Pitch accent is a way some spoken languages make one syllable in a word stand out by giving it a special pitch pattern. A small rise or fall in pitch on that one syllable can change the word’s meaning, or simply make it sound “right” to native speakers.
This is different from a stress accent, which English uses. In English the important syllable is mainly louder and longer, not higher or lower.
Languages that use pitch accent include Japanese, Swedish, and Serbo-Croatian.
In a pitch-accent language, only one syllable (or mora) of a word gets the special pitch. The other syllables follow a regular pattern. Moving the accent to a different place can turn the word into another word.
Japanese shows clear pitch accent. The same sounds can mean different things depending on the accent position.
Swedish has two pitch-accent “melodies,” called Accent 1 and Accent 2. Some words are spelled the same but change meaning with a different melody.
Standard Serbo-Croatian has four pitch accents (two rising and two falling).
Pitch accent is different from a full tone language such as Mandarin Chinese.
So pitch accent can be seen as a simpler system than tone.