This is an anime-original, "filler" introductory episode designed to showcase alchemy and introduce the major cast immediately. It features Isaac McDougal , a "Freezing Alchemist" trying to destroy Central City, a character who never appeared in the manga.
To achieve the hollow, echoing sound of Alphonse's armor in the dub, the production team used a digital filter, though a popular piece of trivia suggests the Japanese team originally used an actual steel cook pot suspended in front of the microphone. Key Themes Introduced Fullmetal Alchemist (Dub) Episode 1
The English dub is widely regarded as one of the best in anime history. This is an anime-original