Obvious; when something is "in-your-face" and apparent.
"I hear you, LOUD AND CLEAR!"
Your directions were loud and clear.
Clearly audible and understood. More radio slang. Also an answer to the question "Do you copy?"
"Holy fucking shit Houston, are you reading me, over?"
"Loud and clear, over"
Used in radio communications to report that the communications link is working properly.
Station Bravo: Station Alpha, how do you hear me, over?
Station Alpha: Station Bravo, I hear you loud and clear, over and out.
Affirmative. Originally used over the radio to signify that you heard the other - you guessed it - 'loud and clear', the term now simply means "Yes, I understand you, now kindly leave me alone."
Teacher: "By Lord Iain, I want that damned work in tomorrow or it's your head! Do you hear me?"
Iain: "Loud and clear."