Recently proposed Generalized Time-domain Velocity Vector (GTVV) is a generalization of relative room impulse response in spherical harmonic (aka Ambisonic) domain that allows for blind estimation of early-echo parameters: the directions and relative delays of individual reflections. However, the derived closed-form expression of GTVV mandates few assumptions to hold, most important being that the impulse response of the reference signal needs to be a minimum-phase filter. In practice, the reference is obtained by spatial filtering towards the Direction-of-Arrival of the source, and the aforementioned condition is bounded by the performance of the applied beamformer (and thus, by the Ambisonic array order). In the present work, we suggest to circumvent this problem by directly modeling the impulse responses constituting the GTVV time series, which permits not only to relax the initial assumptions, but also to extract the information therein in a more consistent and efficient manner, entering the realm of blind system identification. Experiments using measured room impulse responses confirm the effectiveness of the proposed approach.

翻译：近期提出的广义时域速度矢量（GTVV）是球谐函数（即Ambisonic）域中相对房间脉冲响应的泛化形式，可实现对早期回声参数（各反射分量的方向与相对延迟）的盲估计。然而，GTVV的闭式表达式推导需满足若干前提假设，其中最关键的是参考信号的脉冲响应需为最小相位滤波器。实际应用中，参考信号通过对声源到达方向进行空间滤波获取，上述条件受限于所用波束形成器的性能（进而受Ambisonic阵列阶数约束）。本研究提出直接对构成GTVV时间序列的脉冲响应进行建模以规避此问题，该方法不仅可放宽初始假设，还能以更一致高效的方式提取其中蕴含的信息，从而进入盲系统辨识领域。基于实测房间脉冲响应的实验验证了该方法的有效性。