VR系列——Oculus Audio sdk文档：一、虚拟现实音频技术简介（8）——VR音频词汇

  主要针对前面提到的一些词汇做解释概况，如声音的衰减、早/迟反射、时间延迟、运动视差和混响等声音距离定位原理，以及方向定位的滤波器HRTF头部传递函数等。

VR音频技术项的定义。

Definitions of technical terms VR audio terms.

项	定义
消声	不产生回音；非常低或没有混响。
衰减	能量损失，在声音学中，通常是音量上的减少。
直接声音	直接传播到听者的声音，没有反射（相对混响的声音）。
早反射	相对早（比如在迟反射之前）到达听者位置的反射的声音。
头部相关脉冲响应（HRIR）	与特定人体集合交互的声音，其效应的形式化描述。用于创建头部相关的传递函数（HRTF）。
头部相关传递函数（HRTF）	用头部相关脉冲响应（HRIR）对声信号进行变换。用于模拟从特定的方向与特定的人体的几何形状的声音的相互作用的影响。
头影	头倾斜导致耳朵与声源之间的声音衰减。
初始时间延迟	直接声音与它的首次反射到达的间隔。
两耳水平差（ILD）	两耳之间声音的水平或音量差。
两耳时间差（ITD）	声音到达两只耳朵之间的时间差。
迟反射	相对晚（比如在早反射之后）到达听者位置的反射的声音。
运动视差	当移动的物体远离观察者时，它们表观的传播速度减少。例如，在水平方向移动的飞机看起来比附近的汽车开得慢多了。因此，物体的表观移动速率可以作为距离的提示。
耳廓	耳朵的可见部分，位于头部以外。
混响的声音	在抵达听者位置之前就反射或回荡的声音（相对于直接声音）。
混响	表面声音的反射，或在一个由混响引起的空间中的短暂持续声音。
声音定位	1.确定声音起源位置的过程；或者2.基于听觉线索操作的物体位置建议。
声音空间化	三维空间内声音的表现形式。

Term	Definition
Anechoic	Producing no echoes; very low or no reverberation.
Attenuation	A loss of energy; in acoustics, typically a reduction in volume.
Direct Sound	Sound that has traveled directly to the listener without reflecting (versus reverberant sound).
Early Reflections	Reflected sounds that arrive relatively soon at a listener’s location (i.e., before Late Reflections).
Head-Related Impulse Response (HRIR)	A formal characterization of the effect of sound interacting with the geometry of a particular human body. Used to create head-related transfer functions.
Head-Related Transfer Function (HRTF)	A transformation of an acoustic signal using a head-related impulse response. Used to simulate the effects of interaction of a sound originating from a specific direction with the geometry of a particular human body.
Head Shadowing	The attenuation of sound caused by the head lying between an ear and the sound source.
Initial Time Delay	The interval between the arrival of a direct sound and its first reflection.
Interaural Level Difference (ILD)	The difference in a sound’s level or volume between the two ears.
Interaural Time Difference (ITD)	The length of the interval between when a sound arrives at the first ear and when it arrives as the second ear.
Late Reflections	Reflected sounds that arrive relatively late at a listener’s location (i.e., after early reflections).
Motion Parallax	When moving objects are father from a perceiver, their apparent speed of travel decreases; for example, a moving airplane on the horizon appears to be travelling more slowly than a nearby car. The a 9d49 pparent rate of travel of an object can therefore be used as a distance cue.
Pinnae	The visible portion of the ear that lies outside the head.
Reverberant Sound	Sound that has reflected or reverberated before arriving at a listener’s location (versus direct sound).
Reverberation	The reflection of sound off of a surface, or the temporary persistence of sound in a space caused by reverberation.
Sound Localization	The process of determining the location of a sound’s origin; or 2. the suggestion of an object’s location based on the manipulation of auditory cues.
Sound Spatialization	The representation of a sound within three-dimensional space.