Neil Armstrong’s most famous line — “That’s one small step for man, one giant leap for mankind,” uttered after becoming the first person to set foot on the moon — contained one small error that became one giant annoyance to the NASA astronaut.

As Armstrong himself pointed out many times, the sentence is meaningful only if he says, “That’s one small step for a man.” He insisted that’s what he said on July 20, 1969 – otherwise, there’s no distinction between a single individual and all of humanity.

“I think that reasonable people will realize that I didn’t intentionally make an inane statement and that certainly the ‘a’ was intended, because that’s the only way the statement makes any sense,” Armstrong told biographer James Hansen, according to “Moonshot,” a terrific book about Apollo 11 by Brian Floca.

Experts have scrutinized the audio file of Armstrong’s historic transmission, searching for evidence of the missing “a.” Those efforts “have yielded mixed opinions,” according to a research team that weighs in on the controversy this week.


A team led by Laura Dilley, an assistant professor in the department of communicative sciences and disorders at Michigan State University, has taken a new approach to analyzing this historic sentence. The team studied the way that folks in Ohio pronounce the word “for” and the phrase “for a.”

In central Ohio, where Armstrong was raised, speakers have a tendency to blend the two words together. And previous studies of Armstrong’s own speech “have established well that if the word ‘a’ was spoken, it was very short and was fully blended acoustically with the preceding word,” Dilley said in this story by Michigan State University Today. Coming out of Armstrong’s mouth, the phrase “for a” would have sounded like “frrr(uh),” according to the story.

So Dilley and her colleagues turned to recordings of 40 people raised in Columbus, Ohio, about 90 miles southeast of Armstrong’s native Wapakoneta. The recordings, part of the Buckeye Speech Corpus, included 191 cases of the phrase “for a.”

It turned out that the length of the “r” sound was much the same when Ohioans said “for” and “for a” — a finding that seems to confirm Armstrong’s version of events.


“We’ve bolstered Neil Armstrong’s side of the story,” Dilley told MSU Today. “We feel we’ve partially vindicated him. But we’ll most likely never know for sure exactly what he said based on the acoustic information.”

However, Dilley also noted that regardless of what Armstrong actually said, people are still more likely to hear the sentence without the crucial “a.”

The research team will present the results Friday morning at the International Congress on Acoustics meeting in Montreal. The study was funded by the National Science Foundation.

