Voice. Most powerful and natural instrument.

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.

Kijanki is absolutely correct. Issues of perception aside, I will offer this example:

I have sat in the clarinet section of the Metropolitan Opera Orchestra during rehearsals of many operas. It is typical during the sitzprobe (first time that the orchestra rehearses with the singers; usually in the rehearsal room, not in the pit/stage), for the singers to stand behind the orchestra, also facing the conductor. They stand further back than both the horns, and the trumpets/trombones. The sheer volume that a great singer can produce is astounding. It is sometimes unbearable in it's power (undistorted, of course), and can definitely be more powerful than a horn, trumpet, or trombone playing full tilt.

Believe it, or not.

Hi Frogman - as usual, you are correct. Indeed, I have had that experience many times myself with opera. I had been thinking more along the lines of an audience perspective. Even opera voices sometimes have difficulty carrying to the back of the hall, though not of course at the Met, where they have the very highest caliber, and a very well designed hall. However, even the average opera voice is not remotely comparable to the average human voice - the average jazz, folk, or pop singer relying on amplification would be incapable of such amplitude. It takes very well trained voices indeed to reach those volumes. I suppose the sound power of such a voice could indeed exceed that even of a trombone, though I doubt it would approach the bass drum. Unfortunately, my reference only gives the relative sound power of the orchestral instruments, not including the voice.

Kijanki, the very top professional orchestras (perhaps 15 or so in the US) will employ 6 horn players. Many others will employ 5, and almost all will employ 4. A great deal of the orchestral/opera/ballet rep calls for four horn parts. Their location on stage or in the pit varies quite a bit from orchestra to orchestra, but is usually towards the back, often in the very back. It also depends on the space. The placement of the horn section is always an acoustical issue, due to the fact that our bells point "the wrong way."

As far as decibel level compared to the trumpet, the horn is capable of more decibels, but the trumpet's sound power is slightly higher, because of the higher register. That is a good example of how our perception is involved.

As far as how hard is it to blow, it does take considerable physical effort. Learning to use the airstream (involving particularly the muscles of the diaphragm) properly is only part of it, however - there are also the muscles of the lips, which are as highly developed as any set of muscles a professional athlete would use. In general, all musicians are using much weaker muscle groups than athletes, putting just as much stress on them, and they have to last us for much longer careers. Very few brass players make it through their careers without major "chop problems" at some point. Though usually it is just a case of fatigue resulting from overuse, small tears or even nerve damage can result, and these type of injuries can end careers. I have unfortunately had several close friends that this has happened to.

Learsfool - Very interesting, Thank you.

Why wouldn't a vastly more complex instrument with a seamless interface have the edge in overall musicality?

We're close on the interface issue: the kazoo. What we need is a better kazoo.