Trill

In phonetics, a trill is a consonantal sound produced by vibrations between the active articulator and passive articulator. 

Trill - A sound used in speaking

A trill is a sound that is made when pronouncing a consonant in such way that the sound produces a kind of vibration within the speaker's mouth. It is an important sound in some languages but a not highly relevant one in others. 

When a speaker produces a trill, it can be recognized by a kind of purring sound: that is the sound of the trill itself vibrating within the mouth of the speaker.

There are different classifications of the trill, depending on how exactly the mouth moves in order to produce the specific characteristic sound of the trill. 

Using trill in English and Spanish

The most familiar example of the trill for Americans is probably the "rr" sound in the Spanish language. (This trill can be found, for instance, in the Spanish word for dog: "perro".) When pronouncing this sound, the tongue of the speaker rises up in such a way that the sound is held for a moment and vibrates within the speaker's mouth. 

To the listener, this probably sounds like a kind of purring this is a good analogy for the kind of sound that is supposed to be produced by the trill. It is a distinctive sound that can only be produced by moving one's tongue in the relevant way. 

A good rule to remember for the trill is that it actually sustains in time for a moment; it is a distinct sound that has its own duration. This makes it different from the flap, which involves a similar tongue movement but has no duration of its own. 

Difficulty with native English speakers

Interestingly, the trill is probably one of the main sounds that gives native English speakers real trouble. This can be seen, for example, in any introductory course in the Spanish language, where many students may try and often fail to pronounce the purring "rr" sound that can be found in words such as "perro". The trill is thus quite foreign to the English language, and it is quite likely that a native speaker may not have learned how to properly pronounce the sound in a natural way as a child. After all, there would have been no reason for the child to learn how to pronounce the word. 

This point also calls attention to the value that can be found in consciously studying and becoming aware of linguistic concepts such as the trill. The trill is characterized by a very specific kind of movement of the mouth and tongue. So, if the native English speaker is not intuitively or subconsciously familiar with the movement of the trill, then consciously studying it may help him pronounce the sound in a more effective way.

This is one way in which the study of concepts such as the trill can be of more than merely theoretical interest to professional linguistics. Rather, better understanding the mechanics of the trill could actually help a speaker figure out how to produce a trill.