I think listening to U2 and the Beatles and trying to hear the differences is an excellent introduction to the next part of Hume's essay where he talks about the complexities of aesthetic judgment. Again, my comments follow in green.
The best kinds of music, as with all art, can be very subtle indeed and the right appreciation of them depends on learning to listen with attention and clarity. Any conclusion about the quality of a piece must follow an understanding of just what it is you are listening to. There may be things you need to know about how this kind of music tends to be put together (fugue, for example), or about the harmonic structures of the period. Then you need to be of a focused state of mind, without distractions. If only there were an easily accessible place on the web where one could find on-going suggestions of how to approach particular pieces of music... Oh, wait! Also, let me call attention to the brilliance of Hume's writing. He has to be read carefully, but what a wonderful prose stylist! I think he is also perhaps suggesting that listening to Bach on your iPod, while jostling along on a NY subway train may not be the best approach--that would constitute an "exterior hindrance"!
Here, I am gratified to point out, Hume is calling attention to what I have called the 'time quotient' of music (I even mentioned the example of Homer); the process by which, with the passage of time, the lesser pieces tend to fall by the wayside. How clearly and succinctly he explains phenomena such as Bach: at his death an obscure Saxon organist, but now, 250 years later, admired nearly everywhere. What Hume says about envy and jealousy is sadly true. Unless you are agent looking to make a buck off someone's career, it is not likely you are going to say anything nice about a performer, especially if they are represented by another agent. Singers are notorious for their hatred of other singers and few composers have anything nice to say about other composers. But fifty, a hundred years later, all that is left is the music. It is safe to say that the music of Bach has been beloved of more people every year since his death.
The color analogy is a pretty good one. Hume is making the point here that even though beauty is in the eye and ear of the beholder, still there is a kind of general similarity in the way these organs work. Colorblindness aside, if two people with normal vision are looking at the same color, they see the same color. To take a musical example, we can perhaps find an even better analogy. Take two people with normal functioning ears. With some ear training one might be able to identify intervals the other not. In other words, some people have a natural inclination to hear things musically, and others less so. With musical training you can hear the difference between a fourth and a fifth, easily know what meter the music is in (1234) and perhaps even write down the melody. All these skills certainly add to one's powers of discernment.
I think I know what Hume is talking about here, but from many years teaching music students, I am tempted to put it differently. Isn't what he is talking about what we often call 'talent'? What is ordinarily called talent is usually the result of some natural inclination, many years of hard work and a bit of inspired guidance. Hume here is talking about the natural inclination part, I believe. The "defects in the internal organs" are what people call being tone-deaf. I have had adult beginners come to me and apologize for being 'tone-deaf' when they merely lack any training in how to hear. But some people do indeed have difficulty appreciating the pleasures of music due to a deficiency in listening. I'm not talking about anything physically wrong with the organs of hearing, just the brain's ability to sort out the data. What is it that I am hearing? I have a little anecdote to share: my first audition for music school was a very odd one. I had been in the music education program for a year, but for that, there was no audition. Music education majors do not receive private lessons on their instrument so they don't have to do the traditional audition which consists of going into a room with your instrument and performing in front of one or two professors of music. Egad! People prepare for that for years! I, having recently come from a rock background, had no idea of these things. In fact, the day I was supposed to do my audition because I was switching from music ed to being a real music major I didn't really know what was on the agenda and hadn't even brought my guitar. The music professor just gave me this frustrated look, dragged me into a practice room, played a low note on the piano said "sing it back", played a high note on the piano, said "sing it back", played an interval, major third or something, said "sing it back" and maybe played a minor chord and said "what kind of chord is this?" That was it. If I could do that, they could teach me the rest. Actually, I taught myself most of the rest. Still am. But you get my point? A professor of music can do a rough evaluation of your ability to learn music in about one minute with a piano. Or a zither, for that matter. You just have to know what to look for.
Hume has his own anecdote about the leathern thong and the key in the barrel of wine--an excellent analogy. Let me recount a couple of more from music. I was both an undergraduate and graduate student at McGill University in Montreal and was often impressed with the "delicacy of taste" or what we might call the "precision of perception" of the faculty. I took a graduate seminar in the Shostakovich symphonies and was whistling a theme from one of them as I went into the photocopy room one day. Standing there was a theory professor who immediately said "Shostakovich 5". At the end of that course, by the way, there was a little listening exam where we had to identify not only what symphony a theme came from, but the movement and, if possible, what part of the movement: development, recapitulation? Another time I was taking a course in paleography where you study how music was written before modern notation. Again I was in the photocopy room, this time with a volume from the collected works of Guillaume de Machaut (1300 - 1377). Another theory professor was at the next machine. He glanced over and immediately said, "Machaut". There was nothing on the page to indicate the composer: no text, just the page number. I looked at him with puzzlement and he said, "when I was studying Machaut at Columbia, I spent a lot of time with the collected works and I know the typeface!" This kind of 'delicacy of taste' was not so unusual. A fellow graduate student that I shared an office with was so knowledgeable about Haydn symphonies that he would dash off themes from them on the piano at the drop of a hat. There are one hundred and six Haydn symphonies, by the way.
Now here is a paragraph that we may indeed find puzzling because it hardly seems that in our present world we so universally acknowledge a "delicate taste of wit or beauty". But this is one of the rewards of reading someone like Hume, who comes from quite a different situation than our own. If the "uniform consent and experience" of his age was in favor of a "delicate taste", then this is good to know. The narcissism of our age seems to scarcely know that such a thing is even possible, let alone desirable! Apparently the only thing we acknowledge as universal is the unique individuality of every special snowflake that is the individual consumer of music. And every special snowflake is listening to, uh, Rihanna!?!
This could hardly be said any more clearly! I have often thought that a good practice for the premiere of a new work would be to play it twice in the same concert: once at the beginning and once at the end so the experience of the audience could become more "exact and nice" the second time. Possible for short works, if not for longer ones.
So much of the music today seems to be intended to take advantage of the "flurry or hurry of thought" and combined with the most distracting videos it is possible to conceive, it seems almost that we are trying to avoid even the possibility of judgement. This is probably an unintended consequence of the commercialization of music. In pop music you want an instant hit. If it takes a few listenings with "attention and deliberation" then forget it! There is indeed a species of beauty which is "florid and superficial" and that is precisely what a lot of pop music is intended to be. I'm sure that in all places and times in the history of music there have been artists that specialized in dressing up in colorful costumes and leaping and cavorting about on stage to the accompaniment of loud pounding on a drum. But I'm pretty sure that they were never before paid so highly as they are today, nor given so much prestige. Did Louis XIV attend private fundraisers with his court jesters?
We are still not at the end of Mr. Hume's little essay, but I think I have kicked around Jay-Z enough for today and perhaps bored you, the reader sufficiently as well. Let's end with a Haydn symphony, just to clear the palate: