Cardboard drink tray boombox styled by Waterloo audio researcher

The McDonald's promotional event has come and gone, but a lot of science and math from a Waterloo audio expert went into the drink tray boombox - a cardboard sleeve that turns the tray into a smartphone speaker.

McDonald’s promotional cardboard sleeve got sound tweak from Waterloo audio expert

Janelle Resch, a researcher at the University of Waterloo's Audio Research Group, helped develop the boombox for McDonald's. (Kate Bueckert/CBC)

Cardboard drink trays from takeout restaurants usually end up in the garbage or recycling bin.

But acoustical math from a Waterloo audio expert recently helped create a promotional item that has some sound implications.

At a recent event recent in Toronto, McDonald's restaurants distributed a cardboard cover for the tray, turning it into a smartphone boombox speaker.

And it was Janelle Resch who fine-tuned the creation to make portable music sound better.

Janelle Resch is a Ph. D candidate at the University of Waterloo and part of the school’s Audio Research Group. (Jackie Sharkey/CBC)
Resch, a Ph. D candidate at the University of Waterloo and part of the school's Audio Research Group, was brought on by Toronto company Stacklab to help craft the boombox. It slides over a drink tray, amplifying music and sound from your smartphone's tiny speakers.

Resch, whose research into brass instruments such as trombones and trumpets often seems abstract and conceptual to people, was able to make complex calculations into the nature of sound and apply them to something portable and practical.

"It was really nice to take the things that I've been studying and learning and apply it to something that I could physically make that other people would use," she said. 

Her tweaks included adding a metallic coating inside the cardboard speaker cones to reflect, rather than absorb sound. And her calculations also led to the cones being 10 sided, rather than than the six originally proposed.

Audible differences

In a field test with CBC K-W, Resch demonstrated how the nature of sound changed when coming from a cellphone alone, compared with one in a drinking glass and one in the drink tray boombox.

When the phone was placed in a glass or mug — a trick often used by people to boost the sound — the audio is amplified but muffled by its own reflections.

"It's very echoy: you can hear a lot of the bouncing going around and that's because the cup is cylindrical," Resch explained.

The sound coming from the boombox is clearer.

"The biggest difference is probably the fidelity. This is more clear. You don't hear the same sort of bouncing around of sound [and the mug has] almost a delay," she said.

Resch used an audio spectrogram display to illustrate the difference. 

The sound from the glass was louder than the sound from a phone by itself, but not all frequencies were amplified to the same volume. The boombox was louder throughout the entire frequency range.
The McDonald's boombox amplifies sound better than putting it in a cup, sound researcher Janelle Resch says. (Kate Bueckert/CBC)

Way to reach all ages

Resch said she enjoyed partnering up with McDonald's because the boombox would reach many different people.

"It was also really exciting because promoting STEM — science, technology, engineering and math — for kids, for me, is a very important thing to do. You want to get them interested and everyone, at some point, has heard music," she noted.

"Music, I think, is a great way to get people interested in math — especially kids."

About 1,000 boomboxes were handed out by McDonald's at an event in Toronto in July for the McFlurry drink anniversary, the company's public relations supervisor Kristen Hunter told CBC News.

"We weren't really sure the type of response it was going to receive, but it was overwhelmingly positive," she said.

The bad news for people hoping to get one: McDonald's Canada has no plans to distribute anymore boomboxes in the near future.

"I don't want to say, 'never say never,' but currently [there are] no plans to distribute any further," Hunter said.


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