Katakana double consonant and extension
I'm learning Katakana, and am confused in the difference between a double-consonant symbol (ッ) and the extender symbol (ー). What is the functional difference in the way these are actually pronounced in words?

For example, take the word "slipper", written two ways:
スリッパ
スリーパ

Which way is correct? What is the difference in pronunciation between the two?

Thank you!@

Question

Katakana double consonant and extension
I'm learning Katakana, and am confused in the difference between a double-consonant symbol (ッ) and the extender symbol (ー).  What is the functional difference in the way these are actually pronounced in words?

For example, take the word "slipper", written two ways:
スリッパ
スリーパ

Which way is correct?  What is the difference in pronunciation between the two?

Thank you!@

Answer

「スリッパ」 is correct. "ッ" is pronounced like "get", "kick", "let" etc.
スリッパ is pronounced like surippa. Imagine "s + lip + a"
Meanwhile スリーパ is pronounced like suriipa. Imagine "sleep + a"
I hope it'll work for you. :)

Answer

Slipper is Surippa in Japanese.
Unfortunately,you can't use English spell.
So Japanese spell is スリッパ.

When a foreign language word is become a Japanese word,some customize has done.
1. Basically one letter(hiragana or  katakana) is pronounced by consonant+vowel or vowel so the word finished by consonant is added vowel forcibly.
(EX.baseball >> be-subo-ru) not finish by "L" ,finish by "U"which is vowel.
2. "L"  changes to "R".(EX. rock'n roll >> rokkun ro-ru) not  distinguish "L" and "R"
3. "V" changes to "B". Sometimes using "ヴ"for "V" but not common yet.(EX.glove >>guro-bu)
4. ”C” changes to "K".  or "T".(EX,comedy>>komedei*　*ヘボン式 cook >>kukku  ）
5.  Abbriviation      (EX, correspond>>コレポン (korepon)）