I never said it wasn't three syllables. I said there's no break or glottal stop in between, so that the net effect is essentially that you are holding the consonant for a double length (as noted earlier, with a slight difference in tone). I am trying to encourage beginners NOT to insert random glottal stops or pauses into their words simple because there are two of the same letter in a row.

Miland:The stress in Esperanto is on the next to last syllable, so there is a distinction between the last two syllables, which IMO could vary from a shift in tone or volume to a glottal stop, depending on whatever speakers find convenient. A light glottal stop might be easier for some than a continuous vowel.

I think the shift in tone is more what we're looking for.

It's interesting that when we talk about accented syllables in Esperanto (as with English), we're usually talking about the syllable being louder. But I think if we really listen, most people have a change in tone on the accented syllable as well, often several notes higher on a musical scale. For some reason that's rarely discussed. (That would make an interesting linguistic study for Esperanto.) Even languages that aren't tonal in the sense that Chinese and Thai are... tone plays a big part in how they're spoken.

In Japanese, these double vowels are common. The vowels are considered two separate syllables, but aren't separated by any sort of glottal stop. Often the shift in tone lets you know it's a double vowel. I believe that the given name Hirō (or Hiroo, depending on how it's transliterated) features a significant drop in tone (and probably volume) on the second O syllable.

Kirilo81:In my opinion the following three examples do it right: Forvo: herooj. There is a difference between the two os, at least in tone.

Which one of the three examples are right? To me, they all sound different.

Vortarulo: sounds like three beats.

Tibisko: sounds like two beats, then one beat.

Archos: sounds like two beats.

Then there is the forvo entry for "heroo"

Mutusen: sounds like two beats.