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floor a few feet from a wall has a hol-

low quality because of slight echoes

that immediately follow the original

click of contact. The echoes from

the stick tapping the floor follow

too quickly to distinguish as distinct

replicas of the original click, but they

add slightly to the original click sound

nonetheless.

If you tap the stick closer to the

wall (within a few inches), the click

will have a somewhat higher pitch.

Some people report that clicks right

next to the wall sound “deader” be-

cause they contain fewer echoes and

overtones.

4

See Behind You

Sound shadowing is a close

cousin of echolocation. It lets

you sense when someone—or a large

something, such as a predator—is right

behind you, even when that someone

(or something) makes no sound.

Stand with your eyes closed on a

carpeted surface (or another sound-

deadening surface, such as grass or

beach sand), and have a friend sneak

up behind you so that you don’t

hear his or her footsteps, breath-

ing, or clothes rustling. The experi-

ment works best when you have a

psychologytoday.com (june 2018), copyright © 2018

by eric haseltine.

conspicuous sound source, such as a

radio, located about ten feet behind

you to create background noise.

As your friend approaches from

behind, even though you can’t see or

hear him or her directly, you should

be able to “feel” the person’s proxim-

ity by the sound shadow that he or

she casts—the way the person blocks

the sound. If you pay close attention

to the sound shadow, you’ll perceive

it has two parts: a slight lowering of

volume and a deadening of echoes

of the radio noise off surfaces be-

hind you. These two effects become

increasingly obvious as the person

gets closer to you. Our unconscious

ability to sense that someone is be-

hind us may have given rise to that

overworked phrase in thrillers and

mysteries: “She felt someone watch-

ing her.”

Although the perception of sound

shadows, like echolocation, is yet an-

other example of implicit memory, it

may also have a hardwired survival

component that helps us fill in a large

blind spot behind us that predatory

animals (and nasty humans) could

otherwise exploit.

Mazel Tov!

I’d like to think that halfway through Nicole Kidman’s

last name, there’s a tiny bar mitzvah.

@justinshanes

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