The effects of head mounted weight on comfort for helmets and headsets, with a definition of "comfortable wear time".

BACKGROUND: There are difficult tradeoffs when designing head-mounted equipment such as helmets, lights, cameras, or virtual or augmented reality displays. Increased functionality and battery life adds weight, which in turn reduces comfort. A successful product must balance both comfort and functionality to achieve its product engagement goals. OBJECTIVE: This study defines "comfortable wear time" as a new metric, and applies it to the domain of headsets in determining the relationship between headset weight and comfort. METHODS: Sixteen study participants wore four otherwise identical headsets weighted between 500g-600 g for up to two hours each in an office environment. If participants experienced more than "mild discomfort" (>3 on an NRS-11 discomfort scale), the trial ended early, and the comfortable wear time was recorded. Intensity and location of discomfort was rated at trial conclusion, and qualitative feedback collected. RESULTS: Higher weights were associated with shorter comfortable wear times. Not everyone could wear even the lightest headset (500 g) for the full two hours. Qualitatively, discomfort took many forms beyond the expected neck fatigue or contact pressure and included symptoms commonly associated with motion sickness, such as headache and dizziness. Finally, there were pronounced gender differences with females experiencing more severe discomfort with earlier onset. CONCLUSION: Heavier headsets were less comfortable for the lower quartile of participants -yielding an average of 11 fewer minutes of comfortable wear time per 33 g of weight added. Understanding the discomfort costs from adding weight empowers product teams to find the correct balance to meet their product engagement targets.