/t/ and /d/ share manner and place of articulation and differ in voicing (/t/ is voiceless and /d/ is voiced). So, in theory they are exactly the same sound except for the fact that when we produce a /d/ our vocal folds vibrate and when it is a /t/ they don’t. Unfortunately, things are a bit more complicated than that. In order to pronounce /t/ and /d/ well, we have to take into account more elements, and this is even more important when we compare them to Spanish /t/ and /d/.
As was explained in the article about /p/-/b/, the three plosive pairs behave in the same way, so almost everything said here can be applied to the pairs /p/-/b/ and /k/-/g/ as well. However, in the case of the English /t/ and /d/ there is an additional difference with their Spanish counterparts: the place where the sound is generated is different. In Spanish /t/ and /d/ are produced by touching the back of the upper teeth with the tongue (they are dental), whereas in English the tongue is placed a bit higher, against the alveolar ridge (they are alveolar). So, in order to produce English /t/ and /d/ correctly, you have to raise your tongue so that it doesn’t touch your teeth but the hard area above them. Do this and you’ll see how the quality of your English /t/ and /d/ changes immediately.
Now let’s listen to some minimal pairs:
You will probably have noticed that, even though /t/ and /d/ are different, they are produced in a very similar way.
Spelling: t (tired), tt (attend), te (write), ed (in past verbs after a voiceless sound: asked), th (thyme)
Let’s now compare the following words:
Listen to them in context:
No doubt there is a big difference between the English and the Spanish /t/. Part of it is due to the fact that the tongue is placed a bit higher, but there is more to it than that. I’m sure you’ve heard the puff of air -like a small explosion- which is expelled when an English /t/ is produced. This is called aspiration and it is an essential characteristic of English voiceless plosives (/p/, /t/ and /k/) when they appear at the beginning of a stressed syllable. It is a feature that doesn’t exist in Spanish, so we have to get used to doing it in the English way. As we’ll see in a moment, learning how to pronounce /p/, /t/ and /k/ correctly -that is, accompanied by that puff of air- is crucial to avoiding misunderstandings.
Here are some examples plosive consonants said by native speakers. Look at how the letters in red are pronounced.
In the examples above, the aspiration of voiceless plosives can be clearly seen in words such as problem, talking, time, talent, tussle, playwright, playable, came, case, etc. On the other hand, there is one example of each voiced plosive –day, Birmingham, Grand- where the absence of aspiration is also evident.
Spelling: d (day), dd (odd), ed (in past verbs after a voiced sound: rained)
Let’s now compare the English and Spanish /d/ sounds.
Listen to them in context:
You’ve probably noticed that the English and Spanish /d/ are not the same. Apart from the higher position of the tongue, there is something else. As we said with the /b/, the English /d/ sounds dry and flat while the Spanish /b/ sounds somewhat richer. This is because the three voiced plosives (/b/, /d/, /g/) are devoiced when they come at the beginning of a word, that is, they are produced with no vocal fold vibration.
Let’s listen to some clips where the /d/ is pronounced by native speakers.
The devoicing of voiced plosives has a very important consequence. When /t/ and /d/ are at the beginning of words, English speakers don’t distinguish them by their voicing, since /t/ is voiceless and /d/ is devoiced (so, there is no vocal fold activity in either of them, they’re both voiceless de facto). They distinguish them because of the presence or absence of aspiration -the puff of air mentioned before-, because /t/ is aspirated and /d/ isn’t (remember the minimal pair tear-dear). So if you pronounce the sound /t/ in the Spanish way -that is, without aspiration-, an English speaker is most likely to understand a /d/ (as I said, this happens with the pairs /p/-/b/ and /k/-/g/ too).
d between sounds. Finally we’ll address an issue which is responsible for the strong foreign accent of many Spanish speakers of English: the pronunciation of voiced plosives (/b/, /d/ and /g/) within words. Let’s listen to the following examples:
It is clear that the English /d/ is very different form the Spanish /d/ when it is found inside a word. Here the problem is that, in medial position, the Spanish /d/ is no longer a plosive but a fricative. This means that we don’t stop the flow of air before producing the sound. Instead, we go smoothly from one to the other. Check this by means of an experiment: say the Spanish word adicional and you’ll see that, when you are producing the /d/, your tongue doesn’t touch the alveolar ridge, so the typical closure of plosives cannot occur. Now, If you want to do it well, make sure that your tongue reaches the hard area above your teeth, and the sound will come out perfectly. Do it in this way and you’ll get rid of the problem once and for all.
And here is an example of the English /d/ in medial position.
Do it in this way and you’ll get rid of the problem once and for all.
But, unfortunately, the trouble doesn’t stop here. There is another little detail to mention. We don’t normally speak in isolated words, but in chunks of speech where words are linked to one another. We produce an uninterrupted stretch of sound. For this reason, we are likely to pronounce the /d/ badly even when it comes at the beginning of a word. Have look at this example:
Keep this point also in mind and you’ll improve your pronunciation immensely.