Welcome to Brain Stuff, a production of iHeartRadio.

Hey, Brain Stuff, Lauren Volgobom here.

When you, a human, want to audibly communicate with another human, you generally use your

voice.

A speech happens when air passes through your larynx or voice box, and is added to noises

made with your throat, nasal passages, sinuses, and mouth.

This is a great way to communicate, but there are some drawbacks.

Of course, there are people who have trouble making those noises or hearing them due to

any number of conditions.

But that aside, let's take the particular instance of your living on a mountain side,

and a friend living one slope over.

Just shouting to each other isn't always that effective.

But for one thing, shouting creates a lot of echoes among them nooks and crannies of

mountain slopes, and the average outdoor range of an intelligible human voice is only about

590 feet or 180 meters under normal conditions.

A short of walking over to where your friend lives to carry on a conversation at a reasonable

speaking distance, or communicating with some sort of visual technique, your next best

bet is to whistle.

A whistling is the product of air being forced through a small hole made by your lips.

A whistle is different from your voice, because it's clear, and the frequency is narrow and

high pitched.

The sound of a whistle can carry for more than five miles or eight kilometers, and it holds

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