Whomever it was Streisand had in mind is not someone we'd know of with certainty, but what's obvious is that she had someone in mind. Note that when the camera moved to the audience and focused on one of its members, that that woman connected to her own life experience, not Streisand's life experience. Did that woman say to herself, when she bought her ticket, "Oh, my, I'm going to Streisand's concert soon; I must go over all my romantic experiences in order to be able to find my substitutions and connect with my emotions!"? Regardless of the story, what makes a member of the audience spontaneously laugh, cry, get angry, remember an event, etc.? Isn't it a connection to the ideas/images they hear? That's why I suggest diving head first into the character's actions because how and if they will resonate for you will be discovered by trusting that it's somewhere there in your body. Both Hagen and Adler suggested, in writing, to seek a substitution only if all else failed.
Here's Sarah Vaughan with the same song and a different life experience. She moves me with every song I've heard her sing because she seems to combine her words with the musical notes in a particular way that vibrates, illuminates, the idea/images she needs to convey.
And another one -- ah, the angst we'd need to go through dredging up memories days, hours, before taking a comfortable seat, seeing who's in the audience, pleased we dressed appropriately for the occasion, and then again, preparing our painful memories in order to participate in the audience's experience listening to:
