The HONK! Street Band Movement and its family of festivals – participatory, grassroots, and non-commercial festivals featuring activist or community-based brass and percussion ensembles – have since 2006 used sound and music as a means for inviting people to assemble in public, in-person festivals in ways understood by participants as contesting hegemonic power, reclaiming public space, and facilitating collective solidarity via joyful brass and percussion performances. Yet even as HONK! musicians view their acoustic, mobile, and collective music-making as something which might reclaim public space for more inclusive and democratic uses, an increasing emergence of HONK! bands composed entirely of women, non-binary, and transgender musicians reveals that the inclusive space that HONK! festivals and bands conceive of and seek to produce may be organized in ways that hinder gender-marginalized musicians from feeling like they can participate. In this paper, I argue that gender-marginalized HONK! musicians practice a mode of listening in their bands that “listens out” (Lacey 2013) for diverse voices and perspectives in a radically open, anticipatory, and intersubjective way. Through practices of listening out and with careful attention for one another, gender-marginalized HONK! bands produce spaces that facilitate learning and build confidence among musicians working to find their musical and political voices. I argue that listening out reveals forms of exclusion present and reconfigures relations of attention such that diverse voices might more easily resonate within the broader HONK! movement. In turn, the HONK! movement’s reclamations of public space might be more informed by the lived experiences of its participants.