Affricate Identity Crisis

In my last post, I talked about how /tr/ and /dr/ are often pronounced as [ʧr] and [ʤr], and asked why this might happen. But I forgot to write about the question I’m actually more interested in.

Here’s the deal. Suppose there were no writing system for English, and a phonologist were inventorying its sounds. Here’s one line of thinking they might follow:

“All right, I’ve established that this language has /t/ and /d/ in its consonant inventory. I also know that its other stop consonants, /p, b, k, g/, can form clusters with /r/, in words like pro, bro, crow, and grow. But for some reason, I haven’t found any words with a /tr/ or /dr/ cluster. However, I do find words with [ʧr] and [ʤr] clusters, and [ʧ] and [ʤ] are phonetically similar to [t] and [d].

“I suspect that [ʧ] and [ʤ] are /t/ and /d/ in disguise. An affrication rule is at work, such that /t/ and /d/ are pronounced as their corresponding affricates before /r/.” This is standard phonological reasoning: /t/ and /d/ are said to be phonemes, with [ʧ] and [ʤ] as possible pronunciations (i.e. allophones). But wait — now we’re left with the question of why /ʧ/ and /ʤ/ never form clusters with /r/. To put it another way, why is it that whenever we hear [ʧr] or [ʤr], we always perceive it as /tr/ or /dr/? Aren’t there any [ʧr] or [ʤr] clusters that really are /ʧr/ and /ʤr/, not /tr/ or /dr/ in disguise?

Let’s lay that aside and look at another line of thinking a phonologist might follow: “All right, I’ve established that this language has /ʧ/ and /ʤ/ in its consonant inventory, and that they can form clusters with /r/.” But now, if words like chry and jry really do begin with /ʧ/ and /ʤ/, not with /t/ and /d/ in disguise, then we’re left with a gap in the distribution of /t/ and /d/ that we noted before: Why don’t they ever occur before /r/?

For those of us who can read (and if you’re reading this, I’m guessing you can read), the spelling is the biggest clue that [ʧr] and [ʤr] are /tr/ and /dr/ in disguise: We write try and dry, not chry and jry. But how do toddlers, who for the most part can’t read, come to this conclusion? Herb Stahlke, in a comment on my last post, noted some acoustic differences between the [ʧ] and [ʤ] that you get as a result of this kind of affrication, and the [ʧ] and [ʤ] that exist independently, so that may be part of it. Or (my guess), it’s just that the gap in distribution you get when you disallow /tr/ and /dr/ clusters stands out a lot more than the one you get when you disallow /ʧr/ and /ʤr/ clusters. If you didn’t allow /tr/ and /dr/ clusters, then /t/ and /d/ would be conspicuously absent among all the other stop and fricative consonants that can form clusters with /r/, as well as with /l/. In contrast, /ʧ/ and /ʤ/ are the only affricates English has, so they don’t stand out as the only members of some class that don’t do whatever. Furthermore, they can’t form clusters with /l/, either — there are no words like *chloop or *jlick — so not forming clusters with /r/ is no big deal. The child can simply conclude that affricates don’t form clusters in English.

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