I understand that aspirated consonants (or unvoiced stops) after 'S' are pronounced as unaspirated. For instance, STAIN is pronounced as SDAIN, EXTEND is pronounced as EXDEND.

However, for the word SIXTEEN, there seems to be inconsistencies. According to http://dictionary.cambridge.org/dictionary/british/sixteen?q=sixteen , the American version of SIXTEEN is pronounced with an aspirated T. Why is that? Are there any other similar words?

Is there a list of such rules and exceptions available out there?

  • Stain is pronounced /steɪn/, not /sdeɪn/, but Italy is pronounced /ˈɪdəli/. Sixteen is pronounced /ˌsɪkˈstin/, similarly to foxtail that is pronounced /ˈfɑksteɪl/. (That is what the NOAD says.)
    – apaderno
    Aug 14, 2013 at 14:53
  • @kiamlaluno I'm not talking about IPA or any of the phonetic spelling matter. I'm talking about the actual pronunciation. Can't you hear the difference between the two versions of SIXTEEN on the cambridge dictionary page?
    – He Shiming
    Aug 14, 2013 at 14:59
  • @kiamlaluno on another note, I believe the t in ITALY is a regular t. I don't know which version of NOAD says 'd', but all of my dictionaries say 't'. However you would note that the American T is different from British T, whereas the American T is pronounced almost exactly as D. For instance, the word LITTLE is pronounced very closely to RIDDLE. Though I'm not talking about this phenomenon in this particular question.
    – He Shiming
    Aug 14, 2013 at 15:08
  • 2
    The IPA is the graphical representation of the pronunciation. As for the pronunciation used by people, that depends from where they live; for example, the cot–caught merger is evident in some regions of the USA, but not in other regions. The IPA pronunciations I reported are the ones shown by the New Oxford American Dictionary 3rd edition.
    – apaderno
    Aug 14, 2013 at 15:19
  • 1
    I think the aspirated/unaspirated "T" is a red herring here. It's more that because sixTEEN is normally differentiated from SIXty by having the stress on the second syllable, it inevitably follows that the letter "T" gets more accentuated than would otherwise be the case. Aug 14, 2013 at 21:06

5 Answers 5


All stops are ordinarily pronounced without aspiration following /s/. But if you do aspirate such a stop nobody will hear it.

In the first place, I think you are confusing aspiration and voicing.

  • Voicing is vocal chord vibration—‘hum’. In IPA notation, voiced and voiceless consonants are distinguished with different glyphs. The ‘official’ distinction between /t/ and /d/ is one of voicing, not aspiration: /t/ is voiceless, /d/ is voiced.
  • Aspiration is a brief puff of air after a stop is released, before the onset of voicing on the following vowel. In IPA notation, aspiration is notated with a superscript <h>. Aspirate [b], for instance, is notated [bh]. The specific absence of aspiration, as snailboat tells us, may be notated with =: [t=] is unaspirated [t]. At the site you link to it is the UK pronunciation which bears a detectable degree of aspiration; the US pronunciation has little or none.

In the second place, I think you are confusing phonetic phenomena with phonemic phenomena.

  • Phonetic sounds are phones, the physical sounds which people actually produce. They cover an infinite range; every individual has their own characteristic pattern of sounds, and every one of their utterances is slightly different. Phonetic transcriptions are conventionally presented in square brackets, thus [t], [th], [d], [dh].
  • Phonemic ‘sounds’ are phonemes, linguistic abstractions; these represent the sounds which people intend and hear and recognize. By way of analogy: the letter A takes many different forms, but they are all recognized as A:
    enter image description here
    Phonemic transcriptions are conventionally presented in slashes, thus /t/. This is the sort of transcription that shows up in dictionaries: a transcription which tells you not the actual sounds, but the meaningful sounds.

In English, aspiration is not phonemic. That is, aspiration does not consistently distinguish one English phoneme from another. Whether or not a consonant is aspirated is determined almost entirely by the sounds which surround it, its context, and that context is predictable. Consequently, aspiration does not add any meaning, which is why it is not marked in dictionary pronunciations.

However (and this is where it gets tricky), aspiration is called into play to assist in phonemic distinction in some contexts—specifically, in distinguishing syllable-initial voiced and voiceless stops.

This is because when you come right down to it, there is no such thing as a ‘voiced’ stop. A stop, by definition, completely interrupts the flow of air, and without air passing over the vocal chords there can be no voicing. With /t/ and /d/, for instance, which are articulated identically, there is no actual difference on the consonant itself. What we call a ‘voiced’ stop is in fact usually recognized mostly by ‘extra’ voicing before the air flow is stopped—typically, the preceding vowel is pronounced longer or even turned into a diphthong.

But this doesn’t work when there is no preceding vowel—at the beginning of a syllable. Since we cannot mark the voiced stop here, we mark the voiceless stop instead, with aspiration. Aspiration is not voiced (there is no hum on the air which is released), so the voicing on the vowel is delayed. The discernible difference between the aspiration which belongs to the consonant and the voice which belongs to the vowel marks the consonant as voiceless.

(But you should not take this to mean that native speakers ‘hear’ the aspiration. They don’t. What they ‘hear’ is /t/ rather than /d/.)

Why then are voiceless stops not aspirated after /s/ at the beginning of a syllable? Because they don’t have to be. The clusters /sb/, /sd/, /sg/ do not exist in English. If you hear /s/-plus-dental-stop it cannot be /sd/; it cannot be anything except /st/, so there is no need for aspiration to resolve an ambiguity.

As for your specific question: What people hear is phonemes, not phones. You may pronounce as [sɪk·st=iːn] or [sɪk·sthiːn] or [sɪk·sd=iːn] or even as [sɪg·zdhiːn] and nobody will notice. What they will hear is /sɪk·stiːn], because that’s all they know how to hear in that context, and that’s all that makes sense.

There are of course cases like iceberg and misdeed; but there we have adjacent sounds at the boundary between two distinct morphemes. It is only spelling convention which makes misdeed a single word.

  • 1
    Do some people distinguish between "sixteen" and "sixty" by aspirating the "t" in "sixteen"? I believe I do, and this might explain why some Americans aspirate it. (Of course, my aspirating it doesn't help if nobody else does). Aug 15, 2013 at 0:07
  • 1
    @Peter: In BrE, thirty-six tea cups contain a three dozen refreshing hot beverages. But thirty-six 'D' cups contain a pair of something completely different! :) Aug 15, 2013 at 1:39
  • Thank you so much for the detailed explanation. You are right I didn't get the difference between a phoneme and a phone. I'm working on a pronunciation scoring system which needs to identify whether [t] or [t=] is actually spoken. For ESL learners, this is a major problem simply because the IPAs are telling them to use [t] exclusively (which I believe is easily discernible BTW). @FumbleFingers mentioned a pretty interesting point (good one :) that an emphasized [t] happens when there will be confusion.
    – He Shiming
    Aug 15, 2013 at 3:00
  • There certainly is such a thing as a voiced stop—many languages have them. A stop means that the flow of air is fully interrupted somewhere, but not necessarily in the glottis, which is the only place that directly affects voicing. For English /d/, the phonemic interruption happens at the alveolum, but the complete closure of the glottis is incidental; French, for example, sustains voicing throughout voiced plosives, as do some speakers of English (post-vocalically more commonly than syllable-initially). Aug 15, 2013 at 4:45
  • 2
    Something that this answer does not mention, but which is highly significant I think, is that ‘sixteen’ (like ‘iceberg’ and ‘misdeed’) also has the /t/ at the head of the initial, stressed syllable of a distinct morpheme. The morphophonemic syllable boundary is /siks.tiːn/, not /sik.stiːn/. The fact that ‘sixteen’ is often heard with an unaspirated t is simply due to the fact that the s is perceived as ambisyllabic. Both pronunciations are equally natural to me (though the aspirated version is more emphatic), which is not true for ‘bestow’, for example, where the t is not syllable-initial. Aug 15, 2013 at 4:55

Interesting question! I had to think about it a bit.

It isn't so much that they are replaced by their aspirated correlate as that the aspiration is somewhat attenuated in fast speech. The "t" in "stain" is not quite the same as the (second) "d" in "disdain", for example, unless you are speaking very quickly.

What you are hearing is most typical in syllables (1) beginning with consonant blends (st, sp), where (2) the first consonant is an unaspirated fricative and the second one is an unaspirated plosive, (3) the syllable is accented, and (4) the syllable is either the first syllable in the word or is preceded by an unaccented syllable. The point about "sixteen" is that both syllables are accented (which is rather rare). This is why it is different from "extend". To take another example, you'll find that "espouse" sounds a bit like "esbouse" for the same reasons.

  • Thank you. I think the minute difference between T and D can be ignored though. Could you provide any citations for things you mentioned in the 3rd paragraph?
    – He Shiming
    Aug 14, 2013 at 22:54
  • Citations? No, I'm sorry, that's my own analysis. I didn't read it anywhere.
    – BobRodes
    Aug 22, 2013 at 0:26

"T" is aspirated in sixteen given that the vowel which follow it is stressed; it means it is aspirated even placed after /s/ sound. Rules have some exceptions. On the other hand not only consonants, but also vowels can suffer a little variation depending on the sound which follows them; for instance in "bad and bat", both words have the same vowel, however "a" is more extended in "bad" because it is followed by a voiced sound.

  • Thank you for the insight on vowel situations. It appears that this phenomenon happens to only American English. The British won't extend 'ae' in 'bad', will they?
    – He Shiming
    Jan 25, 2014 at 1:53

Hmm, I don't think that rule is correct. I pronounce "stain" with an unaspirated "t". thefreedictionary.com gives the pronunciation as "stan" (with a long a) and if you click the "say it" icon it sounds unaspirated to me.

"extend" seems borderline to me, but I'd say that's still unaspirated.

I pronounce "Italy" as "idilee", but I've heard it both ways.

But yes, "little" is pronounced "liddel", hard-d.

I don't know what the rule is on when t is soft versus hard, but the "after an s it's hard" isn't correct.

  • Thanks for the answer, but you didn't mention SIXTEEN, and whether there are other cases where aspirated and unaspirated are both acceptable. Because it's clearly not acceptable to pronounced an aspirated T in STAIN.
    – He Shiming
    Aug 14, 2013 at 15:26
  • "Sixteen" is, to the best of my knowledge, always pronounced with a soft "t". As to the general case, well, I thought I did give my answer to that: To quote Mark Twain, I gave a complete and accurate answer. I said, "I don't know."
    – Jay
    Aug 15, 2013 at 18:48

I agreed with everything up until "Why then are voiceless stops not aspirated after /s/ at the beginning of a syllable? Because they don’t have to be." Other languages and other accents do not distinguish paired stops via aspiration (that is, there may be a phonemic difference as in Hindi), and I don't believe volition or agency of the speaker plays a role (as if it were only a case of "they could aspirate if they wanted to"). Rather, I think there is a physical reason why we don't aspirate in, eg, "scat" as opposed to in "cat." In normal running speech, the sibilant /s/ itself involves a release of air, and it is the vast majority of the air available before the vowel for that consonant blend [sk]. In stylized (non-natural) speech we can hear this doesn't work because we may be drawing out the [s] and the flow continues with the velar stop [k], but if we were to hold the [s] long enough to essentially empty our lungs, that residual aspiration we hear in stylized speech is no longer present, just as in natural speech. Now, distinguishing between American English and other languages/dialects is important, because AE, as you noted, doesn't require the difference in aspiration, but the question is not fully answered without looking at the physical articulation itself.

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