The benten, represented in our alphabet by an apostrophe, can represent the presence of a glottal stop in a word. Basic doesn't use glottal stops very much, so it isn't as intuitive to us, but one example of a glottal stop found in basic is the short pause you hear in the word, "uh-oh." If you pay close attention to the way your throat moves when you say uh-oh, you can feel how the air is cut off in the back of your throat. This is a glottal stop. There are many different kinds of "stops" your mouth regularly makes and which letter sound they make depends entirely on which part of your mouth is stopping the air from flowing. If you stop the air with your lips, it makes a "P" or a "B" sound. If you stop the sound with the tip of your tongue near or touching your upper teeth, it makes a "T" or a "D" sound. If you use the back of your tongue, it makes a "K" or a "G" sound (not the "J" sound). If you stop the air in your throat behind the "K" and "G" sounds, you make a glottal stop, which has no letter association in Basic.
Something that might help you picture this and feel the difference in your mouth is the following exercise:
If needed, I can post some youtube videos containing recordings of me practicing the above exercise so you can hear how it is supposed to sound as well as me saying a few common Mando'a words containing the benten sound (coincidentally, the word, "Mando'a" itself contains this sound).Start by saying, "uh-oh" except exchange the glottal stop with a P sound to say, "up-oh" instead. Now use T instead to say, "ut-oh". Now use K instead, "uk-oh". Finally, say "uh-oh" as you would normally. Hopefully this will teach your mouth that the glottal stop works just like these other letters except that it uses a different part of your mouth and using the benten sound will be feel more natural to you by association with these more common letters.
Sometimes a benten in a word represents a compound word, which is two words spliced together to make a new word, or it can be used with suffixes or prefixes. Whether or not the benten is pronounced (or even used) in these circumstances usually depends on the two letters the benten is location between.
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Do we need to be careful with this topic? Some of this material is almost verbatim the stuff in the files I downloaded from KT's site. Would it be better to link to her files on this? One way we could make this topic more "original" is to expand on it by giving descriptions, examples, and maybe even using the International Phonetic Alphabet.