http://erstwords.blogspot.com/2009/07/field-recording-and-experimental-music.html?m=1

“Maguchi Bay is a very ordinary fishing bay in Japan, a quiet place,” he recounts. “But the place was mysterious for me. There are many piers and breakwaters at the bay. When a contact mic is attached to one of the smallest and oldest piers, a huge amplitude of very low frequency sound is spread there. It was an unusual case in my field work. I discovered the low frequency about ten years ago. The mysterious thing for me is that this low-frequency vibration doesn’t relate to any sound that one hears in the air. First, I thought that it was the effect of the wind shaking the pier. But then it happened when there was no wind. Then, I thought that the sound was the vibration of a distant ship resonating across the bay, bouncing off the hill and making itself felt under water in the bay. But this guess was wrong too, as it would have been possible to detect the sound with the air microphone. It was so mysterious.

“My next guess was that there was a cause at the bottom of the sea,” he continues. “So I asked a fisherman who lives there. His answer was that the seabed terrain was extremely rugged. The water currents at the bottom of the sea are terrible. So the low frequencies came from the seabed. It was the vibration of the underwater currents hitting the pier supports where they met the seabed. The low frequency that I observed is an essential feature of Maguchi Bay and it’s directly related to the structure of that place. It only became a fishing bay when a lot of breakwaters were built to calm down the terrible sea currents. So there is a local history that I became aware of through the low frequency. I came to love the place, which I’ve known since I was a child, more than before. This is an ideal example of my field work.”