So let's make a list of the things I just mentioned:
- Tuning: a lot of pop music now uses Auto-tune, which corrects imperfections in the tuning of the voice. If a note is a bit flat, it brings it up to pitch and vice versa. Here is a famous example:
What gives this its distinctive sound is the over-use of Auto-tune. You can hear the voice jumping from pitch to pitch as if it were a synthesizer. Other places, the Auto-tune was not used because you can hear Cher sliding from one note to another. A really good singer has enough technique to not need Auto-tune, but a lot of singers in pop music do not have much technique. Try to imagine Bob Dylan using Auto-tune! He sure wouldn't sound like Dylan anymore. He has made a virtue out of the imperfections of the singing voice. For him, singing out of tune is part of the expression. As a matter of fact, it can be that for every singer, even classical ones, because one of the great virtues of the voice is that it can sing slightly sharp or slightly flat--which is expressive!
- Breath control: a lot of singing is about breathing. How long can you hold a note? Can you hold a note without wavering or wobbling? In much pop music notes are not held for very long. Listen to Dylan singing "Like a Rolling Stone". At the beginning the only note held for any length of time is the "you" of "didn't you" and the pitch wobbles alarmingly. Compare this to Cher's singing. Dylan tends to spit out small groups of words in clumps, Cher holds every note out.
- Timbre is the slightly fancy musical word for tone-color. In pop music a lot of impurities are actively cultivated for their expressive qualities. Céline Dion cultivates a fairly pure voice as do most of the pop divas. Bob Dylan, in common with singers like Tom Waits and Leonard Cohen, cultivates a gravelly or reedy tone full of impurities. This supposedly adds 'authenticity'. Here is a little Tom Waits as an example. One of the oddest things I ever saw on YouTube was a German baritone, an opera singer, doing a Tom Waits song! Of course it was better than if Tom Waits tried to do an opera aria, but still...
- Phrasing is a huge and difficult to discuss topic, but I might be able to find some examples. I recall reading a book on phrasing once that turned out to be of little value because this is one of those times where written notation isn't much help. You really need to hear phrasing! Actually, a really good example is "Like a Rolling Stone". Listen to how the words of the verse tumble over one another, leading up to "didn't you" each time. This leading, this pointing forward, is one of the most important things in phrasing.
Let's listen to some Céline Dion. This is "I Surrender" from 2007. She is a terrific singer, without a doubt. As is sometimes said, she has a great instrument (her vocal cords, diaphragm, lungs, the whole physical aspect that produces the sound) which she has also trained to a high degree of perfection. She can do what she wants to do with it. Listen, for example to the phrase towards the beginning that ends with "find a way". On "way" she pushes the pitch up slightly and then slides down as an ornament. No Auto-tune here!
But I find the whole experience disappointing because the song is so bland. It seems full of emotion and expression, but it really isn't. It is too predictable for one thing. Not one harmony is unexpected. The melody, such as it is, is dull and lifeless. Go ahead, sing me the tune. Not easy is it? Because it is so unmemorable. There are no interesting contrasts in the song or the arrangement. It is all one big blanket of sound, pulsing predictably. The fact that Dion is such an excellent singer and the production is so elaborate makes it listenable, but not really enjoyable. That's for me, of course. For most people this would be just the thing because they don't actually want the music to be too interesting. Most people prefer the predictable and comfortable. But predictable, comfortable music has a pretty short shelf-life. In any case, this is perfect for Las Vegas, which is pretty much the most scathing criticism I can deliver!
Now let's hear some more Dylan for contrast. This is the original version of "All Along the Watchtower" that many, many others have since recorded.
Now this has pretty much everything against it: minimal production values, no video, no dancing, the same three chords over and over again--this song has no contrasting section, just the verse over and over. Some of the worst harmonica playing! Plus, Dylan's singing. Every note sounds like it is a strain. Every note he sings is at least a bit out of tune! Guitar, bass and drums, nothing else (but the guitar might be double-tracked as it sounds too full for just a single acoustic guitar). This has nothing going for it! Well, except the song with those amazing words. After all these years I still couldn't tell you what the song is about or what the words mean. But they are very evocative. This is one of those mysteries of music: this song and even this performance is a thousand times more interesting than the song by Céline Dion. It shouldn't be, but it is. A lot of it is that it has a unique sound, unlike any other song, especially when Dylan sings it. But there are a thousand songs like Dion's and they all sound much the same.