©
2012 mh acoustics LLC. All rights reserved.
Introduction
The mh acoustics em32 Eigenmike®spherical microphone array is based on eigenbeam processing of
the incident soundfield. Each eigenbeam has the spatial response of corresponding spherical harmonics.
Eigenbeams are based of higher-order spatial derivatives, which are themselves related to the spherical
harmonic decomposition of the soundfield into its spatial components. Microphones that utilize spatial
derivatives of the acoustic pressure are well known to be sensitive to wind-induced noise.
For outdoor use is recommended to shield the Eigenmike®array with an acoustically transparent
windscreen if recording is done in an environment where wind might be present. The following manual
shows and describes how to assemble the simple windscreen. The windscreen is designed to easily
connect to em32 Eigenmike®arrays that have the aluminum shaft mount at the bottom of the em32
array. The windscreen was designed to be acoustically transparent, light in weight and fold flat to make
transport easy. We designed a simple mechanical structure that is easy to assemble and should be
robust to normal use. The windscreen fabric material is not waterproof so it should not be used in rain
or places where the microphone could get wet.
Windscreen assembly
The frame of the windscreen is composed of four mechanical pieces, a cylindrical base and three brass
hoops. These parts are shown in Figure 1. The black cylindrical polycarbonate base is designed to
easily mount onto the existing shock-mount holder for em32 systems that were constructed with an
aluminum bottom shaft. The circular base has slots and holes where three brass hoops are inserted.
Each brass hoop is the same size so there is no need to worry where each hoop goes into the base.
•Figure 1: Photograph of the four main mechanical components of the windscreen. The ring “base” and the three brass hoops.