In scene one when the audience is first introduced to Laura the stage directions show that "the interior has lit up softly and through the scrim we see Amanda and Laura..." This promotes to the audience the significance of an aspect of the stage when the lighting is intensified, in this case the central character in the play, Laura is now on stage.
Towards the end of the scene Amanda is questioning Laura on whether she will have any gentlemen callers. After Laura insists that there won't be any she laughs nervously at her mothers response. At this moment the stage directions state, "a shaft of very clear light is thrown on her face against the faded tapestry of the curtains". This bold amount of light is significant compared to the dim light usually established in the play. It is seen as significant in the play that Laura slips through the portières, and the light on her face makes the audience aware that Laura's actions are significant in Tom's memory.
Throughout scene one the lighting upon characters is associated with music. During the scene Tom motions the stage directions to place "a pot of light on Amanda" and he also motions for music. Also at the close of the scene the light "dims out the 'Glass Menagerie' music". This use of music throughout the play illustrate to the audience the emotion behind the memory being portrayed by Tom, but it also distances the play from reality, again signifying that the play is non-realistic. The music played throughout the play is light music, which expresses a delicate but also sad feel. This light music relates to glass, which becomes a motif for Laura in the play. There is beauty about it, but also the tendency for it to be so easily broken.
Throughout the scene music is often played during a characters dialogue. During Amanda's speech the stage directions indicate for the music "'The Glass Menagerie' under faintly. Lightly". This use of music can be seen to express emotion on what the person is saying, but it could also express satire towards the character. The music of 'The Glass Menagerie' sounds similar to clown music, which is often associated with hiding behind something the character is not, which is a mockery for Toms life and his memory.
Therefore, the use of music and lighting in the play is significant in portraying to the audience the depth and importance of Toms memories, but also reminding the audience that what they are viewing is just a memory, which is subjective to Toms thoughts and opinions.
http://www.youtube.com/watch?v=KUnS1mK9ibo - The Glass Menagerie Music