I can only hear the difference between these 2 words when I hear the word 비싸다, but apart from that, are there any other ways to tell 사 and 싸 apart? And is doing that even necessary?
2 Answers
I tried summarizing the paper "Korean fricatives: production, perception, and laryngeal typology" (Charles B. Chang, 2007), which examines the acoustic differences between ㅅ and ㅆ. h/t @sumelic's answer on a different question.
Basically, ㅅ has longer aspiration (think [s] followed by [h] or [x], not to be confused with [∫]) but is shorter overall. On the other hand, ㅆ has shorter aspiration (so, kind of like English "s" sound), but is longer overall.
(Though, the author also says "Note that these data contradict the results of Cho et al. (2002) ["Acoustic and aerodynamic correlates of Korean stops and fricatives"], who claimed that the non-fortis fricative including aspiration [ㅅ] was longer than the fortis fricative [ㅆ]". If you look at that paper, Figure 15 shows that, excluding aspiration, ㅅ is shorter than ㅆ, but including aspiration, ㅅ is longer than ㅆ.).*
The author also finds that there are effects on the following vowel (he only tests 사, 싸, 수, and 쑤); for 사 vs. 싸, 사 has higher F1 onset, slower amplitude buildup, and steeper spectral tilt. But 수 vs 쑤 had no difference in the vowel. I'm pretty sure these effects are basically a consequence of pronouncing ㅅ like [sx], but I'm not sure.
Here's an excerpt from the Conclusion section of the paper:
In summary, this study examined the production and perception of the two-way laryngeal contrast in Korean sibilant fricatives in four experiments covering a low (/a/) and a high (/u/) vowel environment. Acoustic analyses show that in a low vowel environment, the two fricatives differ from each other in segmental duration, aspiration duration, F1 onset, intensity buildup, and voice quality; however, the F1 and intensity differences disappear in a high vowel environment. In both environments, there are no differences in f0 onset, average intensity, or vowel length.
The results of the perception experiments demonstrate that the coalition of F1 onset, intensity buildup, and voice quality is important in the perception of this contrast. These vocalic cues appear to outrank the consonantal cues of segmental duration and aspiration duration, with F1 onset and intensity buildup being the most salient.
*Cho et al (2002)'s word list for Seoul ㅅ vs ㅆ is 사다, 싸다, 나사다, and 바싹.
Oh yes, ㅅ and ㅆ make two distinct sounds and mixing them would create confusion. For example, 이거 사 주세요 means "Pleas buy me this" whereas 이거 싸 주세요 is "Please wrap this for me" (사다 = to buy, 싸다 = 1) to wrap (v), 2) is cheap (adj)).
There is no simple way to tell the two sounds apart other than training your ear on the subtle differences. The difference is part of the general pattern of plain unvoiced sound vs tensed sound in Korean, as in ㄱ vs ㄲ, ㄷ vs ㄸ and ㅈ vs ㅉ, in addition to ㅅ vs ㅆ.
In simple terms, it can be thought of as s soft sound (ㅅ) vs fuller and stronger (ㅆ) sound. ㅆ sounds like an English [s] sound pronounced with more force in your mouth ("tensing") than usual. ㅅ is softer, somewhat like the [sh] sound in English even though they are clearly not the same.
The [sh] sound is made by activating the sides of the mouth and tongue, and this seems to reduce the vocal energy. So it is like English has a full normal sound (s) and a soft lateralized sound (sh), whereas Korean has a similar full normal sound (ㅆ) but a non-lateralized soft sound (ㅅ) instead of English's lateral/lispy sound.
To help distinguish ㅅ from ㅆ, note that to a Korean ear [sh] sounds like 쉬 or 슈, meaning it comes off like ㅅ except that we seem to hear a vowel-like component like ㅟ (similar to "wee") or ㅠ ("you") mixed in. If you can make the [s] sound of "sign" much softer like the beginning of "shine" without activating the sides of the mouth, then you probably have a pretty accurate ㅅ sound.
