The music that they sing and the music in the background and the type of mask they wear also go together with the mood and atmosphere, as the situations develop. Like in Oedipus Rex, the chorus of the classical Greek theater would consist of representative citizens of the society which the drama was supposed to represent. Through the dramatic performance, they would occupy the central circular place called orchestra. The Chorus would not only act as spectators and careful Observers but also as, commentators of the dramatic procedure. It took the issue of the changing situations and developments, and expressed its comments mostly in the form of songs that were called odes. The Chorus used to be allowed its say at the moment of acute need. When the spectators would feel uncertainty of the situation, the Chorus guided them with the appropriate kind of feelings and attitude towards the events in the theater. In Elizabethan drama the chorus consisted of only a single character whose role was to comment on the action of the play, prologue or epilogue. The chorus is no longer used as a rule in the modem theater, but in some plays that use it, it is a group of singers and dancers who provide a suitable accompaniment for the action of a musical play.
The basic role of the chorus in Oedipus Rex is to sing comments about the ongoing situations in the drama. This chorus, which consists of a group of mature old Theban people, which is highly reliable, as commentators, serves to make significant dramatic commentary that guides the audience's response from the beginning to the end of the plot. The functions of the chorus in this play can be categorized into five headings: 1) mediating, 2) evaluating, 3) foreboding, 4) guiding, and 5) dramatizing.
1. The most important role of the chorus in this play is to mediate or play the role of middlemen between the imaginary world of the drama and the real world of the audience. They mediate in terms of space and in terms of understanding. Because the scene (stage) was too far away from the immense theatron (seeing place), the chorus had to play the role of coming in between the two places and making the audience overhear them more easily. They sang aloud commenting on the dramatic actions and situations moving towards the audience and going round the orchestra (their dancing place in between the stage and the stadium). But besides filling the gap of space, they also came in between (mediated) the audience in terms of understanding. Because the Greek audience should have been simple people, the chorus had to comment and make explicit certain things and themes that developed in the dramatic world. The simple audience would be able to understand the dramatic world more easily with the help of the choric commentary.
2. Another important role of the chorus was to comment and evaluate the incidents and developments, characters and themes of the drama. In the present drama, the chorus comments on the fall of Oedipus, on his greatness, on his weakness, and in general in the destiny and frailty of man. Without their comments, the drama would have lost much of the meaning and perspective that Sophocles wanted to convey to his audience. Besides, the commentary creates appropriate mood and atmosphere of the play. Sophocles' theme of fatalism is finally reinforced by the realization of the wise old people of Thebes (the chorus) who at last surrender before the forces of fate and the gods.
3. The chorus usually seems to suggest what is going to happen next, thereby suggesting to us to get ready and accept things as they happen. The forebodings (suggestion of what will happen in the future) of the chorus are however not always reliable. This keeps the dramatic tension intact. We feel that the chorus is a fully reliable group of wise old men, and even think that they can know the future or the truth of anything. But, we see that they are changing and learning, much like ourselves.
4. The chorus also plays the role of guiding our emotions, response, and our understanding. They tell us what to feel, what to say and how to look at and evaluate what happens on the stage. They express the appropriate kind of feeling whenever any important development or discovery takes place in the world of the characters.
5. The chorus also dramatizes the process of the drama. They help the characters prepare by letting some time pass. This also allows the audience to prepare themselves for the next scene. But, most importantly, the chorus dramatizes their own development. They sometimes think and doubt, wish and expect the wrong. They are much like us, as they are undergoing the process of being educated and enlightened by the experience of the reality of life. In the beginning they only express some faith in the gods, but they disbelieve and even disregard the prophecy of Teiresias by saying that "these evil words are lies". Then they begin to fear the law of the gods and express that fear, warning us also that the disobedience of the divine laws brings about doom. In the third ode, they express a false wish that Oedipus were the son of the gods, but they do emphasize that we can never see the future. At last, they fully change and purify themselves directing our process of change also. In the fourth ode, they finally realize the ultimate reality that fate rules us absolutely. They pity and fear the plight of Oedipus, and they help us have the catharsis. Their comment is thematic and it dramatizes the full development of their growth: they are now enlightened. That embodies the dramatic effect intended for the audience also.
The chorus appears five times in Oedipus Rex, and each ode they sing makes a reflection upon each climatic situation. The first song of chorus sound immediately after Oedipus has declared his resolution to trace the murderer of Laios. The chorus has already learnt the message from Delphi and consequently expressed uncertainly about who the murderer might be. The choric song also intensifies the sorrowful condition prevailing in the city. Sickness has our powered the city like an epidemic and no remedy is available. The second song is introduced just after Oedipus is accused of being a murderer himself. The chorus is not prepared to believe the allegation against Oedipus and instead urges the horrible murdered to free from the city immediately. The third song is a meditation upon a serious defect of Oedipus's nature. In his dealing with Creon, Oedipus has exhibited extreme pride, arrogance and ill-temper. The chorus indirectly speaks of the possible fall of tyrants through pride. The fourth ode comes up while Oedipus is occupied by the crisis of his identity. The chorus speculators on some romantic affair between gods and nymphs on the mountain side and assume that Oedipus must be such semi-divine product. The final choric song is an interpretation of Oedipus's fall and reflection upon short-lived happiness of human beings. The choric songs thus intensify and analyze the developing dramatic situation helping the audience to understand the drama more fully.