In linguistics, the timing in a language comprises the rhythmic qualities of speech, in particular how syllables are distributed across time. There are two basic ways to assign time units (or beats) to words: stress timing and syllable timing. Linguistics is the scientific study of human language, and someone who engages in this study is called a linguist. ... This article discusses the unit of speech. ... In linguistics, stress is the emphasis given to some syllables (often no more than one in each word, but in many languages, long words have a secondary stress a few syllables away from the primary stress, as in the words cóunterfòil or còunterintélligence). ...

In a syllable-timed language, every syllable takes up roughly the same amount of time when pronounced, though the actual length of time of a syllable depends on situation. Spanish and Japanese are examples (more accurately, Japanese is mora-timed rather than syllable-timed, but the basic concept is the same). This metronomic rhythm is sometimes called machine-gun rhythm. When spoken faster, a syllable-timed language uses a faster rhythm to carry more syllables in a second. Mora (plural moras or morae) is a unit of sound used in phonology that determines syllable weight (which in turn determines stress) in some languages. ...

In a stress-timed language, syllables may last different amounts of time, but there is a given amount time (on average) between two consecutive stressed syllables, and that time is roughly a constant. English, German and Dutch are typical stress timed languages. Stress-timing is sometimes called Morse-code rhythm. When spoken faster, a stress-timed language usually shortens, obscares, or drops vowels to carry more syllables between two stresses without changing its rhythm so much. The English language is a West Germanic language that originates in England. ...

This difference comes from the human's two senses of rhythm. When we hear a fast rhythm, typically faster than 330 milliseconds (ms) per beat, we hear it as a whole. We can imitate a machine gun sound, but we can hardly count its beats. On the other hand, when we hear a slow rhythm, typically slower than 450 ms per beat, we hear each beat separately. We can easily control the speed of slow rhythm beat by beat, such as hand clapping in music. If a language has a simple syllable structure, the differance between the simplest and the most complicated syllables in the language is not wide, and it is possible to say any syllable in less than 330 ms. Thus we can use the fast syllable-timed rhythm. If a language has complex syllables such as ones with consonant clusters, the difference between syllables can be very wide, such as a and strengths in English. In this case, we have to use the slow stress-timed rhythm. A millisecond is an SI-derived unit of time, equal to one thousandth of a second. ... In linguistics, a consonant cluster is a group of consonants which have no intervening vowel. ...

Of course these patterns can change over time or be borrowed from other languages. For example, Mexican Spanish, due to close contact with American English, shows a marked tendency towards stress timing. There are reports of Mexican people pronouncing "los Estados Unidos" as two "syllables", which actually means the speaker marks two beats or stress peaks (over /ta/ and /ni/), in the same way that e. g. an Argentine Spanish speaker would mark the two syllabic peaks in a word like "pompón". The pervasive vowel reduction and shortening found in English is in part a consequence of stress timing; Mexican Spanish under this influence shows signs of vowel shortening as well. Mexican Spanish is the form of the Spanish language spoken in Mexico by over 90% of the population. ... American English (AmE) is the form of the English language used mostly in the United States of America. ...

References

• Kono, Morio. (1997). "Perception and Psychology of Rhythm." Accent, Intonation, Rhythm and Pause. (Japanese)