Single line or multi line?

[breakup]

I've been thinking about this for awhile and I have been wondering which is considered to be more difficult, or is there no difference. On the Piano I play both hands and multiple lines of harmony, along with the melody. On the trumpet I am only playing one line of music whether it be melody or harmony. Is one considered to be more difficult musically, or is each difficult in it's own right. I am aware that string instruments like the violin do occasionally play 2 lines together, and organs and other keyboard and similar instruments play multiple lines at the same time.

[vaniii]

Difficulty is relative.

Each instrument has its own hurdle to overcome to achieve success.

Musically speaking, if you can play your instrument - techincal security, every action at your fingers - realising notes on the page is second nature.  Idiomacy dictates how one plays there instrument; a piano is played with two hands, melody accompaniment, chords or counterpoint.  Melody instruments have their own technical challenges,  generally speaking tonal awareness and tuning.

When talking about individual notes or notes played together simultaneously, we are not talking about music, and still trying to overcome the first techincal hurdles, namely recognition and facility.

[outin]

While it's relative it's also personal. I find piano playing (even at the beginner level really) the most difficult of all the musical activities I have done and that's mostly because of the high level of physical and cognitive multitasking required. Those have never been my strengths. My strengths were always more in hearing and keeping tune and rhythm, which is why I find singing and playing the flute so much easier. Guitar is somewhere in the middle, still a lot easier than piano.

[keypeg]

I think that comparing any instrument to another in terms of which is "harder" is going in the wrong direction.  Each instrument has its own challenges.  One element of piano playing that is highlighted by the OP is the fact that you play many notes at the same time.  Getting reading skills is more critical in this instrument, knowing how to balance out different voices, and getting a handle on different rhythms of different sections (such as 2 against 3) - these are all challenges brought about by this first factor of "all those notes played at the same time".  Piano is also a more "mechanical" instrument with less direct access to the parts that make the music.  There is a whole machinery between you and the vibrating strings.  This makes it "easier" to produce "a" sound - cats and babies can do that - but not necessarily to produce a musical sound.

I play some other instruments which were self-taught: various recorders, classical guitar, singing.  I started violin as an adult, and it's the first instrument for which I had lessons.  I broke off after a few years due to a bunch of things, and am relearning it right now.  So I'll write about that.

The challenges on violin are different.  You have to work hard even to produce a decent quality of sound when you start off, while a small child can push down on a piano key and you'll get a robust note.  You're trying to get your bow to track straight while the natural motion of the arm would make it form an arc like your car's windshield wiper.  You can't even think of music yet.  Meanwhile you need to find precise notes on a smooth stretch of string - 4 of them - with no markers. No black and white keys here!  You will also find one and the same note on a different string, in a different location.  That D4 is one broad piano key and only there, and you can land anywhere on that key. On violin, even if you land in the right spot, if you angle a few millimeters to the left or right, bang, you're out of tune.

Like with piano you have to coordinate your two hands.  Only here each hand as a different task - the left finds the note, the right finds the quality of the note.  If your bow changes direction or strings and if it is not timed right with your other hand finding the note, you'll get strange hiccups and extra notes.  So you've got coordination here too.  At a more advanced level you get into subtlety of musical sound.  A single note, say sforzando, can start in a burst and continue quietly, it can fade away, or swell - which gives you endless possibilities but also the need for the skills to produce it.  The piano note, once you strike it, just continues and gradually fades.

A more interesting question might be What advantages are there to playing more than one instrument - What can each of two instruments "give" to the other?  When you play a bowed string instrument or wind instrument, you get a feel for the singing line.  That may be an advantage for getting that singing line into piano, which is percussive.  While you are working for all the rich textures that you can produce with a bow, it might inspire you to explore what you can do with piano.  Otoh, piano makes you acutely aware of rhythm and timing, and you'll end up bringing that into your wind or string instrument.  And piano may hone your ear for pitches - though the temperament to which pianos are tuned can also be a negative thing.

Just as some thoughts thrown out on a Friday morning.