The planes make a weirdly musical diatonic hum, like bagpipes playing two drones at once.
The swift revolution of each of these bodies causes a swish, or musical hum, in the air.
The gyros ran down with a sweet musical hum and the cooling motors chimed prettily.
She heard the hum of bees and birdsong, the sound of it clear and musical and ripe.
A musical hum outside awoke an echo of softly thudding feet.
It simply hung in the air and sounded a soft musical hum.
With an almost musical hum of activity, a swirling vortex of molecules began to reorganize themselves inside the replicator's service area.
When he amplified the signal, a musical hum filled the room.
Sometimes the wind made a low, musical hum as it vibrated in the wires..
Their cries were varied and eerie: long, soft, musical hums like nothing I'd ever heard before.