To reduce the free-jet noise of auxiliary nozzles in air-jet looms and clarify the influence of outlet-hole arrangement on jet flow and acoustic radiation, two multi-hole auxiliary nozzles, namely a six-hole central array and a fifteen-hole circumferential array, were designed while keeping the main nozzle body and supply condition consistent. Large eddy simulation (LES) was used to obtain the near-field velocity and pressure-fluctuation distributions of the three-dimensional jets. The Ffowcs Williams-Hawkings (FW-H) acoustic analogy was then employed to predict the sound pressure level (SPL) spectra and directivity at different far-field observation angles, and the predictions were validated by a microphone-array experiment. Dynamic mode decomposition (DMD) was further applied to extract the dominant coherent structures and reveal the noise-generation mechanism associated with different outlet-hole arrangements. The results show that the six-hole central array has a higher exit peak velocity, a longer potential core, and stronger jet concentration, whereas the fifteen-hole circumferential array enhances the interaction and mixing among multiple fine jets, slows down the decay of the downstream centerline velocity, and reduces the contribution of large-scale coherent structures to far-field acoustic radiation. At the same observation distance, the spectral peak SPL of the fifteen-hole auxiliary nozzle is 98 dB, which is 9 dB lower than that of the six-hole auxiliary nozzle (107 dB). At an observation distance of 100 mm, the overall SPL of the fifteen-hole auxiliary nozzle is reduced by approximately 15 dB compared with that of the six-hole auxiliary nozzle. The results provide a reference for the low-noise structural design of auxiliary nozzles in air-jet looms.