Abstract: An example MR headset includes a housing with electronic components for presenting MR content, where the housing is configured to attach to a strap thereby forming a cavity, and defines an aperture, including a first opening on a first side of the MR headset and a second opening on a second side of the MR headset. The MR headset includes a speaker within the cavity positioned for minimizing intermodulation of the speaker within the cavity. The housing includes a fan to cool the electronic components and minimize noise interference. The MR headset includes an expansion chamber surrounding the inner surface of the fluidic channel that causes bias flow across the perforations. The MR headset includes microphones distributed along an outer surface of the housing for detecting audio content from a user, and each respective microphone is separated from the first and second opening by at least an audial-interference threshold distance.

Abstract: A stackable modular battery pack system is disclosed that includes at least two modular battery packs, including first and second battery packs. Each of the modular battery packs comprises a case in which a battery is disposed, first electrical contacts electrically connected to the battery and disposed on an exterior of the case, and second electrical contacts electrically connected to the battery, with the second electrical contacts being disposed on the exterior of the case. The case of the first battery pack is configured to releasably engage the case of the second battery case. The first electrical contacts are located on the first battery case and the second electrical contacts are located on the second battery case so that the first electrical contacts contact the second electrical contacts where the case of the first battery case and the case of the second electrical contacts are engaged.