Initial Distribution Transformer Analysis

We have analyzed the acoustic signatures of 34 distribution transformers across DC, and are excited to get more recordings at more times from more transformers soon.

But for now, let's dig into what we've found.

What Are We Looking For?

While there are many different ways that a transformer can produce noise, we are looking to track specifically the phenomenon of magnetostriction and its harmonics. This means we want to take an audio recording of transformer and look for 120 Hz.

Here's an example recording, taken from the transformer at 17th and R St NW on June 23, 2025 at about 3pm:

This includes the traffic on the street, me being unsteady with my hand, and the cooling fans that are internal to the transformer. With the recording in this form, it's tough to really get anything useful out of it. But we can use a Fourier transform to see what the individual frequencies are that make up the sound we're listening to: