Si is just as dependent on sensations as Se. Si savors sensations while Se experiences them in breadth. As an extraverted perception function, Se seeks variety of different sensations.
Ni and Ne are both equally dependent on internal visions. Intuit means to look inward, Introvert means to turn inward, Extrovert (Extravert) means to turn outward. Taken together, Ni savors inspiration internally, Ne seeks variety of inspirations.
Ni tends to have difficulty expressing visions. By stark contrast, Ne is very good at expressing visions and hypnotizing the audience with the charisma of its expression. The main problem with Ne and its visions is that, like its fellow extraverted perception function Se, Ne is merely interested in breadth of the vision. So while Ne is good at expressing visions, it is more content with leaving others with the application of it.
Ni lives the vision internally in what could be described as pure imagination. An Ni is likely less interested in expressing the vision towards the outer world, but merely to proclaim it. An Ni vision is less interested in affecting the outer world, but rather interested in living the internal images in the mind -- walking the inner landscape.
Si is dependent on external objects perceived through the senses, and turned inward. Unlike Se, Si is interested in experiencing sensations in depth and savoring them internally.
Which brings me to Si and its perception of music. Of any function, Si is most in tune with the inner forms of concrete experience. Where Se will likely dance to the music and live the intensity of engaging in physical impulses, Si will passively appreciate the forms and beauty derived from music.
In the case of N and its way of looking at music, Ni will transform the sensory experience of listening to music into an internal flight of fancy. For Ni, music or any other sensory experience is merely the starting off point for an esoteric journey in the imagination. Ne will hear music and look for ways to expand it -- Ne is interested in transforming the outer world through internal insights. Ne will look at the external world and find ways to make it better.