(CNN) -- Sometimes we hear what we want to hear.
In "Annie Hall," Woody Allen's Alvy Singer is convinced that anti-Semitism lurks around every corner.
"I distinctly heard it," he tells Tony Roberts' character, and then digresses into a story about hearing a companion say "Jew eat?" -- instead of "Did you eat?"
"You see conspiracies in everything," responds Roberts.
In the Trayvon Martin case, the spoken word has become part of the controversy about what really happened. And despite the fact that we live in an era when computers can break down syllables with split-second ease, interpreting the spoken word can remain challenging: noise, audio quality, even dialect can play a role, says Brian Joseph, a linguistics professor at The Ohio State University.
Moreover, much of our interpretation of language relies on context, he adds.
"A lot of what we do in understanding speech is we make predictions. These are all unconscious and very rapidly done," he says. "But we make predictions about what we are going to be hearing based on what we have already heard, and the context in which we are listening."
With the Martin case, the debate has turned on what George Zimmerman said when he was on the phone with 911 operators in the moments before he shot Martin. Zimmerman told his lawyers that he whispered "punks," not a racial slur, his attorneys told CNN on Thursday.
Some commentators have said they hear a racial slur, and others say there is no way of knowing. Jon Stewart mocked the coverage on "The Daily Show."
Forensic audio expert Tom Owen, who analyzed the 911 recordings, stated the garbled word that raised controversy was "punks," not the racial slur some people said they heard.
When Owen, chairman emeritus of the American Board of Recorded Evidence, used a computer application to remove cell phone interference, the word became clearer, he said. After discussions with linguists, he said he became convinced that Zimmerman said "punks."
He provided CNN with a copy of the newly processed audio.
CNN also enhanced the sound of the 911 call, and several members of CNN's editorial staff repeatedly reviewed the tape but could reach no consensus on whether Zimmerman used a slur.
The 'mom' bomb
Misunderstood speech can lead to problems in other fields. The military has a phonetic alphabet so instructions aren't confused: M and N, two letters easily misconstrued, become "Mike" and "November." Pilots strive for clarity in their communications with air-traffic controllers and crew -- after all, safety is at stake.
Even casual chatter can be misinterpreted. In one recent case, a pilot welcomed the mother of an air-traffic controller on his flight -- except some passengers believed he'd said there was a "bomb on board," and not a "mom on board." Two passengers complained to officials.
"A lot of these misunderstandings are not a matter of willful misunderstanding. They kind of just happen," says Joseph.
In music and poetry, these misinterpretations have come to be known as mondegreens. " Excuse me while I kiss this guy," some people think they hear in Jimi Hendrix's "Purple Haze." "You and me and Leslie, groovin'," the Young Rascals did not sing in "Groovin'." "Wrapped up like a douche, another runner in the night," went (allegedly) Manfred Mann's Earth Band's version of Bruce Springsteen's "Blinded by the Light."
(The actual lyrics are, of course, " Excuse me while I kiss the sky," "You and me endlessly, groovin' " and "Revved up like a deuce.")
When the "Paul McCartney Is Dead" rumor went around in 1969, Beatles fans ran their phonographs into the ground by playing their LPs backwards and at awkward speeds. Did John say "I buried Paul" at the end of "Strawberry Fields Forever"? Did the group say "We'll f*** you like supermen" at the end of the "Sgt. Pepper" run-out groove? And what of the White Album's "Revolution 9"? More than 40 years later, whole websites are still devoted to figuring it out.
For all the problems they cause, our understandings of speech are actually beneficial, points out Joseph, the Ohio State linguistics professor.
"The ability to predict makes it easy for us to understand rapidly -- within milliseconds you are understanding what I'm saying," he says. "Part of that is because you can project ahead and you can draw on your experience in having listened to people talk for however many years."
In the Martin case, the word may make a difference. Some observers are calling for Zimmerman to be charged with a hate crime, and his speech could be used as evidence.
But then again, words and speech always make a difference. They help illustrate the way we think, Joseph says.
"The kinds of semantic associations people make that lead to speech errors give you an idea of the kinds of connections that people forge," he says.
He adds that speech can also make you re-think.
"When you hear something that goes counter to your expectations, either you have to go back and say, 'What did I just hear?' " he says. "Or else you recalibrate and say, 'We're moving in a different direction.' "