It’s been 11 years since Underworld unleashed classic dance anthem “Born Slippy”. Eleven… years. Of course, if you really want to talk age, you should probably discuss it with Karl Hyde. Hyde, one half of Underworld, is 50 years old. Fifty? It sounds almost Jagger-esque. The idea that dance music could have elder statesmen, that members of the first great wave of dance are at home curling their toes in slippers (some, doubtless, still trying to clear the chemical haze from their brains), boggles the mind.

But then, Karl Hyde is not intent on slipping into the comfy chair just yet. Instead, he’s donning a sparkly, silver-sequined jacket and jumping giddily on stage in Central Park. We’ll come back to the jacket later — but first, the band, the music…

It’s easy to suspect that Underworld might have lost their sense of place in recent years, their sense of where they fit within the music firmament.

The duo, Hyde and Rick Smith, have given themselves solely to producing work; they leave it others to sort through, to evaluate, and sometimes even to locate.

Their most recent studio release, The Riverrun Project, was an online exclusive, and in the past couple of years they’ve also quietly contributed two film soundtracks (Anthony Minghella’s Breaking and Entering and Danny Boyle’s Sunshine), the influence of which can be felt on their upcoming album, Oblivion with Bells. Certainly “To Heal” sounds like nothing else the band has previously released, and it almost surely must be an outtake from one of the film scores — either that, or it’s on loan from Moby.

In support of the new album, Underworld is touring the United States for the first time in five years. Last time, they made a mockery of the idea that a worthwhile electronic-based live show represents a basic contradiction in terms. For a period of two or three years during the mid-to-late ’90s, their performances — largely unscripted and improvised — were as fierce and powerful as those of any artist in any genre you care to mention.

Their live DVD, Everything, Everything, defied conventional wisdom still further.

And now? As evinced by this recent show at Central Park’s Summerstage, Underworld remain admirable in their willingness to please. And yet, the moments of pure invention, of unbridled inspiration, have diminished. It may be unrealistic to expect any band to constantly re-imagine their concert performance, but for the first time, their set conveyed a sense that this was a band hitting the road in support of a new album, rather than playing for the simple joy of playing. Gone was the thrill of the new, replaced by the familiar, the somewhat perfunctory — which may go some way to explain why most of the highlights from this show were to be found in the newer material.

This isn’t entirely as you’d expect, even if it bodes well for the new album.

Since 1988’s Beaucoup Fish, Underworld’s output has delighted and disappointed in frustratingly equal measure. With that in mind, I’d recommend tempering early enthusiasm for the new work with a measure of caution. Oblivion with Bells has much to recommend it — Underworld are too smart, too voracious in their interests to make a wholly dull record — but, as with Riverrun, it’s an uneven batch.

Each of the newer tracks Smith and Hyde elected to play at Summerstage drew from the darker edge of the spectrum, which may say something about the times we live in. After opener “Luetin”, from 2002’s A Hundred Days Off, the night’s second track, “Crocodile”, featured decidedly uplifting vocal harmonies, yet was anchored by a deep, guttural reverberating bass — one meant to provide a tension inside the sweetness.

Likewise, the new album’s stand-out track, “Beautiful Burnout”, was both lovely and full of heavy menace, built around a descending bass line and Karl Hyde’s anaesthetized, heavily treated vocal line, intoning… what exactly? Well, with Underworld there’s always a mystery as to the ‘what,’ isn’t there?

More problematic and unsatisfying, though, were the tracks that for many years have formed the backbone of Underworld’s live show — “Pearl’s Girl”, “REZ/Cowgirl”, and “Born Slippy”. “Pearl’s Girl” began promisingly enough, but Hyde sounded like he was singing over a backing track — which is essentially what he was doing, of course. Having seen Underworld a number of times, I have to say that this was the first I’d ever felt such awareness.

Each of these songs seemed saddled with pitch and tempo problems, not to mention a distinct separation between live voices and backing tracks. While it may just be that the band haven’t toured in a number of years, and that this was one of the first shows of the tour, the results were flat and disappointing.

More troubling is the idea that because dance music draws so strongly on emotion — often aiming to inspire something like euphoria along with an irrepressible urge to move — it could be that, for now at least, the classics in the Underworld canon need to be put away.

Many of the more specifically ‘dance’-oriented numbers had about them the disagreeable whiff of nostalgia. While Hyde and Smith may be giving the crowd what they want, perhaps they aren’t offering what will serve everyone best in the long run. Certainly if this version of the fabled “REZ/Cowgirl” mix is anything to go by, they’ve become bored by it themselves.

Which brings me back to Karl Hyde’s jacket.

Because of the way electronic music is played (essentially, from behind a bank of computers), those dance artists who’ve gained any kind of live reputation have done so foremost by the sheer power of their music, but also by navigating visual interest away from themselves.

In the case of Underworld, the visual fireworks have typically emanated from allusive images and words projected on a large screen. This is why, in Everything, Everything, you never see Karl Hyde in anything more flamboyant than a t-shirt and jeans.

But in the Park, Hyde’s silver jacket — worn over the familiar t-shirt and jeans — bespoke an empty theatricality, a wisecrack devoid of wit or weight. As such, it appeared faintly desperate, or, at best, ill-considered. Perhaps, though, the jacket’s gaudy brightness goes some way to explain the number of people in the crowd who felt compelled to wear sunglasses to an evening show? Certainly by the following afternoon I was prepared to consider the possibility.