Two, three and four beats in a bar are pretty standard in music. But what happens when a composer decides to go with 7 or 5 or 13 as the underlying structure? And why would they do that?

Tom Service talks to composer Anna Meredith and conductor Martyn Brabbins about the fascination and challenge of the off-beat beat.

What is it about the tango that has enabled it to transcend its origins in the late 19th-century slums of Buenos Aires to become one of most popular dances in the world's glittering ballrooms and beloved of gymnasts, figure skaters and synchronized swimmers? How did tango escape the sparkle of the glitter ball and the borders of Argentina to be taken seriously as art music?

It may take two to tango but there's a trio here to tease out the complex, multiple strands of this beguiling dance, as Tom Service is joined by tango historian John Turci-Escobar and Buenos Aires-born tango dancer Carla Dominguez.

David Papp (producer)

Tom Service takes on the largest instrument created by human hands: the organ. With the help of organist Anna Lapwood, Tom asks: what makes the organ so mighty? Why has it fascinated musicians from Bach to Procol Harum? Along the way, Tom will delve into the Delphian roots of the organ and we’ll hear what its ancestor the Hydraulis sounded like, created in ancient Egypt. And we’ll drop in on Madison Square Garden where Gladys Gooding entertained huge audiences at sports events for over thirty years, starting in the 1930s. Finally, we’ll hear what makes the organ timeless and immortal in music by John Cage and Olivier Messiaen. All hail: the organ!

Tom Service looks under the bonnet at musical climaxes and crescendos. How do composers negotiate musical drama to often devastating beauty and power?

You might think classical music is timeless and sits above passing trends and fashions, but in this edition of The Listening Service Tom discovers otherwise. He talks to newspaper fashion director Lisa Armstrong about how trends are made in what we wear, and to music streaming curator Guy Jones, about what influences our listening habits.

And – spoiler alert - classical music is IN!

Tom Service dips a toe into the choppy waters of Historically Informed Performance Practice. HIPP is the latest term for the well-established vogue of recreating the sounds of music from past centuries. But how can we possibly know what music sounded like before it was recorded? Can HIPP ever be more than a hopeful stab in the dark? Like quinoa and farmers' markets, is it merely another facet of fashion and commercial imperative, a mirror which reflects us and our current concerns straight back at ourselves? Or is it a revitalising and constantly evolving force for good, sweeping away years of lazy and complacent tradition, revealing afresh music we thought we knew? Violinist Rachel Podger and chronicler of HIPP Nicholas Kenyon are on hand to help.

David Papp (producer)

The classical music canon - who decides what's in and what's out? Can it and should it change?

Bach, Beethoven, Brahms - widely regarded as permanent fixtures in the generally accepted canon. But what about the Chevalier de Saint-Georges, Louise Farrenc or Steve Reich?

Tom Service looks at how and why certain composers and pieces of music became part of an established canon, and how things are changing over time, especially with the desire to see better representation of women and composers from more diverse backgrounds in the mix.

With writer and historian Katy Hamilton and oboist and researcher Uchenna Ngwe.

Tom Service is joined by harpsichordist Richard Egarr to explore one of the most mysterious, complex and rewarding pieces in all music, Bach's keyboard work The Goldberg Variations.

Listening to slow music, composing slow music and playing slow music - what happens when our music goes slow? Tom Service asks if going slow means making a chilled-out, super-relaxed, concentration-free zone or if slow music is more focused, more intense, more dramatic, more emotionally and intellectually compelling than music that goes fast. This week's witnesses helping him find the answers are composer Thomas Adès and novelist AL Kennedy.

How is the rhythm and physicality of our breathing reflected in music? From operatic breath control to circular breathing techniques to a flautist inspired by the relearning of her technique after sinus and asthma problems, Tom looks at a fundamental element of music making.