To begin with, I had better define collaborative coherency. It is simply the term I use to describe the extent to which lyrics must coordinate themselves with the music they have been paired with. It is an essential but too-often overlooked concept.
There are two levels of collaborative coherency. The first and most basic level, which this article will seek to tackle, is simply a matter of professionalism: matching musical rhythms with natural speaking rhythms and ensuring that emphases supplied by pitch do not disrupt speech—stress coherency. A good example of how not on pain of death to do this is Lady Gaga’s “Telephone:”
The music isn’t bad, but Gaga appears to have given little or no thought as to how much the music disrupts the lyrics. Take the line, “I’m kinda busy.” First, read that sentence out loud, just as you normally would in conversation, particularly the last word. Unless you suffer from a crippling speech impediment, your pronunciation of “busy” will place emphasis on the first syllable and leave the second syllable briskly clipped. But then look at how Gaga sets the word; both syllables are given a rhythmically equivalent setting, contorting the normal emphases of the word into a tortured monorhythm. Given that, a lovely band-aid solution would have been to place the second syllable of the word “busy” on a lower pitch, thus giving it an appropriately subordinate position. However, Gaga uses the same pitch for both notes, leaving the awkward rhythm to fend for itself.
A subtler example comes from the beginning of the same song. First, read out “Hello, hello baby, you called, I can’t hear a thing” as you would in normal conversation, or as normal a conversation as it is possible to have when you are narrating your beaux’s telephone habits. You will tend to place natural pauses between phrases, breaking up the sentence into coherent chunks. Gaga will have no truck with this, opting instead to render the sentence as one continuous string of speech, absent anything resembling a pause. Before, the flaw was merely jarring. Here it turns the entire line into indecipherable gibberish.
As a general rule, the natural rhythms and emphases of the music and the lyrics must be coordinated if they are to be yoked to each other. If you do break collaborative coherency, it must be deliberate and must serve a purpose…but that is interactive coherency—another article for another time.