La sinalefa — The vowel bridge
«¿Qué vas‿a‿hacer?»
When one word ends in a vowel and the next begins with one, Spanish fuses them into a single syllable. «Vamos a ir» comes out as one breath. In fast speech the vowel join is roughly half as long (about 380 ms down to 125 ms), with no catch in the throat. Leave the gap and you sound like you are reading a list.