Not to be confused with high rising terminal or "uptalk," rising inflection generically refers to any time a speaker's vocal pitch increases in frequency, and it specifically refers to the way vocal pitch rises at the end of interrogative sentences, in several widespread stressed languages.
In English, a question is differentiated from a statement grammatically by a shift from subject-verb-object word order to verb-subject-object word order, and by the inclusion of a "question" word such as "who" or "where." Most regional variants of English also indicate a question through the use of steeply rising vocal pitch at the very end of the question, usually on the last stressed syllable in the sentence, or the very last syllable (even if it is unstressed) in some instances. Examples of this follow, with raised pitch shown as capitalization.
Declarative statement: The car is in the garage.
Question: Is the car in the gaRAGE?
Declarative statement: I want a soda.
Question: Do you want some soDA?
(Note here that the 'so' of 'soda' would typically be more stressed than the 'da,' but the rising pitch is on the unstressed 'da.')
English is not the only language which indicates interrogation through rising pitch. Pashto and Russian both use upward inflection; in Pashto, the upward inflection will often be the only way to determine if a sentence is declarative or interrogative, because word order shifts and "question words" are not necessarily incorporated.
In Japanese, rising inflection for sentences is commonly used to replace question words completely.
"Ano hito wa nihonjin desho ne?"
has the same meaning as
"Ano hito wa niHONJIN?"
This complete replacement of question words does occur also in many regional forms of English, but it also tends to create a nuanced difference in meaning:
"Does Jane want to go to the PARK?"
has a related but not identical meaning to
"Jane wants to go to the PARK?"
In the former case, the speaker might be asking where, of many possible places, does Jane wish to go. In the latter case, the speaker may be expressing distaste or disbelief for the fact that Jane specifically wishes to visit the park; the second question can also be interpreted easily as a rhetorical question, while this is unlikely for the first.
It is worth noting that rising inflection in sentences is not universal to all languages: for most tonal languages, it is essentially nonexistent, because a rising pitch could completely change the meaning of any single word. It is also not inherently present in every stressed language, but due to a great deal of international contact and the sheer number of bilingual households in the world, rising interrogative pitch has migrated into languages which did not previously include it. It is recommended that anybody learning a new stressed language take care to learn if native speakers use rising pitch, because using it mistakenly can leave you sounding like that language's equivalent of a Valley Girl.