The Silence

Two emotionally estranged sisters, Ester (Ingrid Thulin) and Anna (Gunnel Lindblom), and Anna's son, Johan (JÃ¶rgen LindstrÃ¶m), a boy of 10, are on a night train journey back home. Ester, the older sister and a literary translator, is seriously ill. Anna coldly assists her, seemingly resenting the burden. They decide to interrupt the journey in the next town called "Timoka", located in a fictitious Central European country with an incomprehensible language and on the brink of war.
The sisters rent a two-room-apartment in a once-grandiose hotel. Ester suffers in her room, self-medicating with vodka and cigarettes while trying to work. Johan soon begins wandering around the hotel's hallways, encountering the elderly hotel porter and a group of Spanish dwarves who are part of a traveling show. Meanwhile, Anna ventures into the city and is openly advanced upon by a waiter in a cafe. Later, she watches a show in an uncrowded theatre, and is both repelled and fascinated when a young couple begin to have sex in a seat nearby. Anna returns to the cafe, brushes past the waiter, and returns to the hotel in time.
Left with Johan while his mother is out, Ester attempts to form a more intimate bond with him, but Johan avoids her attempts to stroke his hair and face. On Anna's return, Ester is eager for an account of what her sister has done after seeing her soiled dress. Provoked, Anna spitefully fabricates a sexual encounter with the waiter to her sister. Anna also reveals her intention to meet him again that evening, which Ester, not wanting to be left alone, begs her not to do.
Anna meets the man in their hotel, and Johan witnesses them kissing and entering a room down an adjacent hall. Upon returning to the room, he asks Ester, why his mother dislikes being with them, as she always departs as soon as she gets the chance. Ester tells him that she has learned a few words of the local language, and she promises to write them down for him. Johan, instinctively knowing Ester is seriously ill, embraces her in a show of concern and compassion.
After Johan has fallen asleep, Ester sobs at the door of Anna and her lover, asking to come in. Anna lets her in and turns on the lights so that Ester can fully see the two of them in bed together. Anna tells Ester that she once aspired to be like her, morally elevated, but realized that her apparent goodness was actually a reflection of Ester's hatred of Anna and all that belonged to her. Ester insists that she loves her and that Anna is wrong. Anna gets furious and asks her to leave the room. On leaving, Ester says "poor Anna", enraging her even more. Anna's lover advances upon her again; Anna is laughing hysterically, but it turns into sobs.
The next morning, Anna announces that she and Johan are going to leave the hotel after breakfast. Ester deteriorates while they are gone, having painful spasms of suffocation. She is helped by the elderly porter, who attempts to comfort her; she reveals her fear of death and loneliness but also her loathing for sexual contact. When Johan returns to say good-bye, Ester gives him a note. After he and Anna have boarded the train, Johan reads the title: "To Johan â words in a foreign language". Uninterested, Anna opens the window and cools herself with the outside rain.

Question: Who sobs at the door of Anna and her lover?
Answer: Ester