Whether common appliances can generate high-frequency sound?
We visualized the sounds of 8 common appliances. As seen in the figure, the 8 appliances can all generate detectable high-frequency sounds, and they are very different. It’s because that, different appliances have different requiring voltages and currents, since resulting in different frequency of adapters, and finally leading to the imparity of sounds.
Whether the sounds are from adapters or the devices themselves?
We then experimented on 5 same lamps and their corresponding adapters to find out the reason of the difference. As shown in the figure, we found that difference in devices themselves can result in quite different sounds, while difference in adapters produces less different results. This is because that, for the same brand and same model of devices, the charging voltage and current are similar; while different devices may differ in thestructure and the way they are built, for example, there are so manyelectronic components inside, these components may generatedifferent sound when influenced by the continually On-and-OFF currents, so the high-frequency sounds of these devices may be some how different.
Whether the sounds from the same devices are stable over time and space?
we collected the sound signals of one device (for example, air conditioner) over 5 weeks. Results in the figure show that the sounds are temporally consistent. It’s because that the frequency is mainly the feature of the adapter and the device themselves.
