Sounds That Grate
Feb 06, 2007
Sounds That Grate
If the mere mention of fingernails on a blackboard makes you flinch, you may want to skip this story. We'll be merely mentioning that a lot.
Last week when President Bush explained his use of the term "Democrat Party" -- without the Democrat-preferred "-ic" -- in his State of the Union message, he said he hadn't intended to rile anyone up. "I didn't mean to be putting fingernails on the board," he told National Public Radio.
In making his remarks, the president may not have recognized that he was dabbling in the field of psychoacoustics, the study of human response to audible stimuli. Pyschoacoustics has contributed to our understanding of music and is used in crafting optimal workplace conditions and all manner of other helpful endeavors. Yet it has shed precious little light on one of mankind's most enduring questions: Why do fingernails on the blackboard make so many of us cringe?
Turns out few have even tried to find out.
As it happens, the president's comment closely followed the Jan. 24 release of a British survey tallying results of a worldwide poll ranking the most awful of awful sounds. Trevor Cox, an acoustics professor at the University of Salford, established a "BadVibes" Web site ( http://www.sound101.org) that invited people to rate the horribleness of 34 sounds, ranging from the squeak of Styrofoam (polystyrene, in the study) to the squeals of many babies. More than a million votes were cast and, in an upset, fingernails-on-the-blackboard came in a pathetic 16th place, inducing far less rancor than the top winner (loser?): the sound of someone vomiting.
Cox surmises that we recoil from revolting-bodily-function sounds because we're hard-wired to retreat from situations -- the spread of pathogens, for instance -- that might make us sick. In the case of vomit, hearing the dulcet tones of another's retching might lead us to follow suit to rid our bodies of the same thing that made the other person sick.
As for fingernails, Cox advances several theories. Scraping noises might bother us because we imagine how lousy it feels to perform the scrape-inducing activity -- our own fingernails on the blackboard, our own Styrofoam rubbing against the cardboard box. "There's something fundamental about the sound," he says, "and I don't think it's just about teachers torturing kids." He guesses that there's something inherent in the fingernail-on-board scrape that gets under our skin and that "fingernails on a blackboard is just a common way to deliver that sound."
The primary study on the matter, "Psychoacoustics of a Chilling Sound," appeared in 1986 in the journal Perception & Psychophysics. One of the authors, Randolph Blake, now a professor of psychology at Vanderbilt University, says the study happened almost by accident: The scientists set out to conduct a study of negative visual stimuli but found sound easier to work with than images.
One of the study's findings: Contrary to what you might expect, it's not the higher-frequency components of the composite fingernails/blackboard sound that irk us. Eliminating those high-pitched tones and isolating the sound's midrange components created the most squirm-inducing sound among the dozen or two students and faculty members who were put to the test.
The authors speculate that our response derives from behavior observed in other primates. The warning screams of macaques are acoustically similar to nails on a blackboard, they note, suggesting that our reaction is perhaps a vestige of our natural response to such a signal. A 2004 study in the journal Cognition cast doubt on this notion, finding that tamarins reacted less strongly to a scraping noise than did humans in the study. These were a different species of primates, though, so the jury's still out.
The most serious recent effort to explore skeevy sounds has come from David Zald, an assistant professor of psychology at Vanderbilt. In Zald's research, published in 2002 in the journal NeuroImage, PET scans of the brain documented increased activity in the amygdala, the deep-set portion of the brain that regulates autonomic, or bodily, responses to stimuli, among participants listening to "aversive" sounds -- including you-know-what on the you-know-what.
For his part, Cox has moved to happier pastures: He's now gathering responses to pleasant sounds and expects to release findings late this year. Both Blake and Zald would like to see someone study the fingernails phenomenon further. But such an undertaking would face several daunting obstacles.
"It's an interesting scientific question," Zald says. "But I think part of the reason it hasn't been taken up is that I'm not quite clear how someone would pitch it in terms of funding." Plus, Zald adds, it might be hard to find participants willing to subject themselves to the odious sounds.
Cox notes another potential obstacle: In this era of whiteboards and Smart Boards, you'd be hard-pressed, he says, "to find a blackboard in a university these days."
If the mere mention of fingernails on a blackboard makes you flinch, you may want to skip this story. We'll be merely mentioning that a lot.
Last week when President Bush explained his use of the term "Democrat Party" -- without the Democrat-preferred "-ic" -- in his State of the Union message, he said he hadn't intended to rile anyone up. "I didn't mean to be putting fingernails on the board," he told National Public Radio.
In making his remarks, the president may not have recognized that he was dabbling in the field of psychoacoustics, the study of human response to audible stimuli. Pyschoacoustics has contributed to our understanding of music and is used in crafting optimal workplace conditions and all manner of other helpful endeavors. Yet it has shed precious little light on one of mankind's most enduring questions: Why do fingernails on the blackboard make so many of us cringe?
Turns out few have even tried to find out.
As it happens, the president's comment closely followed the Jan. 24 release of a British survey tallying results of a worldwide poll ranking the most awful of awful sounds. Trevor Cox, an acoustics professor at the University of Salford, established a "BadVibes" Web site ( http://www.sound101.org) that invited people to rate the horribleness of 34 sounds, ranging from the squeak of Styrofoam (polystyrene, in the study) to the squeals of many babies. More than a million votes were cast and, in an upset, fingernails-on-the-blackboard came in a pathetic 16th place, inducing far less rancor than the top winner (loser?): the sound of someone vomiting.
Cox surmises that we recoil from revolting-bodily-function sounds because we're hard-wired to retreat from situations -- the spread of pathogens, for instance -- that might make us sick. In the case of vomit, hearing the dulcet tones of another's retching might lead us to follow suit to rid our bodies of the same thing that made the other person sick.
As for fingernails, Cox advances several theories. Scraping noises might bother us because we imagine how lousy it feels to perform the scrape-inducing activity -- our own fingernails on the blackboard, our own Styrofoam rubbing against the cardboard box. "There's something fundamental about the sound," he says, "and I don't think it's just about teachers torturing kids." He guesses that there's something inherent in the fingernail-on-board scrape that gets under our skin and that "fingernails on a blackboard is just a common way to deliver that sound."
The primary study on the matter, "Psychoacoustics of a Chilling Sound," appeared in 1986 in the journal Perception & Psychophysics. One of the authors, Randolph Blake, now a professor of psychology at Vanderbilt University, says the study happened almost by accident: The scientists set out to conduct a study of negative visual stimuli but found sound easier to work with than images.
One of the study's findings: Contrary to what you might expect, it's not the higher-frequency components of the composite fingernails/blackboard sound that irk us. Eliminating those high-pitched tones and isolating the sound's midrange components created the most squirm-inducing sound among the dozen or two students and faculty members who were put to the test.
The authors speculate that our response derives from behavior observed in other primates. The warning screams of macaques are acoustically similar to nails on a blackboard, they note, suggesting that our reaction is perhaps a vestige of our natural response to such a signal. A 2004 study in the journal Cognition cast doubt on this notion, finding that tamarins reacted less strongly to a scraping noise than did humans in the study. These were a different species of primates, though, so the jury's still out.
The most serious recent effort to explore skeevy sounds has come from David Zald, an assistant professor of psychology at Vanderbilt. In Zald's research, published in 2002 in the journal NeuroImage, PET scans of the brain documented increased activity in the amygdala, the deep-set portion of the brain that regulates autonomic, or bodily, responses to stimuli, among participants listening to "aversive" sounds -- including you-know-what on the you-know-what.
For his part, Cox has moved to happier pastures: He's now gathering responses to pleasant sounds and expects to release findings late this year. Both Blake and Zald would like to see someone study the fingernails phenomenon further. But such an undertaking would face several daunting obstacles.
"It's an interesting scientific question," Zald says. "But I think part of the reason it hasn't been taken up is that I'm not quite clear how someone would pitch it in terms of funding." Plus, Zald adds, it might be hard to find participants willing to subject themselves to the odious sounds.
Cox notes another potential obstacle: In this era of whiteboards and Smart Boards, you'd be hard-pressed, he says, "to find a blackboard in a university these days."