Harbour tells PEOPLE the surprising truth behind Ryder's reaction to his SAG Awards acceptance speech

While accepting the 2017 Screen Actors Guild award for outstanding performance by an ensemble in a drama series last month for Stranger Things, Winona Ryder made headlines (and inspired many memes) when she reacted to costar David Harbour’s impassioned speech with a variety of facial expressions. And now, Harbour is revealing the real reason Ryder reacted the way she did on stage.

“She couldn’t hear me!” Harbour, 41, told PEOPLE at the Writers Guild Awards in New York Sunday night. “Which I was confused by, because I was screaming! But apparently, she couldn’t hear me.”

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Harbour plays police chief Jim Hopper in the acclaimed sci-fi Netflix series while Ryder plays Joyce Byers, mother to a missing 12-year-old boy.

The Shrine Auditorium’s acoustics may have been partially to blame, but Harbour added of his costar, “She is just such a porous, expressive woman and actress — I think it just flowed through her like every experience — and I loved it.”

The actor said that he ran the speech by several co-stars (not including Ryder), and spent a week writing multiple iterations — but despite his prep work, there were still some things time didn’t allow him to touch on — one being the way women are perceived in the industry.

“A lot of Hollywood female characters are not treated as ‘bad ass’ — I wanted to talk about that … the women characters in our story that have such power.”

In addition to Ryder, Harbour stars alongside fan-favorites Millie Bobby Brown, Shannon Purser and Natalia Dyer in the series.

And while the internet was sent into a tizzy with Ryder’s meme-worthy reaction, many in the audience met Harbour’s words with a roar of applause.

2017 Comic-Con Portraits
Credit: Robby Klein/Getty

“Out of the corner of my eye, I see Denzel [Washington] and Meryl Streep standing up,” he recalled. “The reason why I was shaking and everything was I just couldn’t believe that was my life at that moment. These are people who I’ve grown up with and people that I’ve admired my whole life. To be considered among them, or a part of them, was the greatest moment.”

His nearly two minute speech (he joked about going over his allotted 45 seconds) that touched on fighting bullies and protecting the marginalized was thought by some to have political undertones, but Harbour saw it as more than that.

“What I was really trying to say in the speech was not so much political as it was cultural,” he said. “I feel like [actors] do have a responsibility as influencers in this culture that creates good or evil. We have a responsibility and we should be aware of that — that is really what I wanted to talk about.”