When a medium is rapidly heated and cooled, heat transfers to its surroundings as sound. A controllable source of this sound is realized through joule heating of thin, conductive films by an alternating current. Here, we show that arrays of these sources generate sound unique to this mechanism. From the sound alone, we spatially resolve current flow by varying the film geometry and electrical phase. Confinement concentrates heat to such a degree that the film properties become largely irrelevant. Electrical coupling between sources creates its own distinctive sound that depends on the current flow direction, making it unusually sensitive to the interactions of multiple currents sharing the same space. By controlling the flow, a full phased array can be created from just a single film.

当介质快速加热和冷却时，热量会以声音的形式传递到周围环境。这种声音的可控源是通过交流电对导电薄膜进行焦耳加热来实现的。在这里，我们展示了这些源的阵列会产生这种机制特有的声音。仅根据声音，我们通过改变薄膜几何形状和电相位来空间解析电流。限制将热量集中到这样的程度，以至于薄膜的性能变得基本上无关紧要。源之间的电耦合会产生自己独特的声音，该声音取决于电流的流动方向，使其对共享同一空间的多个电流的相互作用异常敏感。通过控制流量，可以仅用单个薄膜创建完整的相控阵。