Abstract: During an initialization of a head pose tracker for a spatial audio system, a spatial audio ambience bed is rotated about a boresight vector to align the boresight vector with a center channel of the ambience bed. The boresight is computed using source device motion data and headset motion data. The ambience bed includes the center channel and one or more other channels. An ambience bed reference frame is aligned with a horizontal plane of a headset reference frame, such that the ambience bed is horizontally level with a user's ears. A first estimated gravity direction is fixed (made constant) in the ambience bed reference frame. During head pose tracking, the ambience bed reference frame is rolled about the boresight vector to align a second estimated gravity direction in the headset reference frame with the first estimated gravity direction fixed in the ambience bed reference frame.

Abstract: During an initialization of a head pose tracker for a spatial audio system, a spatial audio ambience bed is rotated about a boresight vector to align the boresight vector with a center channel of the ambience bed. The boresight is computed using source device motion data and headset motion data. The ambience bed includes the center channel and one or more other channels. An ambience bed reference frame is aligned with a horizontal plane of a headset reference frame, such that the ambience bed is horizontally level with a user's ears. A first estimated gravity direction is fixed (made constant) in the ambience bed reference frame. During head pose tracking, the ambience bed reference frame is rolled about the boresight vector to align a second estimated gravity direction in the headset reference frame with the first estimated gravity direction fixed in the ambience bed reference frame.

Abstract: A fastener (1) for holding together a group (7) of documents comprises a foldable sheet of, for example, paper divided into at least one anchor portion (2) and at least one tab portion (3, 4). Attachment means such as repositional adhesive provide for attachment of those portions to at least the first and last documents of the group upon being folded around an edge of the group. To assist with this, the sheet is marked with at least one fold line to be aligned with at least one edge of the group upon attachment of the anchor portion to the first document in the group, prior to folding the tab portion around that edge of the group for attachment to the last document in the group. Preferred embodiments employ two mutually orthogonal fold lines that intersect at or outside the periphery of the fastener sheet.