When a particle is omitted in casual speech, the written representation (to my great surprise) adds a comma. Do these commas actually correspond to any change or pause in the intonation?
テニス、する? 今、何、してる? どんな食べ物、好き?
Also, are these commas required or optional?
EDIT:
The source of this information is the textbook「上級へのとびら」. While there is no direct statement in the book that the commas act as a replacement for the omitted particles, in the multiple example sentences as well as in a table of examples for several levels of speech, the comma 「、」 is in fact used as a replacement for the omitted particles in every case.
Example dialog:
A: 「あ~、お腹、すいたなあ」
B: 「俺{おれ}も腹へった。この辺にうまいトンカツの店があるんだぜ。食{く}いに行こうか。おごるよ」
A: 「いやよ、トンカツは。カロリーが高いから」
B: 「なんだ、じゃ、俺{おれ}、一人で行こうっと」
A: 「あ、まって! その店、おいしいんでしょ。やっぱり、私も行くわ!」
B: 「じゃ、今から行くぞ!」
(You can hear the example dialog in this official audio transcript, from the minute 3:30)
Table of examples for each level of speech (see the third column くだけた言い方):
Unfortunately, there is no audio transcript for the contents of the table above.