Pitch accent is a linguistic term for a variety of methods of giving prominence to an accented syllable or mora of a word, using variations in pitch (frequency). The placement of this accent, and in some cases also the way it is realized, can give different meanings to otherwise similar words.
Pitch accent is in some sense intermediate between stress-accent languages like English and tone languages like Chinese.
Firstly, while the primary indication of accent is pitch (tone), there is only one tonic syllable or mora in a word, the position of which determines the tonal pattern of the whole word. This is unlike the situation in tone languages, where the tone of each syllable can be independent of the other syllables in the word. For example, comparing two-syllable words like [aba] in a pitch-accented language and in a tonal language, both of which only distinguish low tone from high, the tonal language has four possible patterns: low-low [àbà], high-high [ábá], high-low [ábà], low-high [àbá]. The pitch-accent language, on the other hand, only has two possibilities: accented on the first syllable, [ába], or on the second, [abá].
Secondly, there may be more than one pitch possible for the tonic syllable. For example, the pitch may be either high or low. In stress-accent systems, there is no such variation: accented syllables are simply stressed. In addition, many words may have no tonic syllable at all, whereas normally in stress-accent languages every lexical word must have a stressed syllable.
In a wider and less common sense of the term, "pitch accent" is sometimes also used to describe intonation, such as methods of conveying surprise, changing a statement into a question, or expressing information structure (topic-focus, contrasting), using variations in pitch. A great number of languages use pitch in this way, including English as well as all other major European languages. They are often called intonation languages.

In Indo-European languages
Serbo-Croatian (Serbian, Croatian and Bosnian) has four types of pitch accent: short falling, short rising, long falling and long rising. The long accents are realized by pitch change within the long vowel; the short ones are realized by the pitch difference from the subsequent syllable. Short rising accent resists such shift better than the falling one (as seen in the example /ʒěli:m/→/ne‿ʒěli:m/)

In Serbo-Croatian
Most dialects differentiate between two kinds of accents. Often referred to as acute and grave accent, they may also be referred to as accent 1 and accent 2 or tone 1 and tone 2. They are described as tonal word accents by Scandinavian linguists. Hundreds of two-syllable word pairs are differentiated only by their use of either grave or acute accent. Accent 1 is, generally speaking, used for words whose second syllable is the definite article, and for words that in Old Norse were monosyllabic. Although also some dialects of Danish use tonal word accents, in most Danish dialects so called stød functions to the very same end.
For example in many East Norwegian dialects, the word "bønder" (farmers) is pronounced using tone 1, while "bønner" (beans or prayers) uses tone 2. Though the difference in spelling occasionally allow the words to be distinguished in written language, in most cases the minimal pairs are written alike. A Swedish example would be the word "tomten," which means "Santa Claus" when pronounced using tone 1, and means "the plot of land," "the yard," or "the garden" when pronounced using tone 2. Thus, the sentence "Är det tomten på tomten?" ("Is that Santa Claus out in the yard?") uses both pronunciations right next to each other.
Although most dialects make this distinction, the actual realizations vary and are generally difficult for non-natives to distinguish. In some dialects of Swedish, including those spoken in Finland, this distinction is absent. There are significant variations in the realization of pitch accent between dialects. Thus, in most of western and northern Norway (the so-called high-pitch dialects) accent 1 is falling, while accent 2 is rising in the first syllable and falling in the second syllable or somewhere around the syllable boundary.
The word accents give Norwegian and Swedish a "singing" quality which makes it fairly easy to distinguish them from other languages.

In Norwegian and Swedish

Main article: Japanese pitch accent See also

http://www.geocities.com/caraculiambro/Caraculiambro/Stress.html