Do Sounds Bounce?Do Sounds Bounce?

ReflectionReflection

the bouncing of a sound wave off of a surface

NOT ALL of the sound wave reflects off of a surface.

Some of the wave’s energy enters the surface, and part of the sound disappears.

This is called…

ABSORPTION - the disappearance of a sound wave into a surface

THINK ABOUT IT!THINK ABOUT IT!

• Which will reflect more sound, a book or a t-shirt? Which will absorb more sound?

Have you ever heard someone snoring Have you ever heard someone snoring through the walls?through the walls?

Why?Why?

Part of the energy of a sound wave may travel through a surface and

come out the other side

Amount is reflected and absorbed Amount is reflected and absorbed depends on…depends on…

…how hard, smooth, soft or textured an object is.

Hard and smooth –much of the sound is reflected

Soft and textured–less energy reflected–more is absorbed

Can You Solve the Mystery?Can You Solve the Mystery?

Designing concert halls has always been a tricky business. To get the “right” sound engineers try to get a good balance of reflection and absorption. Too much reflection results in an empty, hollow sound. Too much absorption deadens the music.

Can You Solve the Mystery? (cont.)Can You Solve the Mystery? (cont.)Mystery

When the London Music Hall was built in 1871 the hall was considered to be one of the great places in the world to hear music.

Can You Solve the Mystery? (cont.)Can You Solve the Mystery? (cont.)

By the 1930s listeners complained that the music did not sound good anymore. Sound engineers were baffled. Nothing in the concert hall had changed since it was built over 60 years earlier!

Try to come up with a solution!

Hint:Hint:

Typical women’s clothing in the Late 1800s when the London Music Hall was built.

SolutionSolution

The concert hall may have stayed the same, but its audience had changed. Most importantly, women were no longer wearing the billowing, layered sound-absorbing gowns that had been popular earlier. The new styles were shorter and simpler, and didn’t absorb sound as well. Overall they changed the balance of reflection and absorption of the sound in the room.