Differentiating between 'si' and 'sí' in spoken Spanish
How to you tell the difference between si and sí in conversation? Is this all based on context, or are there certain ways that a statement with "if" is phrased to give other clues to the listener?
6 Answers
If it's "yes", it's set apart slightly. On the other hand, if it's "if", it flows immediately into the next word. Examples: "Sí, vamos" vs "Si vamos". For "yes, we're going" you would emphasize the "Sí" part slightly (unless you really want to hit it) and after a slight pause you would continue to the "vamos". However, "If we go" would be one big 3 syllable sounding word, such as "sivamos".
I hope this has helped. It takes practice, but once you start listening for it, you will be able to distinguish fairly quickly.
Let's clear this up:
sí: it is written with an accent, and it is pronounced using higher harmonics (in terms of frequencies), and generally with higher intensity, i.e. with stress. It means "yes".
si: it is written without an accent, and it is pronounced using lower harmonics (in terms of frequencies), and much lower intensity than any typical word with a stress. It means "if".
To a native they sound as different as day and night (if pronounced correctly). Context has nothing to do with it. If you record a native and you show me a spectrogram, I can tell you which one is which.
Just to give you an example: can you tell apart the two "refund"s from these sentences if you heard them in isolation? "I want to give you a refund". "I will refund your expenses." That's how different "si" and "sí" sound.
P.D. Although "sí" in isolation is likely to last longer than "si", without pauses their lengths are statistically identical. It is the pitch and the intensity what differentiate them.
"Sí" when in oppistion to "No", is always accentuated.
"Si" when it is conditional ("Si fuese más alto....[If I was taller]", "Si hay vida en Marte....[If there is life on Mars]", etc.) does not have an accent.
"Sí", used as a pronoun, always calls for an accent. (e.g. "lo hizo por sí mismo"[he made it by himself]).
"Si" as a musical note, doesn't call for an accent either.
(I found this in a Spanish-speaking forum as I was also confused)
well... when affirmating /í/ is sharp, short and high... when conditining /i/ comes longer and deep... well just sometimes... it depends the own style... sometimes just there's no difference...
..y si(iii) vamos al concierto... anda di que sí(iii) (can be the same that the begginin)... ¿sí, sí, sí? (can be sharp and short)
I think you have to use context to tell the difference. Which one makes sense? I can't think of a single instance in which yes and if would both make sense in the same place. So it's really not all that hard. 
I agree with Valerie. The context will almost always clear things up.
Ex: Sí, puedes cantar si quieres. (Yes, you can sing if you want)
