confusion over the pronunciation of two devanagari letters.
During my lessons it gave me an audio cue for a "sh" sound. 2 of the options i had to choose from was श and ष. as i moused over them both i got the same audio sample so i had a 50/50 chance of getting it wrong. Is it really the same audio sample? does anyone have any advice on how to avoid this?
श and ष do represent two different sounds: श is a palato-alveolar fricative while ष is a retroflex fricative. Basically, श is "English sh" (as in "shape") and ष is "Russian sh" (ш). However, people often, if not always, pronounce both of them as श. This might have to do with the absence of word pairs in Hindi that differ only with respect to श/ष and the fact that श is the easier one to pronounce.
Since the audio samples in this course aren't helpful in discerning them, you can make use of the fact that ष occurs in way fewer words than श and try to memorize the words containing ष as you come across them (there won't be many of them). It's just a matter of getting used to and you'll have it down in no time.
As far as I understand, there are three "s"-like sounds represented by the symbols "स", "श" and "ष" (BTW, they are represented by a single button on the iOS Hindi keyboard). The first one (स) gives the regular "s" sound like in "Sun"; The second one (श) gives the "sh" sound also known in English, like in "SHame"; The sound for last one (ष) doesn't exist in English, though. One pronounces it like "sh", but with the tongue curled backwards, so that its tip touches the roof of the mouth, but further than for the "sh" sound. मैं हिंदी नहीं बोलता हूँ, so this may not be a 100% accurate description, but this is how people teach this sound online, including YouTube, so one can listen to the three of them to feel the difference. I have to admit, the Duonlingo audio for these two sounds is confusing for me as well.