Are there different ways of listening to a tone?

[earless]

I've always been into music, and often listened attentively to different musical pieces but never received any formal music education. I'm 30 now, and only three years ago I started learning to read notes, playing the piano (by sight) and singing. I can differentiate tones and have no problem singing a melody or tone I heard, but have big difficulties playing a melody by ear on the piano.

One month ago I started with ear training and I am still stuck on comparing minor and major 2nd intervals. Finally (after about 20h of training on this section), I am able to immediately differentiate between these to intervals when the tones are played simultaneously. I can do this now by hearing "the interval" or the total sound of the two notes played together, but I still have a hard time of dividing this sound into two separate notes.

While practicing in mixed mode (ascending and descending 2nd intervals) I noticed, that when the notes are played consecutively I'm often wrong on identifying the higher note. Especially on certain intervals like B-C. Sometimes the B just sounds higher than the C. It feels like it depends on the "aspect" of the tone I pay attention to. I am finally able to concentrate on the "height aspect" of the tone and correctly identify the C as the higher one in 8 out of 10 cases. But when I don't concentrate enough and just do a quick listen, the B sounds higher.

I'm just curious: Does anybody else experience this? Are there any tips what to watch out for?

Thank you very much!