Acoustics-based techniques are investigated to focus and bunch nanoparticle beams. This process allows us to overcome the prominent problem of the longitudinal and transverse mismatch of particle-stream and x-ray-beam size in single-particle and single-molecule imaging at x-ray free-electron lasers (XFELs). It also enables synchronized injection of particle streams at kilohertz repetition rates. Transverse focusing concentrates the particle flux to the size of the (sub)micrometer X-ray focus. In the longitudinal direction, focused acoustic waves can be used to bunch the particle to the same repetition rate as the x-ray pulses. The acoustic manipulation is based on simple mechanical recoil effects and could be advantageous over light-pressure-based methods, which rely on absorption. The acoustic equipment is easy to implement and can be conveniently inserted into current XFEL endstations. With the proposed method, data collection times could be reduced by a factor of 10⁴. This work does not just provide an efficient method for acoustic manipulation of streams of arbitrary gas-phase particles, but also opens up wide avenues for acoustics-based particle optics.