The sentence you provided has some minor grammatical issues and could be made clearer. Here's a revised version: "The farther away the solid obstruction is, the longer it takes for the echo to return." The sentence you provided has some minor grammatical issues and could be made clearer. Here's a revised version: "The farther away the solid obstruction is, the longer it takes for the echo to return." This version is more grammatically correct and conveys the same meaning.