As mentioned in the Tricky Combos section, combining other alveolar consonants with the alveolar tap can be difficult, since doing so requires two successive tongue movements. The combos discussed here all involve alveolar consonants. In contrast to the Tricky Combos, however, the difficult combos are very common and ALWAYS articulated completely. So you have to master them completely.
There are essentially two combos of concern here, the d-& combo and the t-& combo (/d/ and /t/ are the same physical movement, they only differ in that /d/ is voiced and /t/ is unvoiced). If you recall from the consonants section in The Sound Primer, the Spanish d̪ and t sounds differ from the English /d/ and /t/ in the point of the tongue used. For Spanish d̪ and t, you use the “blade” of the tongue, and for English /d/ and /t/ you use the tip of the tongue.
The only way to consistently hit the Spanish d̪ -& and t-& combination at normal Spanish speeds is if you do the Spanish /d̪/ and /t/ sounds (blade of the tongue). If you do the English sound (tip of the tongue), you will struggle GREATLY.
If you think about it, it will make sense to you. The alveolar tap /&/ is made at the alveolar ridge at the tip of the tongue; so is the English /d/. So to combine the two sounds, you would have to move your tongue quickly in two distinct movements.
If you do the Spanish // however, you can pull your tongue back to release the /d̪/ sound THEN, in the same motion, touch the tip of your tongue to the alveolar ridge to create the “alveolar tap.”
If you can successfuly visualize this, you will see that with the Spanish /d/, you can make this combo in one movement. With an English /d/, you need two distinct movements. In language, it’s all about finding the easiest route. Build the easy-route habit now and focus on making ALL of your Spanish “d” s with the blade of your tongue instead of the tip.