# Psychologists Create Surprising Musical Illusion

The people in M.C. Escher's lithograph, "Ascending and Descending", seem to climb up and up a set of stairs, but keep returning to the same level where they started. This is an optical illusion. Could there be a similar musical illusion? Could someone design a musical scale that always seems to be going up in pitch but also goes all the way around to the beginning? Someone could, and did.

Diana Deutsch conducts research on the perception and memory of sounds. Some of this has inspired her to develop musical illusions, tricking people's ears in the same way artist M.C. Escher tricked people's eyes.

Deutsch, a psychologist from the University of California San Diego says that musical pitch can be thought of as linear, going from low to high, like the keys of a piano. On the other hand, she says, "pitch also has a circular component which is acknowledged in note names, so as you go up a keyboard you go C, C sharp, D, D sharp, E and so on then you get to A, A sharp, B then you get to C again and continue C sharp, D, D sharp, E and so on, so you go round and round a circle at the same time."

And every time the notes start repeating again, like from one C to the next, we have gone up an octave in pitch.

Building upon research by Roger Shepard and Jean-Claude Risset, Deutsch found a way to build a "staircase" of musical tones that seems to both go up without end, and just like in Escher's illusion, they appear to never go up to another octave. By changing the harmonics of each tone, Deutsch had in effect, turned a linear musical scale into a circle.

She explains that tones made by natural instruments are composed of many tones, called the harmonics or overtones. Each overtone has a frequency that is a multiple of a fixed base frequency, and so they can be numbered according to that: 1 for the base one, and then 2, 3, 4, 5, and 6. "So if you take the odd-numbered harmonics," Deutsch explains, "numbers 1, 3, and 5, and reduce them in loudness so that you end up with harmonics 2, 4, and 6, you end up perceiving the same note but an octave higher, and that forms the basis of this illusion." ()

Deutsch started with the G sharp that one would find in the middle of a piano keyboard, and as she descended note-by-note, she would lower the volume of the odd-numbered harmonics, until she got to A, which now sounded like it was an octave higher — just above the G sharp she started with — like in the example above.

After modifying the volume of the odd-numbered harmonics, Deutsch had a set of twelve tones. She played all the possible pairs of tones to her students and asked them to write down, for each pair, whether they were going up or down in pitch. They sounded like this. ()

The student listeners confirmed that changing the harmonics effectively created the musical illusion of a never-ending scale, even though it circled around to its starting point at the end of every octave.

"So when these tones are played just going up," says Deutsch, "note by note, you can hear what sounds like a scale that goes up and up and up and never returns to the beginning, or it can appear to be going down and down and down all the time and never returning to the beginning.

.

.

The scales appear to always be going up or down, and we can tell, if we play the first tones and the last tones, that we really never left the octave. () — beginning and end of circular scale going up

Deutsch also developed two gliding scales, where the notes go up or down smoothly. These seemed to have a psychological impact on listeners. She observes "people have been saying that listening to the ascending glide makes them feel sort of uplifted." A descending scale had a different effect. "I've played this to groups of students and I've found," Deutsch says, "after they've been listening to this descending pattern that they seem to be kind of nodding, and they have their eyes closed, and you can tell that they're feeling themselves sort of going down and down and down as though into a bottomless pit." She says she would like to explore these effects on people's moods more closely.

.

.

Diana Deutsch says that coming up with illusions is fascinating and fun, but she also believes that her research helps scientists understand how the brain processes musical pitch. Her new results were presented for the first time August 1 at the annual meeting of the Society for Music Perception and Cognition, in Montreal.

The psychologist says she wants to continue exploring how the human mind understands music and perhaps, in the process, find new and fun ways to keep tricking our ears.

This forum has been closed.

There are no comments in this forum. Be first and add one

### Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
After Paris Attacks, France Steps Up Fight Against ISi
|| 0:00:00
X
November 24, 2015 3:04 AM
The November 13 Paris attacks have drawn increased attention to Syria, where many of the suspected perpetrators are said to have received training. French President Francois Hollande is working to build a broad international coalition to defeat Islamic State in Syria and in Iraq. Zlatica Hoke reports.

#### After Paris Attacks, France Steps Up Fight Against IS

The November 13 Paris attacks have drawn increased attention to Syria, where many of the suspected perpetrators are said to have received training. French President Francois Hollande is working to build a broad international coalition to defeat Islamic State in Syria and in Iraq. Zlatica Hoke reports.

#### US, Cambodian Navies Pair Up in Gulf of Thailand

The U.S. Navy has deployed one of its newest and most advanced ships to Cambodia to conduct joint training drills in the Gulf of Thailand. Riding hull-to-hull with Cambodian ships, the seamen of the USS Fort Worth are executing joint-training drills that will help build relations in Southeast Asia. David Boyle reports for VOA from Preah Sihanouk province.

#### Americans Sharpen Focus on Terrorism

Washington will be quieter than usual this week due to the Thanksgiving holiday, even as Americans across the nation register heightened concerns over possible terrorist threats. VOA’s Michael Bowman reports new polling data from ABC News and the Washington Post newspaper show an electorate increasingly focused on security issues after the deadly Islamic State attacks in Paris.
##### Video

Heads of state from nearly 80 countries are heading to Paris (November 30-December 11) to craft a global climate change agreement. The new accord will replace the Kyoto Protocol on Climate Change that expired in 2012.

#### Uncertain Future for Syrian Refugee Resettlement in Illinois

For the trickle of Syrian refugees finding new homes in the Midwest city of Chicago, the call to end resettlement in many U.S. states is adding another dimension to their long journey fleeing war. Organizations working to help them integrate say the backlash since the Paris attacks is both harming and helping their efforts to provide refugees sanctuary. VOA's Kane Farabaugh reports.

#### Creating Physical Virtual Reality With Tiny Drones

As many computer gamers know, virtual reality is a three-dimensional picture, projected inside special googles. It can fool your brain into thinking the computer world is the real world. But If you try to touch it, it’s not there. Now Canadian researchers say it may be possible to create a physical virtual reality using tiny drones. VOA’s George Putic reports.

#### New American Indian Village Takes Visitors Back in Time

There is precious little opportunity to experience what life was like in the United States before its colonization by European settlers. Now, an American Indian village built in a park outside Washington is taking visitors back in time to experience the way of life of America's indigenous people. Carol Pearson narrates this report from VOA's June Soh.

#### Even With Hometown Liberated, Yazidi Refugees Fear Return

While the northern Iraqi town of Sinjar has been liberated from Islamic State forces, it's not clear whether Yazidi residents who fled the militants will now return home. VOA’s Mahmut Bozarslan talked with Yazidis, a religious and ethnic minority, at a Turkish refugee camp in Diyarbakır. Robert Raffaele narrates his report.

#### Nairobi Tailors Make Pope Francis’ Vestments

To ensure the pope is properly attired during his visit, the Kenya Conference of Catholic Bishops asked the Dolly Craft Sewing Project in the Nairobi slum of Kangemi to make the pope's vestments, the garments he will wear during the various ceremonies. Jill Craig reports.

#### Cross-Border Terrorism Puts Europe’s Passport-Free Travel in Doubt

The fallout from the Islamic State terror attacks in Paris has put the future of Europe’s passport-free travel area, known as the "Schengen Zone," in doubt. Several of the perpetrators were known to intelligence agencies, but were not intercepted. Henry Ridgwell reports from London European ministers are to hold an emergency meeting Friday in Brussels to look at ways of improving security.

#### El Niño Brings Unexpected Fish From Mexico to California

Fish in an unexpected spectrum of sizes, shapes and colors are moving north, through El Niño's warm currents from Mexican waters to the Pacific Ocean off California’s coast. El Nino is the periodic warming of the eastern and central Pacific Ocean. As Faiza Elmasry tells us, this phenomenon thrills scientists and gives anglers the chance of a once-in-a-lifetime big catch. Faith Lapidus narrates.

#### Terrorism in Many Forms Continues to Plague Africa

While the world's attention is on Paris in the wake of Friday night's deadly attacks, terrorism from various sides remains a looming threat in many African countries. Nigerian cities have been targeted this week by attacks many believe were staged by the violent Islamist group Boko Haram. In addition, residents in many regions are forced to flee their homes as they are terrorized by armed militias. Zlatica Hoke reports.

#### Study: Underage Marriage Rate Higher for Females in Pakistan

While attitudes about the societal role of females in Pakistan are evolving, research by child advocacy group Plan International suggests that underage marriage of girls remains a particularly big issue in the country. VOA’s Ayesha Tanzeem reports how such marriages leads to further social problems.