Meaning of 'sob your heart out'

Test No. [color=blue]incompl/inter-44 “Speaking 1 (At the Theatre)”, question 7

The leading lady is also absent from our stage and you can probably hear her her heart out as I speak.

(a) sobbing
(b) soaking
© spitting
(d) calling

Test No. [color=blue]incompl/inter-44 “Speaking 1 (At the Theatre)”, answer 7

The leading lady is also absent from our stage and you can probably hear her sobbing her heart out as I speak.

Correct answer: (a) sobbing

Hi!!! I don’t get it!!! … you can probably hear her sobbing her heart out as I speak.
Answer, please
Many thanks
Pupil

Hi Pupil,

Here is the sentence you are referring to:

The leading lady is also absent from our stage and you can probably hear her sobbing her heart out as I speak.

The leading lady can not come out to the stage because she is crying too hard.[YSaerTTEW443543]

TOEIC listening, photographs: A hospital ward[YSaerTTEW443543]

Yes, to sob your heart out means to cry very hard.[YSaerTTEW443543]

TOEIC listening, photographs: Chefs in a kitchen[YSaerTTEW443543]