In the beginning was the DJ. Long before rappers took centre stage – both literally and figuratively – in the hip hop music scene, DJs had been instigating nothing short of a musical revolution: not only did they create the musical style that would serve as the foundation for hip hop culture, but they also transformed what had previously just been a playback device into a musical instrument. In Groove Music: The Art and Culture of the Hip Hop DJ, Mark Katz – an Associate Professor at the University of North Carolina at Chapel Hill and ‘aspiring turntablist’ himself – offers an engrossing exploration of hip hop DJ culture: from its brash beginnings, through its controversies and setbacks, to its underground resurgence.

Since the publication of Tricia Rose's Black Noise in Reference Rose1994, hip hop has become firmly established as a subject of academic investigation, where it is often the subject of debates about race, gender and class and their relationship to hip hop ‘authenticity’. Katz addresses these issues in the Introduction to his book, by situating his work in the context of theories of technology, race, ethnicity and gender. He gives a nod to the social construction of technology (SCOT), which ‘holds that technologies do not determine their uses and meanings; rather, these are determined (i.e., constructed) in a social context by the people who invent, design, sell, and use the technologies’ (p. 9). Likewise, he rejects ‘essentialist’ views of identity, and ‘insist[s] on the constructed nature of technology and identity because the idea explicitly recognizes the power that individuals and communities have in determining their identities, values, and aesthetics’ (p. 9). Thus, African Americans aren't born with rhythm, nor are whites born without it; the number of women DJs has less to do with a gendered reluctance to engage with technology, than with socialisation processes that often discourage girls and young women from taking part.

In eight chapters spanning chronologically from 1973 to 2011, Katz covers the rise of hip hop DJs from their modest beginnings in the Bronx, to the establishment of DJ academies across the US and international DJ battles. Along the way, he examines the equipment and technological changes – many of which were inspired by DJs themselves – and their impact on DJing, as well as the cultural and identity spaces in which hip hop DJs operate. Katz uses stories collected from interviews with dozens of hip hop DJs to create what he calls a ‘narrative of the development of hip hop DJing’ (p. 6), centred primarily on the US. Groove Music is concerned with performative DJs, whom Katz identifies as ‘those who not only select recordings, but manipulate them in real time for audiences’ (p. 5). This manipulation lies at the core of hip hop DJing, although, as Katz shows, it has evolved dramatically since hip hop's early days. Nevertheless, what began as the isolation and repetition of a song's rhythmic break for dancers' enjoyment led to the emergence of breakdancing and provided aspiring MCs with the musical space to deliver their rhymes.

The early days of hip hop DJ culture are among the most entertaining chapters in Groove Music. In Chapter 1, ‘The breaks and the Bronx: 1973–1975’, Katz takes readers on a journey from the essence of hip hop DJing (the break), to the musical influences (everything), and perhaps most importantly, through the spaces and places in the Bronx where hip hop was born. A contributing factor to the book's engaging quality is the collection of stories from many of the young people who served as the vanguard of hip hop DJ culture. Chapter 2, ‘Mix and scratch – the turntable becomes a musical instrument: 1975–1978’ tells of young DJs' struggles to get their hands on the equipment they needed and then to get the precise sounds they wanted. Katz rightfully refers to them as ‘inventors and innovators’, and cites Rayvon Fouché's notion of ‘black vernacular technological creativity’ to illustrate how hip hop DJs approached their instrument – the turntable. Not only were hip hop DJs motivated to create what they needed themselves because they often lacked financial resources, but what they wanted the turntable to do in many cases couldn't be done. As an example, Katz offers an anecdote from DJ Ivan ‘Doc’ Rodriguez:

Or, as DJ Baby Dee declared: ‘The equipment wasn't made for what we wanted to do with it. So we urbanized it’ (p. 68). One of the book's most intriguing aspects is the case Katz makes for the turntable's consideration as a musical instrument. Admitting that the issue is ‘complex’, he still offers a set of criteria that can be used to redefine what is essentially a playback device as an instrument; these include, ‘[t]he object itself is either specifically designed or modified for making music’ and ‘[t]he sound it generates is considered to be music by a community of listeners’ (p. 62).

Further chapters chart the expansion of hip hop DJ culture. In Chapter 3 ‘Out of the Bronx and into the shadows: 1978–1983’ and Chapter 4, ‘Expansions: 1983–1989’, Katz looks at how hip hop spread first from the Bronx to Manhattan, then beyond – not only across the US, but internationally. It was also during this period that the role of the DJ was being progressively supplanted by the MC (rapper) and pre-recorded beats. Thus, Chapter 5, ‘Turntablism 1989–1996’ deals with the rise of a DJ culture that was no longer dependent upon MCs. DJ battles, which are competitions for supremacy, have always been an aspect of hip hop DJ culture, and Katz looks at them more closely in Chapter 6, ‘The art of war – the DJ battle: 1991–1996’. Covered in Chapter 7, ‘Legitimacy: 1996–2002’, is a detailed review of attempts to create notation for DJs, such as Turntabalist Transcription Methodology and scratchgraphique. In Chapter 8, ‘Falling barriers: 2002–2011’, Katz reviews technological developments – and setbacks, like DJ Hero and the rise of celebrity DJs – and the spread of DJ academies, where the next generation of DJs receive diplomas, and their DJ instructors a steady income and health benefits (no small matter in the US). Here, he also confronts the issue of gender and the marginalisation of women DJs. Finally, in the Conclusion, Katz makes it clear why all of this matters:

Groove Music offers a companion website with examples of music referenced in the text, as well as photographs, interviews and other materials. Thoroughly researched and filled with the voices of key figures in hip hop, Groove Music is breath-taking in scope and detail, and should be essential reading for anyone who wants to understand more about DJ culture – hip hop or otherwise – the spaces in which it came to life, and the challenges and opportunities that lie ahead.