Bubble-particle attachment is crucial in froth flotation, for recovering valuable minerals. This study explores how ultrasound promotes this attachment. A centimeter-scale cell was built, in which a single stagnant bubble, held on a capillary tip, was immersed in a mechanically agitated particle suspension and intermittently sonicated with a 36 kHz standing wave. Particle size (66 µm and 176 µm glass beads), hydrophobicity, ultrasound parameters (intensity and duration), and stirrer speed were systematically varied, and the resulting surface coverage was optically quantified. Sonication raised coverage because the secondary acoustic radiation force pulled particles toward the bubble. For hydrophobized 66 µm beads, depending on rotational speed, a complete, stable monolayer of 100 % formed within 20 s once the acoustic pressure exceeded 0.9 bar. The 176 µm beads plateaued at approximately 50 % unless their number density was increased six-fold. Attachment remained stable under the highest tested rotational speed and acoustic pressures, provided the particles were hydrophobic and encountered a free bubble surface. Conversely, excessive acoustic streaming at high stirrer rates and very strong sonication intensity reduced coverage, implying that a narrow operating range in which the secondary radiation force dominates but acoustic streaming drag stays sub-critical might exist. Comparison with classical collision/attachment models shows that ultrasound may modify particle flux, contact time and film drainage, thus raising the attachment probability. The results deliver practical guidance for tuning acoustic wave amplitudes, exposure time and background hydrodynamics before pilot-scale flotation trials.