Peggy wasn't entirely sure her lackluster knocks could even be heard over the booming sounds coming from within the room. She didn't need to press her face to the door to hear the wailing noise that was... perhaps singing? She thought it could have been an animal dying, but that would have been very rude to suggest.
She knocked again, louder this time.
Fortunately, good timing allowed it to be heard when there was a break in the instrumentals. An equally booming male timbre announced himself and she stepped back a little ways from the door when she heard movement coming towards her. She found the door pulled up to reveal a truly gigantic man.
If she was surprised or impressed at the sight of him, Peggy managed to conceal it fairly well. The first time she saw Steve Rogers emerged from the Vita-Ray Chamber, post-administrating of the Super Soldier Serum, had been a momentous occasion. Thor appeared to be even taller and more muscular, if that were possible. However, outside of a few blinks, Peggy was in no-nonsense 'agent mode' and schooled her features into a neutral expression as she politely confronted the figure of myth and legend.
"I'm afraid not, Mister... Thor. You asked that I inform you if I felt you were being too clangorous. As nice as it is of you to grace us with your... enthusiastic playing, I regret I must tell you it would be too loud if you intended to play on later into the evening."