An allophone is a variation of a phoneme. A phoneme, on the other hand, is a category that exists in our minds. So if we want to convey the idea of /ttt/ (phoneme), we have to choose one of the ways (allophones) to produce it. These various ways to convey each building block are the allophones. This is an important concept for cuers. Not every difference in pronunciation can (or should) be cued. Cued speech represents phonemes not allophones. So understanding the difference is important.
An an analogy, consider another category. If you were to see an apple, banana, orange, kiwi, and grapes, what category comes to mind? The concept of fruit is a category that only exists in the mind. One cannot show someone what fruit is without selecting a particular member of the category. Similarly, the building blocks, or phonemes, otf a language are categories in our minds. If you want to speak that building block to another, you select one of the ways to pronounce it. You'd like choose the /t/ found in the word top. That doesn't mean that every /t/ has to be pronounced like the /t/ in top. Further, handshape 5 represents all of the versions of /t/ not just the one that comes out when we say /mmmfffttt/.
Typically, when written reference is made to a phonemic category, slasshes surround the written symbol. For example, /t/ serves as the representation of the phoneme in words like tea, bottom, stop, and Batman. The sounds in these words can be categorized as belonging to the category /t/ eventhough they sound slightly different when pronounced. Written reference to the actual sounds as they are pronounced is usually surrounded by brackets. So for instance, the occurrence of /t/ in the word tea is represented by [ttt]. The symbol [ttt] is surrounded by brackets indicating it represents an allophone, or variation of a phoneme, and additional information is provided by including a diacritic marker in the form of a superscripted "h". This diacritic symbol serves to represent the aspirated quality of the sound as loud, turbulent air is expelled while speaking the [t]. Note that this sound at the beginning of tea is not the same as the [t] heard in the word Batman. That allophone sounds quite different and even has its own symbol [ʔ] and is called a glottal stop.
When people speak sounds in reference to phonemes, they cannot avoid choosing a single allophone to serve as an example. For instance when presenting handshape 5 and saying representations for /m f t/, teachers often represent the phoneme /t/ by saying a sound like the one at the beginning of the word "time." By doing so they link that sound, [tʰ], with handshape 5. However, some new cuers recognize that they do not say [tʰ] in other words like stop, tree, Batman, or butter. They sometimes look for alternatives to handshape 5 because they do not aspirate the /t/ in those words and believe they must somehow show that it sounds different. This, of course, is not necessary or correct.
Allophones of /t/ and Student Errors
|stop||Sounds different than [tʰ]. However, students cannot find another cue that will represent this version of /t/ and therefore cue it correctly as handshape 5.||When /t/ occurs between /s/ and a vowel, the aspiration is lost. This makes it sound different than [tʰ], but it is not cued differently.|
|tree||Sounds like "ch". New cuers sometimes want to cue tree starting with handshape 8. They will argue, "I don't say tʰ - ree!"||When /t/ occurs before /r/ its placement in the mouth changes and makes it resemble /ʧ/. The argument, "I don't say tʰ - ree!" is true, but is based on the idea that handshape 5 represents /m f/ and [tʰ] (that sound we make when we say the sounds represented by the phoneme). In reality, though, its also the handshape used in stop and hit. Students just as unlikely to say the word hit as "hitʰ" with a large puff of air at the end. Handshape 5 does not only represent [tʰ]. It represents all of the allophones of /t/.|
|Batman||Sounds like the lack of sound leading students to omit the cue.||In the word Batman, the /t/ is not produced [tʰ]. In fact, it is likely to be produced in an entirely different place than behind the upper front teeth. Instead, it is made with a constriction closer to the back of the throat. We do omit the cue, because there is a consonant there. We know its there because if you take it out, we get Baa-man. The constriction that stops the vowel is the first syllable is a consonant. That sound is a glottal stop and is one version of a /t/. There is no cue specifically for a glottal stop. Eventhough people don't say Batʰman with a puff of air in the middle, we still need a cue there and it is handshape 5.|
|butter||Sounds like /d/.||Again people go back to the argument, "I don't say butʰer!" And they're right. They don't. But again, handshape 5 represents more than just [tʰ]. This version of /t/ is sometimes called a flap and it coincidentally sounds like another phoneme: /d/. because there is another cue available that sounds like this version of a /t/, people often want to cue it as a /d/. This is generally regarded as incorrect when cueing for interpersonal communication and on expressive cueing tests.|