archive, he stated that when "Ocarina" became the game's title, he decided to try and build the music around one central ocarina melody. Given that the ocarina only has five notes to play, he tried to write the various background themes in different genres (bolero, serenade, etc.) where each one would evoke a "catchy, memorable 3-note ocarina melody". This was the motif around which he created various simple, but distinct melodies, and was very careful to make sure he didn't repeat himself. Kondo then commented:

"Game music is different from other genres in that it exists to make the game more enjoyable. In addition, there's a lot of interactive things you can do with game music, which I think is one of its defining traits. A very simple example would be the way the tempo increases when a time limit is running out."

Kondo also stated the Hyrule Field theme is the main central song, and that he wrote it so that each time you play it, the song structure unfolds in a slightly different way. He also stated that when Link stands still for a while, the song will change to a more relaxed melody, and when enemies come close, the song will get tenser. Since it is a very long game, he tried to think of ways to keep the players from getting bored, and how to make the music evolve with what's happening on-screen. He hoped to continue pursuing this idea for interactive music in future games.
Contributed by ProtoSnake