"rs" pronunciation rule
So I know that when an s follows an r the pronunciation becomes kind of like the "sh" sound in English. Based on comments here it seems like this applies even across two words (e.g. Hon säler sin hund).
However at times I find audio online elsewhere in which the s does not turn into a sh. I also talked to a couple of native speakers and got conflicting answers.
So which is it? Can both be considered correct?
Also, just out of curiosity why does rs-->sh? Is it simply a rule of the language, or does it naturally happen when native speakers try to pronounce an r followed by an s?
In most of Sweden, rs is pronounced as English 'sh'. That is a rule. The same goes for the combinations rn, rt, rd and rl. They are all pronounced at the same position as 'sh' in the mouth. All of these occur across word boundaries as well, with the r "jumping over" to the next word: Hur så? 'how come?' is pronounced 'hu SHå'
This does not happen in the areas of Sweden where the r is pronounced in the back of the mouth, however.
Well, I guess it's a decent approximation in the case of 'rs', but if you are going to learn the other sounds you might as well learn 'rs' correctly as well. The key is that they are retroflex consonants, which means they are articulated with the tongue curled backwards against the front part of the palate. So try saying english 'sh' with your tongue curled backward, and the same for n, t, d and l. 'rl' is a special case though, and many people pronounce is as a plain 'l'. I'm sure there is a video tutorial somewhere on YouTube on the pronunciation.
They are commonly called retroflex consonants, but for most speakers they're actually post-alveolar, and would be more accurately described as such. Swedish 'rs' is thus pronounced with the tongue in the same position as English 'sh'.
By that I'm not saying that they can't be retroflex, because they can, but the retroflexion, when it appears, tends to be weak in Swedish. But again, in most dialects they are simply post-alveolar.
Yes, if a /t d n s l/ comes next to a postalveolar consonant, it will assimilate. Thus hjärtslag is pronounced hjäTSlag (using capital letters to denote postalveolars here). If you pronounce "värdshus" as it is spelled, then it is as you say, väDShus. The more traditional pronunciation has assimilated further, väShus (as if it were spelled 'värshus') :)