Thank you very much.  I appreciate your help. 

I have a theory.  If two words come together and the second one starts with the same vowel that the first one ends with, the words which has a stressed vowel is the one which keeps the vowel sound.  For example

mucha agua (the first "a" in agua is stressed) is pronced much-agua

está aquí (the “a” in está  is stressed) is pronounced  está-quí

I have no theory as to what would happen if both the last vowel in the first word and the first vowel in the second word are stressed, or if neither vowel is stressed.

Using this rule da asco ("a" in asco is stressed) would be d-asco.  But the “d” can not stand on its own as a syllable.

What do you think?

I realize that the only real answer is to lesson to as much Spanish as possible, and not to analysis it so much.I

What I see as what we call a 'stressed syllable' is really two things: a shift to a higher, falling pitch, and a slightly longer duration of pronunciation.  So in "agua", the first 'a' has a higher pitch, falls in pitch during its pronunciation, and is pronounced slightly longer.

Second, that the 'stressed syllable' is dominant.  The qualities that I've mentioned above make it so.

So when looking at está aquí, if said fairly slow (in terms of a native speaker), you could hear the longer, higher pitched 'a' followed by a drop in pitch, then the 'q'.  AAAAAaaah.  Nevertheless, our hearing is tuned to pick up or notice the higher pitched, falling tone and may ignore the flat, lower pitched tone of the second 'a' that's barely pronounced, as it blends in easily with the end of the falling pitch tone of the stressed 'a'.  Now if you speed things up, then the drop from the high pitch to the low pitch shortens, and it's the lower pitch that loses out.  What I mean is that the a sound will start at the same pitch, but if spoken quickly, it will not drop in pitch to as far as it would if you really enunciated "está aquí".  So because of this, you could say the second 'a' virtually gets "swallowed" into an already existing component of the first 'a'.

JPvillanueva may understand some of what I'm saying due to learning Chinese.  In Chinese each syllable has a tonal value, and one of the tonal values is high pitch to low pitch (tone 4), such as the example of está aquí. However when Chinese speakers speak faster, or just speak normally, they don't pronounce their tones in the same full range; they shorten it.  It's somewhat similar to this but still a whole other can of worms!

Now, if you're still reading, haha, I believe the same, yet reverse, happens with mucha agua.  The flat, lower pitched 'a' found at the end of mucha is still there, when pronounced slowly, with a sudden sharp rise in pitch as the speaker starts to say the word agua.  However, when speaking quickly, the speaker will start saying 'agua' right after the 'ch' in mucha, therefore obliterating the non-dominant first 'a'.  What's really happening is that right after the ch, the higher pitched 'a' sound is pronounced without initially pronouncing the low-pitch of the first 'a'.

As for both a's not being stressed, like hasta ahora, then both a's are flat and low-pitched, not emphasised, so sound just like there were only one 'a'.

As for two stressed a's side by side, this is a case of two falling tones side by side.  I can't think of an example so let's use a fictitious example of 'está agua' (although I believe "da asco" is also an example, but I digress).  So if pronounced slowly, you'll start the high pitched 'a' sound at the end of está, and let that 'a' fall in pitch.  Then as the speaker starts the second 'a' (the first 'a' in agua), the pitch then sharply increased back to a high pitch, and then falls again.  As the speaker increased their speed of speech, these two falling tones merge, and what happens is that the first falling tone just doesn't fall as far.  The length of falling, I believe, shortens to the point where they completely merge.

Perhaps I should mention that pronunciation and analysis thereof are one of my favourite parts of learning languages?  :)  I think it's one of, if not the biggest, main motivating reasons that in the past I've started learning 5 languages.  And also no mystery why I never continued with most of them!

smithtopher

Wow I am imprested.  I have to admit that I am quite ignorant on the subject.  I thought that if a vowel was stressed, it just meant that you say it a little louder.  Thank you for so much info I will take a little time of absorb it all.

Jp I saw in smithtopher’s profile that he is an engineer.  I am an engineer as well.  I know we are supposed to learn through use and not try to analyses things too much, please understand that it is our nature.

I understand the reason not to overanalyse, as I've struggled with preoccupying myself with analysis to the point where it chokes me up, makes me speechless as I fear any mistake I might make.  To remediate this I've tried to let go of my fear for mistakes.  However analysis like this is one of my great joys, so I can't won't remove it from my learning process!  :P

So you're an engineer too, steverstrv, now it totally makes sense why you took this interest in pronunciation!

pero me encanta el olor de gasolinera. De hecho me gustan los olores de pinturas plasticos solventes y muchas cosas petroquimicas

Esta lección estaba bien por mí. Mi español es malo. Pero en la compañía que yo trabajo, yo he oído la palabra ‘cochino’ mas, hasta ahorita yo nunca he oído de la palabra ‘wácala’. Cuando yo pregunto de la palabra mi amiga dije que es ‘guacala’. ¿Es esto un diferente camino la para deletrear? 

Gracias

-Rebecca

I've heard from spanish speakers that when a word starts with a "ua" or "ue" or any other dipthong (two vowels side by side) that starts with a "u", that a "g" is often inserted.

Why?  Supposedly it's easier to say with a "g"!!

Example: "me huele" is often said like "me guele"

thesmithtoper, sorry but yes we tend to pronounce like if there is a G, je.