How the same music note can sound different?

[duoheer]

Hey guys, I have 2 questions:
1. If you press the loudness pedal on a piano and sing a note, a sound usually comes from the piano, why?
2.With a trombone, a skilled player will produce an attractive sound, whereas an unskilled player will produce an unattractive sound while playing the same note. Why?
Thank guys

 

[Meir Achuz]

1. The loudness pedal removes th hammers from the strings.
When you sing a note, the strings of the same (or close) frequency to your note (or overtones) vibrate in resonance.

2. Attractiveness of the sound is subjective, but it depends on the frequency and distribution of the overtones. This is determined by the interaction of the lip with the mouthpiece, the volume of blowing, and
the placement of the tube. These are all too hard to calculate, but an experienced and talented player with a good ear learns to adjust all effects to create what he hears as pleasing.