Revisiting Neil Armstrongs Moon-Landing Quote: Implications for Speech Perception, Function Word Reduction, and Acoustic Ambiguity.

Melissa M Baese-Berk,Stephanie Schmidt,Laura C Dilley,Tuuli H Morrill,Mark A Pitt,Ian Mcloughlin

doi:10.1371/journal.pone.0155975

Abstract

Neil Armstrong insisted that his quote upon landing on the moon was misheard, and that he had said one small step for a man, instead of one small step for man. What he said is unclear in part because function words like a can be reduced and spectrally indistinguishable from the preceding context. Therefore, their presence can be ambiguous, and they may disappear perceptually depending on the rate of surrounding speech. Two experiments are presented examining production and perception of reduced tokens of for and for a in spontaneous speech. Experiment 1 investigates the distributions of several acoustic features of for and for a. The results suggest that the distributions of for and for a overlap substantially, both in terms of temporal and spectral characteristics. Experiment 2 examines perception of these same tokens when the context speaking rate differs. The perceptibility of the function word a varies as a function of this context speaking rate. These results demonstrate that substantial ambiguity exists in the original quote from Armstrong, and that this ambiguity may be understood through context speaking rate.

Highlights

“That’s one small step for man, one giant leap for mankind.[1]” Neil Armstrong insisted for years that his famous quote upon landing on the moon was misheard, and that he had said “one small step for a man” [2]
The disagreement about what Armstrong said during his transmission from the moon stems partly from several acoustic and spectral characteristics of function words like a; they can be quite short in casual speech, consist of just a few pitch periods, and be spectrally indistinguishable from the preceding context [4,5]
Context speech rate may be an even more important cue for listeners. This prior research suggests that the case of ambiguity in the famous quote by Armstrong represents the perfect storm of conditions for misperception; though a function word may have been spoken, it was not perceived due to a number of factors, including possible reduction and coarticulation of for a, in addition to an ambiguous syntactic context

Summary

Introduction

“That’s one small step for man, one giant leap for mankind.[1]” Neil Armstrong insisted for years that his famous quote upon landing on the moon was misheard, and that he had said “one small step for a man” [2]. The disagreement about what Armstrong said during his transmission from the moon stems partly from several acoustic and spectral characteristics of function words like a; they can be quite short in casual speech, consist of just a few pitch periods, and be spectrally indistinguishable from the preceding context [4,5] This phenomenon is known more broadly as speech reduction. Context speech rate may be an even more important cue for listeners This prior research suggests that the case of ambiguity in the famous quote by Armstrong represents the perfect storm of conditions for misperception; though a function word may have been spoken, it was not perceived due to a number of factors, including possible reduction and coarticulation of for a, in addition to an ambiguous syntactic context. Similar to the case of Armstrong’s original phrase, in which a slow surrounding context speech rate results in a short duration of the phrase for (a) relative to its context, we hypothesized that when tokens of speech including a reduced string of for a had context speech slowed down relative to the for a, the function word a would be less likely to be reported

Methods

Results and discussion

Results and Discussion

General Discussion