φθόγγος denotes articulate sound—whether of human voice, musical instruments, or even nature. Unlike inarticulate noise, it refers to clear, distinct sounds that can be perceived and recognized. Paul uses it twice rhetorically: in Romans 10:18, quoting Psalm 19, he speaks of the gospel's universal reach using the language of creation's φθόγγος going out to all the earth. In 1 Corinthians 14:7, he illustrates the necessity of intelligible speech in worship by comparing tongue-speaking to musical instruments—a flute or harp producing unclear φθόγγοι would be useless for communication.