Listen to This, By Alex Ross

Is there another music critic writing today who could change key within an essay from John Dowland to Led Zeppelin (specifically, "Dazed and Confused"), JS Bach to Robert Johnson, without fluffing the notes or tumbling into an ear-splitting dissonance? Alex Ross of the New Yorker can span endless octaves of period and genre without the slightest sign of strain. Those particular leaps between Renaissance dance and song, and the pillars of hard rock, come in a bravura piece on the chaconne and its offshoot the lamento: a descending bass line "like a chilly staircase stretching out before one's feet". Such strands of musical DNA migrate from epoch to epoch, culture to culture. They crop up as foundation and inspiration with a fertility that makes a nonsense of moribund divisions between the "pop" and "classical" traditions.

That vision of music and its makers as a single realm artificially split into warring camps drove Ross's superb book about the sound of the 20th century, The Rest is Noise. Here he selects and adapts from more than a dozen years of New Yorker pieces. An initial manifesto voices with blazing eloquence his impatience with the class-bound fate of classical music in the West, "an ageless diva on a nonstop farewell tour". Later he quotes, in sympathy, Juilliard School drop-out Miles Davis's belief that "No white symphony orchestra was going to hire a little black motherfucker like me". Instead, Ross imagines a future in which hard-core punks will hear Beethoven's Eroica and discover, as he did, the shock of the new in its convention-wrecking 200-year-old chords.

The book splits its attention, more or less equally, between the living and the dead. Lavish New Yorker funding permits expansive on-the-road profiles of Radiohead, Bob Dylan and Björk. He tracks the latter from Iceland to London to Brazil, and basks in the glow of "original bliss" in her eclectic soundscapes. The elfin spellbinder's all-encompassing taste segues from Stockhausen to Justin Timberlake: pretty much his ideal for a kind of transcendental fusion.

With conductor-composer Esa-Pekka Salonen in Los Angeles, and pianist-teacher Mitsuko Uchida in Vermont, Ross enjoys the company of forward-thinking virtuosi from the classical side of the fence who seek to escape their music's entanglement in "a web of money and status". After his podium debut in LA, Salonen slopes off to a club and gets talking to a woman at the bar. What had he been doing that night, she asks? "Well, I just conducted the LA Philharmonic". "That's the dumbest line I ever heard".

His employer's generosity means that Ross spends perhaps too much time hanging out with favourite stars. The threat of fan-boy gush looms. "Like all greatly gifted people," Thom Yorke of Radiohead "is not always easy to be around"; Uchida has "a wildly oscillating laugh that sounds like a flock of songbirds ready to be transcribed by Olivier Messiaen". Yet when he listens to the music rather than the fame, his evocations sound pitch-perfect. The voice in early Björk burns "like candles in a dark room"; Schubert's Winterreise song cycle shares a "skeletal lyricism" with Samuel Beckett.

Ross communes, in a learned but ever preachy mode, with giants of the past. Fluent overviews of Mozart, Verdi, Schubert and Brahms may not break much new ground. Still, the devotee of Kid A, Vespertine or Love and Theft who enjoys this book should rush to listen without prejudice (Ross takes care to remind us that Mozart wrote a canon for six voices entitled Leck mich im Arsch: K.231/382c). His buff of the future shuffles on an iPod through the entire evolution of recorded sound, as past and present meet. Dylan, caught performing at a folksy farmers' fair in Washington state, foreshadows this musical utopia: both fathomless genius and jobbing minstrel, "historical enough to be the subject of university seminars, yet he wanders the land playing to tipsy crowds".

Ross ends not with a living legend but a heartfelt portrait of Johannes Brahms: the ultimate example of a composer – "one troubled mind commiserating with another" – scorned by the young but often adored once time begins to leave its mark. For Ross, the first Intermezzo Opus 117 – a simple, aching folk-song setting for piano – is "the music you will hear when you die". For me, it might just be the Alto Rhapsody, sung by Kathleen Ferrier with Clemens Krauss and the LPO in 1947. "Blessed are the sad" indeed – and blessed is the critic who, like Ross, can stride so nimbly over the keyboard of time and style without losing his ear for the feeling behind the form.