The listeners were then presented with the recordings, including slowed-down versions—because Armstrong’s speech was actually spoken quite slowly. Interestingly, results showed that more people heard “for” as opposed to “for a” when the either side of the phrase was itself slowed. This was probably because listeners expected all syllables to be lengthened proportionally, whereas the duration of the very brief “a” sound (which was relatively constant) became shorter in comparison to the lengthened syllables surrounding it.

So if Armstrong did say “for a,” it’s quite likely many of us would still hear it as “for” anyway, because of his accent, slow speech, and unclear recording. We still don’t know for certain what he said, but with these latest findings, the balance of probability now much more firmly supports his version of events.

Auditory illusions and other quirks

So does it matter? Not to Armstrong, who left the Earth for good on Aug. 25, 2012. However it certainly feels appropriate to reaffirm the legacy of someone who was a hero to so many.

It also illustrates some interesting speaking and hearing effects. Many dialects have short single-syllable words that fuse with the word before or after them when spoken, and yet are highly intelligible. Or consider the Australian accent that some believe to be derived from the heavy-drinking early settlement days as a kind of drunken drawl, leaving behind just the most essential parts of words. Most of us seldom speak words one-by-one anyway, and often flow our words into one another (relaxed pronunciation). Listening to accents or speakers we are familiar with, this works well, but can have amusing consequences when we listen to others.

Did you ever try to guess unclear song lyrics and get the meaning completely wrong? You are not alone. This is called a Mondegreen and turns out to be both frequent, as well as occasionally quite hilarious.

It is all due to the fact the human brain is amazingly good at filling in blanks by guessing information that is missing. If the brain does not recognize speech that it is hearing, it unconsciously searches for the closest match, and then “snaps” the meaning into place. We hear what the brain thinks is there, rather than what might actually be there. Auditory illusions, like optical illusions with sound, illustrate this.

For example, listen to these examples of sinewave speech, which are acoustic signals from sinewaves that vary in frequency in the same pattern as speech. When first hearing SWS, we understand nothing. But listen to the original version of the speech recording, then try again. Like magic, the sinewave speech is suddenly intelligible as the brain now “hears” it as speech.

Phantom words are another illusion which arises when we hear continually-repeated speech. They are the brain “grasping at straws” as it tries to extract additional meaning from the syllables being heard.

These are just a few of the exciting and fascinating aspects of speech, hearing, and brain research that come together in the field of psychoacoustics, which has given us MP3 musicmobile phone communications, and more great sound-producing products that are one giant leap ahead of 1969.

This post originally appeared at The Conversation.

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