It all looks and sounds great, but the clock is ticking — therapy! — and we are no closer to understanding the real Neil. Until, at long last, the older singer cracks and stops obfuscating. Naturally, the source of his discontent can be found in his childhood, and the show finally makes the essential connection between Diamond’s artistry and his roots, including his Jewishness. By that point it feels rushed and not quite earned, not to mention a little too nakedly sentimental. And yet, the beating heart of “A Beautiful Noise” is that sequence, featuring “Brooklyn Roads” and “America” leading into “Shilo,” which becomes Diamond’s Rosebud and is performed with almost unbearable grace by the ensemble member Jordan Dobson. Never mind: naked sentimentality is just fine.