are two heads better than one?

When I was writing my intonation book (English Intonation, CUP 2006), one point that I tried to make clear is that some aspects of intonation are more important than others. This is particularly relevant to EFL learners, who would do best to concentrate on the major issues and ignore, or at least leave till later, various minor ones.
So I organized the book in such a way that — after a brief introductory chapter — one chapter is devoted to each in turn of the “three Ts”: tone (falls, rises, and fall-rises), tonicity (which words do we accent?), and tonality (how do we divide the material up, where do we place boundaries?). The matters I regard as “the less crucial choices” (p. 10) I relegate to chapter five, “Beyond the Three Ts”. Among them are the prenuclear part of the intonation phrase (preheads, different kinds of head), finer analysis of tone (e.g. high fall vs. low fall), non-nuclear accenting, major and minor focus, and a discussion of which function words are (against the general rule) typically accented.

Now I read in David Deterding’s blog an account of a presentation given in China by my colleague Francis Nolan, who made an additional point.

However, it is not so important to imitate the finer distinctions of the intonational tunes of native speakers, partly because there is a huge amount of variation in tone usage in Britain and elsewhere, so listeners are accustomed to hearing substantial differences among the people they talk to. To support this, he played lots of data from speakers from around the UK and Ireland.

I think this is exactly right. Deep down, nearly all native-speaker varieties agree very substantially in the way they use intonation. Superficially, there are considerable differences in the details of pitch movement.

However, a questioner in the audience disagreed, saying that differences in head types must be important, since they are “shown” in my book. David says, rightly,

While [the account of different types of head] is almost certainly an accurate description of the intonational patterns of native speakers of RP British English, there is no way that listeners will misunderstand the message if a non-native speaker uses a rising head rather than a high head. But the questioner was adamant that the distinction is absolutely vital. It is in the book by John Wells, she insisted, so it must be important.

You can see my dilemma. If I hadn’t included the possibility of rising heads in my account, I would have been rightly criticized for lack of completeness. If I had followed the O’Connor and Arnold (1973) model, and presented rising head plus high fall as one of ten apparently equally important tunes — this is their number 6, the “Long Jump” — I would have failed to make the point that the distinction between this pattern and high head plus high fall (their number 2, the “High Drop”) is not actually terribly important.

I have assured David that I agree with him and with Francis. Perhaps in the book I ought to have made my point more clearly, so that all my Chinese readers could grasp it more readily.