Field Recording in Dense Urban Monsoons

Recording the texture of heavy rain in a dense concrete environment like Mumbai presents unique acoustic challenges. The high sound pressure levels of rain falling on tin roofs, combined with constant low-frequency traffic rumble, can easily saturate delicate capsules.

Here is a breakdown of the equipment and techniques we utilized during our June field expedition.

The Setup

• Microphones: Ambient recordings were captured using an ORTF pair of small-diaphragm condenser mics.
• Wind Protection: Rycote blimps with wet-weather covers (crucial for maintaining transparency while preventing water droplets from hitting the capsules).
• Recorders: High-headroom preamps with 32-bit float recording to prevent clipping during sudden thunder cracks.

Key Acoustic Findings

1. The Concrete Acoustic Chamber

In narrow alleyways, the concrete acts as a giant reverberant chamber. Mid-frequency reflections (200Hz - 800Hz) build up rapidly, causing a muddy, boxy sound. We corrected this by angling the ORTF configuration slightly downward to capture direct ground splashes while utilizing the natural diffusion of the buildings.

2. High-Frequency Absorption

Heavy downpours create a dense mist that physically absorbs high frequencies above 12kHz. To capture the crispness of individual drops, we placed secondary contact microphones directly onto metal pipes and glass windows.

Sonic Compilation

These recordings will be utilized to test the transient responsiveness and spatial reproduction of the upcoming UNT series monitors. Raw WAV files will be made available to Auralis waitlist subscribers in the next dispatch.