How can we distinguish, for example, these two sentences just by listening to the pronunciation?

  1. They first kill the trees.

  2. They first killed the trees.

When pronouncing kill the trees, we have one [d] that is for the. When pronouncing killed the trees, we have two [d] that is for killed and the.

Native speakers pronounce both sentences so that we just hear one [d], so we don't know the tense by pronunciation in these cases. Am I right?

Is there any special stress or extension of a sound that signals the difference between them?

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    While killed ends in /d/, the starts with /θ/ so there is no difficulty. If the sentence were "They killed dying trees", then there are two /d/ sounds. In that case, the first would be reduced and there's a slight but noticeable pause before the second one. – Andrew Leach Jun 12 '13 at 16:12
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    Yes, but the question is about the spelling system and how it differs from the pronunciation. And how do native English speakers differentiate, anyway, between spoken They kill the trees and They killed the trees, given that /d/ in /dð/ clusters is virtually always inaudible? – John Lawler Jun 12 '13 at 16:45
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    I think we distinguish between them the same way that we distinguish between "They first cut the trees down" (past) and "They first cut the trees down" (present). Namely, context. (Although note the consonant is not /d/ but /ð/.) – Peter Shor Jun 12 '13 at 18:48
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    @superdemongob Unfortunately, it's possible that both your pronunciation and your perception are different while you're focused on the activity of producing this sequence. – snailboat Jun 13 '13 at 14:27
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    @JohnLawler Are you sure about that? I would say that in /dð/ clusters, it's the /ð/ that's nearly always inaudible. That's the main difference for me between these two: /kʰɪɫðə/ vs. /kʰɪɫd(ð)ə/. Much harder to distinguish are “They killed the tree” and “They killed a tree”, which can be almost entirely homophonous for me. – Janus Bahs Jacquet Oct 20 '15 at 23:26

We can distinguish them because they are pronounced differently, and "-ed" is past tense. I don't see what is confusing about this.

Edited to add: I see that I may not have addressed part of your question. You wrote:

Native speakers pronounce both sentences so that we just hear one [d], so we don't know the tense by pronunciation in these cases. Am I right?

The answer is: No, you are not right. I am a native speaker and would never say "killed the" and not pronouce the "-ed". To be sure, "killed" is not prounounced with two syllables, like "kill-ed", but neither is the "d" silent. The "e" is silent, however. The pronunciation goes like this: "killd".

When I reflect upon it, I don't know why the "ed" is silent. With many verbs ending in "-ed" the "e" IS pronounced. Some examples:

  • hated
  • waited
  • extended
  • painted
  • tooted

Examples where the "e" is silent and the final "d" is not:

  • killed
  • tooled
  • pained
  • warred
  • tried

I am sure a linguist could come up with a general rule, but I'm not one of those, so I must defer to an expert. It does seem like verbs whose base ends in "d" or "t" will have pronounced "e" in their "-ed"s.

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    I was going to post a similar answer. Native speakers that don't pronounce the -ed are not enunciating. In those instances, a native speaker would determine which they meant by using context clues from the surrounding sentences. – Alex W Oct 21 '15 at 14:09
  • Mr Cyberherbalist. Have done my best to give an explanation below!! – Araucaria Oct 26 '15 at 3:58

Farid, Cyberherbalist and Drew have all given good explanations of how the words should be pronounced and that native speakers should generally hear a difference. I'd like to talk about why an English-learner might not hear that difference.

When we each learn our respective native languages, we learn to differentiate between certain sounds. The specific sets of sounds differ widely between languages, such that a learner of a new language may find that there are sounds that seem identical to the learner, where native speakers can distinguish them.

Certainly there are cases where these sounds ARE identical and even the native speaker must rely on context to differentiate between intended words, but it is also often the case that a learner's ear is not attuned to the differences between these sounds.

For example, in learning Hindi, I have had some difficulty in learning to distinguish between alveolar and retroflex sounds which to me really just sound almost identical unless the speaker is specifically trying to enunciate to show the difference. But it can be a big difference, for example, the words "fat/thick" and "pearl" are identical in Hindi apart from this precise difference. To me, they both sound like "moti", but the T sound I hear is either त (alveolar t) or ट (retroflex ṭ). To a native speaker, these sounds are quite distinctive, and let me tell you, it can be embarrassing to say "fat" when one means "pearl".

Similarly, in English we distinguish between W (/w/ - voiced labial-velar approximant) and V (/v/ - voiced labial-dental fricative), but in Hindi (and many other languages), these are used interchangeably, making it potentially hard for a native Hindi-speaker to distinguish between "vine" and "wine". Of course, clearly, since the word "wine" came from the same root as "vine", these are related sounds, but to my ear they are completely distinct and it's hard to understand how someone can hear them as interchangeable. In the same way, the Hindi speaker hears a very different sound between त and ट and has trouble understanding my difficulty in distinguishing it. (Interestingly, it is sometimes easier to learn to produce the correct sound than to recognize the correct sound.)

The difference between the English d /d/ and the voiced English th /ð/ is another of these cases where a sound (/ð/) just doesn't exist in many other languages, and the closest approximation (/d/) is what the brain fills in. Over time, it is possible to adjust and learn to hear these sounds, but it takes time and a lot of exposure and practice. Until then, context helps.

  • Actually, native speakers wouldn't normally hear the difference in many sentences! :) Have tried to explain why below! (long or short answer available). Like your post! – Araucaria Oct 26 '15 at 4:00

Full answer and experiments you can try at home

[For short answer see above/below]

An important part of your mouth:

If you feel behind your top teeth with your tongue, you should be able to feel a little shelf-like part right there behind your top teeth. Now if you run your tongue backwards behind that, you'll feel that your mouth suddenly arches upwards to form the so-called roof of your mouth.

That little shelf-like bit behind your teeth is your alveolar ridge. Now, if you're a native English speaker, then if you make a /t/ sound ('tuh', 'tuh', tuh'), you should be able to feel the top of the tip of your tongue making contact with your alveolar ridge to articulate the sound. If you try it with /d/, /n/ or /l/ you should find the same thing.

Place of ariticulation

Now try saying this phrase a few times:

  • hid us

You should still be able to feel your tongue making contact with the alveolar ridge for the /d/ there, hopefully. The sound of the /d/ might be a little different for you if you speak an American variety of English.

Now, if you've done that a few times try this sequence:

  • hid them

What you'll find when you say this (probably) is that you aren't making your /d/ on your alveolar ridge any more. Instead, you'll be making it on your teeth, in the same place that you make the 'th' sound, [ð]. The /d/ has moved. It has become dental (made on the teeth).

Now - if you don't replace your /t/ with a glottal stop at the end of a word - you should find that the same thing happens with the following sequences too:

  • hit us (/t/ on the alveolar ridge)
  • hit them (/t/on the teeth, dental)

All the sounds that we make on the alveolar ridge in English are highly unstable. One reason for this is that it is difficult to move quickly enough from an alveolar contact to another contact nearby. There are many other reasons too, which we won't go into here. You can try this kind of thing with other alveolar sounds such as /l/ or /n/:

  • all of them (alvoelar l)
  • all the time (dental l)
  • ban us (alveolar n)
  • ban them (dental n]

So what we been experimenting with is the fact that /t/ and /d/, when we articulate them, tend to move position quite a lot. In fact they will sometimes move so far, that we will recognise them as a completely different consonant. So try saying the following as spelled:

  • Its a very goob book.

This phrase should be straightforwardly recognisable to you as "It's a very good book". This kind of transformation (called assimilation) is not obligatory, but it happens all the time, even in slow careful speech.

Dropping sounds altogether: elision

So we've worked out that /t/ and /d/ are unstable in that they move around a lot. But they also get freely omitted, or elided in certain environments too. Consider the following phrases:

  • Mind the gap.
  • Mind Amy.

You should find the following pronunciations of these two phrases very different in terms of their acceptability :

  • Mine the gap. /maɪn ðə gæp/
  • Mine Amy. /maɪn eɪmi/

The first will probably sound ok to you. The second will be considered unacceptable by most speakers. Now some speakers will balk at the idea that they ever elide a /d/ in phrases like mind the gap and find it hard to believe that it is a quite natural part of the language. If you find yourself among this number, then there's a little experiment that you can do. Find a native speaker (right now, if you can) and ask them what you're saying. Use the phrases above mine the gap and mine Amy, or mine a child. For the last two, you'll find that they don't understand what your saying. But for the first one they'll come back to you immediately with mind the gap. A nice second experiment is to tell them you didn't say a /d/ there - and then listen to them tell you that you most definitely did!

That little experiment we've just done shows us that we cannot freely omit /d/ before a vowel. The same thing goes for /t/ too. Try we buss them wide open and a buss of Mozart for we bust them wide open and a bust of Mozart. The first should be acceptable, the second definitely isn't.

Now we will quickly find that we can't drop freely drop /d/ or /t/ when preceded by a vowel either. We need consonants on both sides. Consider

  • bind them: "bine them" /baɪn ðəm/
  • abide them: *"abie them" /əbaɪ ðəm/

The first should work for you, but the second definitely is not an acceptable substitute.

There's one last experiment we need to do. Try out the following pronunciations and decide if any are acceptable substitutes for you (or someone sitting nearby):

  • cole weather for cold weather
  • hol the advance for halt the advance
  • loss the plot for lost the plot

The first and third examples should be fine. The second is unacceptable. There is a simple reason for this, but it's difficult to just guess it. Some consonants that we make involve vibration of the vocal folds. They are "voiced". An example would be /m/. You can sing tunes with these kinds of sound. Other sounds just involve the expulsion of air from the mouth. An example would be the 'sh' sound we hear in sshh , don't wake the baby. If you try to hum a tune using sh, you'll find it has no pitch, so you can't get any real musical note going (try it!).

Now, /d/ is voiced and /t/ isn't. A /t/ just involves the movement of air. If we want to drop a /t/ or a /d/, then the previous consonant must match for voicing. In cold weather the /l/ like the /d/ is voiced. In lost the plot, the /s/, like the /t/, is unvoiced. So in these two cases we can felicitously lose the /t/ or /d/. However, in halt the advance the /l/ is voiced and the /t/ is not. For this reason we cannot drop the /t/ here.

So, in order to be able to freely drop a /t/ or /d/ the following conditions need to be met:

  • It must be at the end of a syllable
  • It must be surrounded by consonants
  • The preceding consonant must match it in terms of voicing.

One last thing, the conditions above will not be met if one of the surrounding consonants is /r/ or /h/. Boil ham does not work as a pronunciation of boiled ham, neither does boil rice for boiled rice.

Past simple endings

For regular verbs, the past tense suffix appended to verbs in English is represented in the orthography by -ed. In the actual speech the situation is slightly more complicated. When the base of the word ends in a voiced sound (or lenis consonant), we usually add a /d/, which is voiced. If the base ends in an unvoiced sound we usually add a /t/, which is unvoiced. But if the base itself already ends in a /t/ or /d/ we add a vowel before the ending so that the past tense morpheme is distinguishable. Because there is now a vowel before the suffix, and vowels in English are voiced, the final consonant in such situations is a /d/. We therefore see the following types of endings:

  • claim: kleɪm --> kleɪmd (voiced consonant, /m/, voiced d)
  • drape: dreɪp --> dreɪpt (unvoiced consonant, /p/, unvoiced t)
  • rate: reɪt --> reɪtɪd (t + ɪd)
  • fade: feɪd --> feɪdɪd (d + ɪd)

The Original Question

When the base form of a regular verb ends in a vowel then we will normally be able to tell that the verb is past tense from (approach phase of) the /t/ or /d/ suffix.

When regular past tense form of a verb is followed by a vowel, we will likewise be able to audibly distinguish the form by it's suffix, which will be clearly audible because of its release.

However, when the base form of a regular past tense verb ends in a consonant and is also followed by a consonant (not including /h/ or /r/ in either case) then things may be significantly more complicated. I say may be because it might simply be the case that the /t/ or /d/ is pronounced in a canonical fashion and is clearly distinguishable from the consonants surrounding it. For example in the following sequence, if the /d/ is clearly pronounced it will be clearly audible:

  • ... bowled when ...

The /d/ here may be clearly articulated and, if it is, will be easily discernible.

However, there are two other possibilities. The first is that the /t/ or /d/ may be subject to assimilation, or similar processes. So for example, in the string:

  • billed them

... the /d/ might change its place of articulation to the back of the teeth to match the following /ð/ ('th' sound) at the beginning of them. This is what we saw with hid them further above. In this situation it may be much more difficult, if it is actually possible at all, to audibly discern the /d/ or /t/ suffix.

Also, in theory, we should be able to drop the /t/ or /d/ ending altogether for regular verbs in these circumstances. If the end of the base of the verb and the beginning of the following word are both consonants, then the /t/ or /d/ ending is surrounded by consonants. Now, for regular verbs, the /t/ or /d/ always matches the preceding consonant, because as we saw above we choose /t/ or /d/ precisely on this basis. There is never a mismatch. In practice, there do seem to be some exceptions to our being able to drop the /d/ or /t/ ending - but in general the rule holds good. Now, if the /d/ or /t/ has been dropped altogether, then obviously we cannot distinguish between a past tense and present tense verb by the sound. What we hear isn't the crucial factor here.

So these two factors, namely that the place of articulation may change to match the following consonant and secondly that the past tense suffix may be elided, mean that we have to depend on the context to tell us whether we have just heard a present or past tense verb. And it follows that - if the context is not clear enough - we may not know!

Consider the following examples:

  • I push them out the window.
  • I pushed them out the window.

These two sentences will be indistinguishable for most speakers by sound alone. Here's another experiment for you. Find a subject, ask them what you're saying and then say:

  • Yesterday, I push them out the window.

You're guaranteed to be heard saying pushed them out the window. When you think about this carefully, it is not so surprising. The tense of many irregular verbs is similarly indistinguishable by sound alone. Consider:

  • I put them on the floor.

This might mean that you do it every day or that you did it yesterday. If you stick a usually or a last week onto the sentence, the tense will become clear. But we don't find cost, let or put for example to be particularly problematic even thought their past and present tense forms are the same.

As is very often the case in language, we often know what one sound or word is, not because of the form of that actual sound or word, but because of what's surrounding it.

  • 1
    tl;dr I have some disagreements with the parts I read (and likely more with the parts I didn't) but you have the basic idea there. I will say that with "Its a very goob book" I can tell the difference (if not too rushed/jumbled), but I would still interpret such pronunciation as having said "good" (though imperfectly). – Hot Licks Oct 26 '15 at 1:38
  • @HotLicks, what does "tl;dr" mean? I've seen this in various places on the web, but never seen what it's supposed to signify. – Cyberherbalist Oct 26 '15 at 17:09
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    @Cyberherbalist - Too long; didn't read. – Hot Licks Oct 26 '15 at 19:37
  • Your comprehensive explanation was a pleasure to read. You made a point about how sometimes we leave out some sounds while the listener hears them in their brain. Nevertheless, some other aspects are neglected, I'm afraid. For example one's ethnicity, social class, accent, and even the situation affects one's manner of speaking. Delivering a formal speech, talking with your friend or singing a rap song, each alters the way you articulate the same words. Another neglected aspect is rhythmical differences (as mentioned in a comment below your short answer). – Færd Oct 26 '15 at 21:09
  • Occasionally, I write/revise subtitles for films. Sometimes I have to listen to the same sentence a dozen times, to finally decide (or give up on) what exactly is being said. In many cases I get surprised by how infinitesimal the nuances are, and how they subconsciously get recognized or ignored. Since we need real-life examples to base our statements on, I'm going to provide a few samples (links from YouTube and other sites), in favor of both your argument and mine. Tomorrow, maybe. It's the middle of the night here. – Færd Oct 26 '15 at 21:18

I think the answer is that they sound different.

And I think the difference is this: When killed is pronounced in this context, your mouth is positioned as if it were going to pronounce the d, but it is not, or is hardly, pronounced. Because your mouth pronounces the coming from the position for pronouncing the d, the resulting sound is different from what happens for kill the.

The same kind of thing happens, I think, for distinguishing can't from can. Your mouth is positioned to pronounce the sound for the letter t when the following word is pronounced. This is different enough from moving from can to that following word -- the difference can be heard, at least by native speakers.

Someone knowledgeable can speak to whether any of what I'm guessing is true. ;-)

  • Hmm, Iots of things about your theory are very attractive ... :) [not sure if they're right yet though!] – Araucaria Oct 20 '15 at 0:38
  • Just a personal observation and interpretation. Maybe someone will explain what is really going on. ;-) – Drew Oct 20 '15 at 0:40
  • Well, I've done my best in a post below! (there's a long and a short one! In regard to your observant comment about the place of articulation; both the /d/ and the /l/ in killed the and kill the will move to the following 'th' position :) – Araucaria Oct 26 '15 at 4:09

When you say kill them you put two voiced sounds together: /kɪəm/ whereas when you say killed them your breath channel becomes blocked between these two sounds for a tiny fraction of a second: /kɪl.ðəm/. The /d/ sound is not fully pronounced, but the blockage is still there (denoted by a dot).

Although /ð/ and /d/ are pronounced from about the same place in your mouth, surely the latter causes a stronger friction or even a blockage in the air passage. Carefully observe the air pressure in your mouth and throat and notice any fluctuation thereof when you say kill them and when you say killed them. Isn't the pressure slightly higher in the second one, between the sounds /l/ and /ð/? This pressure difference may cause a slight change in the rhythmical pattern of the sounds and may result in a more intensified /ð/. This is what a skilled ear catches and therefor tells one set of words from the other.

The bottom line of my answer is that there is not 100% resemblance between kill the and killed the (and between some other resembling sets of words), and sometimes it is possible to hear those differences without the help of a context.

  • Your answer is spot on for when we actually pronounce the /d/ . – Araucaria Oct 26 '15 at 10:40
  • @Araucaria The /d/ sound is not fully pronounced, but the blockage could still be there. (first paragraph) – Færd Oct 27 '15 at 11:03
  • /ð/ and /d/ are not "vowel sounds", nor are they "pronounced from about the same place in your mouth". They are both consonants; /ð/ is an interdental and /d/ is an alveolar. – fdb Oct 27 '15 at 13:44
  • @fdb I think the vowels was probably a typo on Farid's part. However, when you actually say killed them you'll find that both the /l/ and the /d/ (if you articulate the /d/) which are normally alveolar, will move to the same place of articulation as the following sound. So, yes, canonical versions of /l/ and /d/ are alveolar, but in this sequence they'll become dental under the influence of the following /ð/. Try it and see! There's a bit about that in my answer :) – Araucaria Oct 27 '15 at 14:27

There may be a slight pronunciation difference for some speakers between

they first kill the trees,


they first killed the trees.

(Although note that the consonant starting the is /ð/ and not /d/.) However, I think that in most dialects this pronunciation difference is either non-existent or too small to hear consistently. I believe that most native English speakers distinguish them in the same way they distinguish between

they first cut the trees down (present),


they first cut the trees down (past).

Namely, they use context.


In English there are three ways to pronounce the past tense suffix "ed": "d" as in killed; "id" as in hated; "t" as in jumped. I think the OP meant to use a verb whose past tense ends in a "t" sound to make the point that the present and past tense if not fully enunciated sound similar when the verb is followed by "the."

Example: They jump the wall. They jumped the wall.

I defer to the Sages of the Stack as to why they sound similar.

  • Are you sure if you here it, you won't be able to tell if it's jumped the or jump the? Or if it's killed duh or kill duh? Unless the speaker speaks too fast, the first ones will have more intensified t s or d s or whatever. They're not that undistinguishable. – Færd Oct 21 '15 at 8:24
  • @ Farid You're right and I tried to qualify that. – Zan700 Oct 21 '15 at 8:59
  • @Farid Actually, that's not what's going to happen. See below for why. You're right that it's counter-intuitive, but it is :) – Araucaria Oct 26 '15 at 4:03

Short answer

When surrounded by consonants, the past tense suffix of regular verbs is often inaudible. This can be because it is masked by other sounds. Alternatively, it may be because we change the part of the mouth that we make the consonant with to match the sound that follows. Lastly, when surrounded by consonants (not including /h/ or /r/), the /t/ or /d/ ending may be dropped altogether. This is because it will always match the preceding consonant in terms of being voiced or unvoiced (a prerequisite of its being a regular verb) and this fulfills the requirements for being able to drop (elide) the ending altogether.

Therefore, in the same way that we do for irregular verbs whose past and present tenses are homophones (sound the same), we depend on context to tell us whether the speaker intended a past or present form to be understood. Out of context it may not be possible at all. Consider, for instance:

  • I let her use my car.

This sentence may mean she can use it all the time, or it might be talking about a past event - we do not know. The same thing applies with regular verbs in many circumstances, for example the following sentences may be audibly indistinguishable:

  • I walk down to the pier
  • I walked down to the pier

Nonetheless, in real life this does not cause any real problems to native speakers or listeners. A listener will nearly always have been provided enough context to infer the difference.

  • "I walked down to the pier" has a long [k]. This makes a rhythmic difference between the last two sentences. Say them aloud -- you'll hear it. – Greg Lee Oct 26 '15 at 4:59
  • @greglee In SSBE it doesn't seem to work that way. Native speakers can reliably distinguish between "guest" and "guests" where there is a genuine double length 's' after the elision of /t/ whereas they can't between "guess tails" and "guessed tails". Same goes for the /s/ in "asked them" where both /k/ and /t/ may be elided. – Araucaria Oct 26 '15 at 8:53
  • @GregLee Although a double length /k/ is exactly what you'd perceive if you used a glottal stop as an allophone for the /t/, as opposed to eliding it. – Araucaria Oct 26 '15 at 10:52
  • No, it isn't. I perceive a double [k] because that's what I say. Are you proposing that [t] becomes glottal stop which then assimilates to the preceding [k]? Why? It wouldn't explain the lengthening of the [l] in "kill the". (Why do you keep using slashes for phonetic forms?) – Greg Lee Oct 26 '15 at 17:00
  • I couldn't figure out how to interpret your last comment. What does "that way" mean? Geminate consonants are distinguished by rhythm. – Greg Lee Oct 26 '15 at 17:04

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