In northern Sweden, the word yes is widely communicated by a sound that’s reminiscent of someone sucking through a straw. It’s called the pulmonic ingressive. Linguist Robert Eklund calls this a neglected universal, meaning that it’s only recently been recognized as a sound that’s part of many languages around the world, even though it’s been around for a while. In one study, Swedes talking on the phone used ingressive speech when they thought they were speaking with a human, but not when they thought they were conveying the same information to a computer. This is part of a complete episode.