# Experimental Investigation of a Tubular Front Cavity for Wind Noise Suppression in MEMS Microphones of Mobile Devices

## TL;DR

This study shows that elongating small-diameter tubes can reduce wind noise in MEMS microphones used in smartphones, offering a compact alternative to traditional windscreen methods.

## Contribution

The study experimentally demonstrates that tube length affects wind noise suppression in MEMS microphones, with effectiveness dependent on cavity diameter.

## Key findings

- For 1 mm diameter tubes, longer lengths significantly reduce noise and steepen high-frequency roll-off.
- Noise suppression effectiveness diminishes for 2 mm and 3 mm diameter tubes due to external flow excitation.
- Longer tubes reduce sensitivity to wind speed and oblique incidence, but only for small-diameter cavities.

## Abstract

Wind-induced noise remains a critical engineering challenge for MEMS microphones in compact consumer electronics such as smartphones, where spatial constraints limit conventional noise control solutions. This study experimentally investigates the suppression of flow-induced wind noise by a straight tube serving as the front cavity of a microphone, using a precision measurement microphone for data acquisition. Controlled experiments were conducted in both a flow duct for parametric isolation and an anechoic chamber for real-world validation. Results demonstrate a strong diameter-dependent effect: for a 1 mm diameter, increasing tube length significantly reduces noise power spectral density and steepens high-frequency roll-off via enhanced internal viscous and thermal dissipation. This effect weakens for a 2 mm diameter and becomes negligible for a 3 mm diameter, where noise is dominated by external flow excitation at the tube inlet rather than internal propagation. Therefore, extending tube length is an effective noise control strategy only for small-diameter cavities. Furthermore, while increased wind speed and oblique incidence elevate PSD, a longer tube reduces this sensitivity. Because acoustic transmission loss—including potential effects like aperture diffraction and impedance mismatch—was not measured, any resulting improvement in the effective signal-to-noise ratio is strictly presented as a hypothesis requiring future electroacoustic validation. The consistent findings across both experimental environments provide clear design guidance: for compact MEMS microphone systems in portable devices, elongating the front cavity is a viable passive noise control method only when the cavity diameter is sufficiently small (<2 mm). This offers a practical, space-efficient alternative to traditional windscreen-based approaches in portable devices.