The use to which a language puts pitch determines whether it is a tone language or a non-tonal one. In Pike’s famous definition of a tone language (1948), we are told that a tone language is one that makes significant use of pitch on every syllable. By this definition, it is to be expected that pitch differences in individual syllables may be lexically or even grammatically significant. Lexical use of pitch is seen in Yoruba:

These examples show that a variation on a syllable can cause a change in lexical meaning. In (4) and (5) from , a North-central Edoid language of the Benue-Congo family in Edo State of Nigeria, we find that a similar change in the pitch of a syllable results in a change of grammatical meaning:

It should be noted that the case for the significance of pitch on every syllable is still valid even where these minimal pairs or sets do not exist – provided a change of pitch leads to some kind of change, including to an unacceptable (i.e. meaningless) utterance. Mafeni (1971) subjected NigP to this test and concluded that it is a tone language with two tones (low and high) because of lexical examples cited below:

Mafeni also suggested what might be called a tone rule by which monosyllabic high-tone words are realized on a falling pitch pre-pausally. Sentences (6) and (7) exemplify such falling pitch:

However, the way NigP uses pitch does not fit that of a tone language. In languages such as English, pitch variations cover whole phrases, clauses or sentences. Moreover, pitch variations do not alter the basic lexical composition of an utterance. Thus the word ‘Yes’, said with a variety of pitch variations, remains ‘Yes’. This type of language is called an intonation language. English, from which NigP is derived (it is NigP’s superstrate), also operates a stress system and there is some evidence that NigP equates stress with high pitch. For example, tense and aspect markers are not normally stressed in English: similarly in NigP, such markers are not said on a high pitch whereas full verbs are (compare 8a and c, as well as 8b and d):

There seems little doubt that NigP employs pitch for intonation along lines similar to what English does. For example in sentences 8(a)–(d) above intonation differences can change a statement into a question:

Note that the high of (9a) is even higher or still rising in (9c) while the falling high of (9b) now lacks a fall and is even higher and rising.

Elugbe and Omamor (1991: 85) suggest that NigP is something of a pitch-accent language in which, given a word there may be only one high tone, or one sequence thereof in opposition to one low sequence:

Exceptions to the above pattern are words taken directly from local languages and not adapted into the NigP sound system. Elements of a similar analysis are to be found in Mafeni’s suggestion that high-tone syllables in NigP are normally more heavily stressed than low-tone ones. In other words, the high tone may be correlated with (strong) stress while the low tone is correlated with weak stress (or a lack of it?). However, in a word such as miraku for example there are three pitch levels of which the first is the highest and the last is the lowest. The same applies to the word  in which the pitch descends from the high of  through the mid of ri to the low of ti. Such examples show that after the accented syllable, a kind of ‘downdrift’, such as characterizes statement intonation in English, occurs also in NigP. That is the reason that Mafeni claimed that the intonation of NigP is very similar to that of English.

Another issue raised by Mafeni is of rhythm. He describes NigP as a “syllable-timed” language in which “The syllables constituting a stretch of utterance occur isochronously and tend to be of equal duration” (1971: 109). In this respect as in Nigerian languages which form the substrate for NigP, every syllable is as prominent as the other and the weakening of syllables as we see in a stress language such as English does not occur.