The sound of ab­so­lute si­lence

A room where sound goes to die, and sci­en­tists go to study.

The Star Malaysia - Star2 - - Science - By SANDI DOUGHTON

ANDY Pi­ac­sek swings open a bank vault­style door on what looks like a cham­ber of hor­rors.

Spiky wedges sprout from the walls and ceil­ing. Pi­ac­sek, a physics pro­fes­sor at Cen­tral Wash­ing­ton Univer­sity (CWU), United States, stands on the only flat sur­face: a metal grat­ing sus­pended above claw-like ser­ra­tions thrust­ing up from the floor.

In­juries are in­flicted here, Pi­ac­sek con­firms – but only to the oc­cu­pants’ mu­si­cal sen­si­bil­i­ties.

“It hurts my ears,” says Megumi Tay­lor, a flute player and stu­dent who joined Pi­ac­sek in the cham­ber on a re­cent af­ter­noon. “I don’t like the way it sounds in here.”

The 12-by-12-foot space is so quiet many peo­ple find it off-putting.

Thick walls and an in­ter­nal sus­pen­sion sys­tem that’s sep­a­rate from the rest of the build­ing in­su­late the room from out­side noise and vi­bra­tions.

The con­vo­lu­tion of melamine foam wedges is con­fig­ured to ab­sorb sounds that orig­i­nate within the room – like notes from Tay­lor’s flute – and pre­vent them from re­ver­ber­at­ing or echo­ing.

That’s why it’s called an ane­choic cham­ber, Pi­ac­sek ex­plained.

Stripped of the rich res­o­nance cre­ated as melodies carom around a con­cert hall, the re­sult is a dry sound that doesn’t ap­peal to mu­sic-lovers but is per­fect for sci­en­tific anal­y­sis.

“If you’re try­ing to study some­thing that’s mak­ing a sound, like a vi­o­lin or a flute, you don’t want sounds bounc­ing off the walls that will in­ter­fere with your mea­sure­ments,” Pi­ac­sek said.

CWU’s ane­choic cham­ber, part of a new science build­ing that opened last fall, isn’t the first in Wash­ing­ton – and cer­tainly isn’t the big­gest or the best.

Boe­ing analy­ses air­craft noise in a fa­cil­ity the size of a hangar.

Mi­crosoft has three ane­choic cham­bers where en­gi­neers fine-tune speak­ers on tablet com­put­ers and speech pat­terns of on­line as­sis­tants like Cor­tana. The com­pany’s most ad­vanced cham­ber re­cently cap­tured the Guin­ness record as the world’s qui­etest room.

But CWU’s more mod­est fa­cil­ity is the only one at an aca­demic in­sti­tu­tion in Wash­ing­ton, which means it’s open to re­searchers across the North­west.

“I’m hop­ing our fa­cil­ity can be a re­gional re­source, es­pe­cially for peo­ple in­ter­ested in mu­si­cal acous­tics – and it’s al­ready start­ing to hap­pen,” said Pi­ac­sek.

Though the CWU fa­cil­ity has only been op­er­a­tional for a few months, re­searchers from the Univer­sity of Wash­ing­ton and the Univer­sity of Puget Sound have used it for projects as di­verse as anal­y­sis of trum­pets to de­vel­op­ment of a mil­i­tary sound-track­ing de­vice.

Pi­ac­sek, who plays piano and dab­bles in vi­o­lin, plans to use the cham­ber to tackle some com­mon be­liefs among mu­si­cians – such as the con­tention that a vi­o­lin that’s been “bro­ken in” through me­chan­i­cal shak­ing sounds bet­ter than a new in­stru­ment.

Rand Wor­land, who teaches physics at UPS in Ta­coma, ran sound tests in the ane­choic cham­ber to in­ves­ti­gate the way the shape of a trum­pet’s bell af­fects the sound it pro­duces.

One of his stu­dents wants to com­pare dif­fer­ent tech­niques for mut­ing or damp­en­ing drums, while an­other is keen to ex­plore the plunger mutes used to cre­ate a wah-wah ef­fect in trum­pets and trom­bones.

“This is a pretty un­usual fa­cil­ity for a place like CWU,” Wor­land said. “I don’t know of any­where else in the North­west that I could get ac­cess to one.”

Peter Dahl and David Dall’Osto of the UW’s Ap­plied Physics Lab used the ane­choic cham­ber to tackle a mil­i­tary prob­lem: de­vel­op­ment of a sen­si­tive, in­ex­pen­sive in­stru­ment that pin­points the di­rec­tion from which a sound – like gun­shots or the roar of a plane – orig­i­nates by de­tect­ing dis­tur­bances in air mol­e­cules kicked up by pass­ing acous­tic waves.

Sci­en­tists at In­tel­lec­tual Ven­tures (IV), a Belle­vue-based lab cre­ated by for­mer Mi­crosoft tech guru Nathan Myhrvold, have even more far-out con­cepts un­der con­sid­er­a­tion.

Tech­nolo­gies like sonar for track­ing sub­marines and ul­tra­sound imag­ing for medicine har­ness acous­tic en­ergy, but it should be pos­si­ble to boost their ef­fec­tive­ness and cre­ate en­tirely new tools through de­vel­op­ment of ma­te­ri­als that bend and re­fract sound waves in unique ways, said IV’s Yaroslav Urzhu­mov.

Among the ap­pli­ca­tions IV is ex­plor­ing for th­ese so-called meta­ma­te­ri­als is the cre­ation of fo­cused beams of ul­tra­sound or acous­tic en­ergy.

Con­cen­trated sound waves can ex­ert a phys­i­cal force, so beams might be able to dis­rupt the ro­tors of drones or pos­si­bly even blow up dis­tant ob­jects, in the same way med­i­cal ul­tra­sound is used to dis­in­te­grate kid­ney stones, Urzhu­mov said.

He’s ea­ger to test some of the ideas at CWU. “It’s a nat­u­ral, sym­bi­otic path, where a univer­sity can help you fig­ure out how doable some­thing is, while we are work­ing on how to com­mer­cialise things,” he said.

The ane­choic cham­ber, which is the cen­ter piece of CWU’s new, US$1.4mil (RM6mil) acous­tics lab, is also a great place for stu­dents to get hands-on ex­pe­ri­ence with re­search, Pi­ac­sek said.

Tay­lor, the flute player, con­ducted ex­per­i­ments to see if strap-on metal plates, mar­keted as a way to im­prove the tone of wood­wind in­stru­ments, re­ally work. She didn’t see much ef­fect, but ad­mits there might have been some vari­ables she wasn’t able to con­trol for.

Trom­bone player Jace Row­land played his in­stru­ment at var­i­ous an­gles rel­a­tive to a mi­cro­phone to see how di­rec­tion­al­ity af­fects what the au­di­ence hears.

Like Tay­lor, he doesn’t like to hear him­self play in the cham­ber. “The sound feels like it dies even be­fore it leaves the horn,” he said.

But just be­ing in the room doesn’t freak him out, the way it does some peo­ple.

When Pi­ac­sek took his whole class into the cham­ber, one stu­dent couldn’t stand it and had to leave.

The di­rec­tor of Or­field Lab­o­ra­to­ries in Minneapolis, whose ane­choic cham­ber held the record as the world’s qui­etest room be­fore Mi­crosoft, told a Bri­tish re­porter that the long­est any­one has ever been able to en­dure the si­lence was 45 min­utes.

Pi­ac­sek said it’s not the si­lence it­self that strikes peo­ple most, but the queer lack of re­ver­ber­a­tion.

Some vis­i­tors say it feels like their ears are stopped up, be­cause they hear so much less noise than usual.

To Dahl, the UW re­searcher, be­ing in the cham­ber was rem­i­nis­cent of be­ing in a for­est blan­keted with snow. “It’s very stun­ning,” he said.

Pi­ac­sek and other sci­en­tists are scep­ti­cal of sto­ries about peo­ple hal­lu­ci­nat­ing in ane­choic cham­bers – and the sup­posed 45-minute record.

Stephen Tufte, of Lewis & Clark Col­lege in Ore­gon, plans to use the CWU cham­ber to in­ves­ti­gate the acous­tics of the man­dolin – and per­haps see if he can ex­tend the en­durance limit.

“I bet I can break that record,” he said.

The cham­ber’s sound-ab­sorb­ing wedges are re­flected in the trom­bone.

— Pho­tos: TNS

The spe­cial sound cham­ber at Cen­tral Wash­ing­ton is sur­rounded by foam wedges that give it an in­tense quiet.

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