Here are the main words for sound in German, with their specific meanings.

Klang is a pure sound that is appealing to the sense of hearing and fades with time:

Ihm gefällt der Klang dieser Gitarre. The sound of this guitar appeals to him.
Ich liebe den Klang ihrer Stimme. I love the sound of her voice.

Ton is a sound that, as opposed to Klang has no overtones (meaning, it has no additional harmonic sounds that give the overall sound warmth, for example):

Ich mochte den Ton in ihrer Stimme nicht. I didn’t like the sound in her voice.
Bitte sprechen Sie Ihre Nachricht nach dem Ton. Please leave a message after the beep.

Geräusch is a sound perceived acoustically that is produced as a byproduct of something that is moving – in other words, just like “noise” it is not made on purpose in most cases:

Du machst immer so laute Geräusche wenn du isst! You always make such loud sounds when you eat!

Schall is either a reverberating sound, or simply the word for “sound” used in Physics:

Das Flugzeug fliegt schneller als der Schall. The plane flies faster than (the speed of) sound.

Laut is like Geräusch but produced on purpose (usually using one’s mouth) and of short duration:

Er gab einen kleinen Laut von sich. He gave off a little sound.

Sound is a very popular word nowadays, but it refers specifically to the characteristic sound of a musician, band or musical style:

Diese Gruppe hat einen echt coolen Sound. This band has a really cool sound.