Voice. Most powerful and natural instrument.

Friends of my parents were opera singers. She was soprano while he was bass/baritone. I heard her practicing ones in the room and it was unbearably loud. It sounded like regular opera voice 5x louder. I've never heard him singing but when he coughed once next to me it was like an explosion.

In Indian classical music voices sound like instruments almost like imitating them. It is the other way around - instruments imitate perfection of voices.

Learsfool,

Trained human voice can get up to 124dB and in opera often does (recording eng of MET says 120dB: http://www.metoperafamily.org/guild/diva/question.aspx?id=15).

Shouting Guinness Record is 128dB.

Not many instruments can do that. Loudest string instrument is the smallest one - violin=86dB
French Horn (do you play it?) goes up to 114dB while trumpet might go around 140dB because sound is very concentrated. Drum set is about 115dB.

124dB that opera singer can produce is on the threshold of pain. Opera singers have sung with an orchestra without microphones. Many damaged their own hearing (150dB inside of the head). Pain threshold and loss of hearing was probably the reason why they haven't been trained for even louder voice - today we have microphones.

Learsfool,

That's true, voice cannot sustain peak loudness for a long time but rating of over 120dB is more than peak of your French Horn (114dB). As I said before, I witnessed soprano practicing scales in small room and it was scary loud. It wasn't just very loud human voice but rather sounded like painfully loud amplified voice. I just could not believe that the same person can at one time speak regular voice and the other time produce this incredible loudness, and it was only practice and not even peak.

Talking about effort required - how hard it is to play/blow French Horn. Trumpet players often get very red on the face or end up getting big overinflated cheeks (Dizzy Gillespie comes to mind). If I remember correctly, there is more than one French Horn in the orchestra (possibly 2) and they are located in the very back left side to the left of percussion. That placement would suggest that they posses very loud sound.

Learsfool - Very interesting, Thank you.