To describe something as pointless, people may liken it to shouting into the wind. This idiom implies that making noise against the flow of air is very hard. But shouting into the wind isn’t that difficult after all, new research shows.
In fact, sending sounds upwind, against the flow of air, actually makes them louder. So someone standing in front of you should have no problem hearing you. This is due to what’s known as convective amplification.
Sound sent downwind, in contrast, is quieter.
The reason people think it’s hard to shout upwind is simple, explains Ville Pulkki. “When you yell against the wind, you hear yourself worse.” When you yell upwind, your ears are downwind of your mouth. So your own voice sounds quieter to you. Pulkki studies acoustics at Aalto University in Espoo, Finland. He was part of a team that has just investigated the effects of shouting upwind.
Pulkki first tested the effect by hollering with his head out the top of a moving car. The car’s motion made air whip past Pulkki’s face. This mimicked the effect of a strong wind. Pulkki’s head was surrounded by microphones. They recorded the volume of his voice.
The results did not clearly show why yelling upwind seems hard. So, Pulkki and his team upped its technology game.
In the new study, this team put a speaker playing multiple tones on top of a moving vehicle. That speaker mimicked the effect of someone yelling. A cylinder stood in for the yeller’s head. Microphones measured how loud the noise would sound where the mechanical yeller’s mouth and ears would be. These data were collected as the speaker was “yelling” either upwind or downwind.
The experiments — together with computer models — confirmed why someone’s shout sounds quieter to them when they’re facing upwind. The researchers described their findings March 31 in Scientific Reports.
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