Despite their growing popularity, in-ear Earable / Hearable devices (i.e., ear-mounted wearables) face interaction challenges due to limited input space and compact form factors. To enhance interaction capabilities, researchers are exploring off-device hand-based input spaces above the neck using midair and onskin gestures. However, existing literature primarily focuses on axial swipes (i.e., horizontal and vertical), leaving nonaxial swipes (i.e., unidirectional swipes with varied orientations) and angular swipes (e.g., L, U, or V) largely underexplored despite their potential interaction advantages. To address this gap, we conducted a within-subject gesture motion analysis study with 24 participants, analyzing 5,568 swipes of varying shape, orientation, and complexity. Our results revealed preferred starting and ending regions for different unidirectional and angular swipe shapes, as well as intuitive swipe shapes within the off-device, above-neck manual interaction space. We further examine off-device swipe characteristics, discuss the feasibility of recognizing these earable gestures with current sensing technologies, and highlight their potential application in various scenarios. These findings broaden the understanding of off-device earable gestures and provide design insights for integrating suitable nonaxial and angular swipes alongside traditional axial gestures to enhance interaction with in-ear earable devices.

翻译：尽管入耳式耳戴/头戴设备（即耳戴式可穿戴设备）日益普及，但由于输入空间有限且形态紧凑，其在交互方面仍面临挑战。为提升交互能力，研究人员正探索利用空中手势与皮肤手势，在颈部以上基于离体手部输入空间进行交互。然而，现有文献主要聚焦于轴向滑动（即水平和垂直方向），非轴向滑动（即具有不同方向的单向滑动）和角滑动（如L、U或V形）虽具有潜在交互优势，却尚未得到充分研究。为填补这一空白，我们开展了一项包含24名被试的组内手势动作分析研究，对5,568次具有不同形状、方向及复杂度的滑动进行了分析。研究结果揭示了不同单向和角滑动形态的偏好起始与终止区域，以及在离体颈部以上手动交互空间中的直觉性滑动形状。我们进一步探讨了离体滑动特征，论证了基于当前传感技术识别此类耳式手势的可行性，并强调了其在多种场景中的潜在应用。这些发现拓展了对离体耳式手势的理解，为将合适的非轴向与角滑动手势融入传统轴向手势以增强入耳式设备交互提供了设计启示。