感觉与知觉课件Chapter12

1. Auditory localization problem: How can he tell where the woman’s voice andthe music are coming from?2.Problem of reflected sound : How can he perceive the music clearly, with no “echo,” even though some of the soundfrom the speakers is bouncing off the wall and is arriving at his ears after a slight delay?3. Auditory scene analysis problem: How does he experience the woman’s voice as separate from the music and all the other sounds in the room?4. Problem of metrical structure: How does he perceive the music’s sound as perceptually organized in time, with a regular beat?1. Auditory localization Location cue (binaural cue and monaural cue); azimuth/elevation/distance对声源进行定位视觉系统：鸟和猫出现在视网膜上的不同位置听觉系统：鸟和猫的声音的频率不一样，引起耳蜗基底膜的不同反应，但是不包含位置信息，需要与声音的物理属性无关的其他线索双耳单耳位置线索方向角竖直方向上距离观察者有多高仰角距离Binaural cues use information reaching both ears to determine the azimuth (left–right position) of sounds.Interaural time difference (ITD)for low-frequency sounds Interaural level difference (ILD) for high-frequency soundsAcoustic shadow双耳时间差，只对低频率的声音使用双耳强度差（分贝之类的）波长远大于障碍物的大小，障碍物不影响声音传递波长小于障碍物的大小，衍射有一小块区域没有声音The three curves indicate interaural level difference (ILD) as a function of frequency for three different sound-source locations. Note that the difference in ILD for different locations is greater at higher frequencies频率较大时，用ILD；频率较小时，用ITDthe midline.无法可靠的确定中线上的声音的仰角The cone of confusion: all points on this cone have the same ILD and ITD.混乱锥Monaural cue for localization along the elevation coordinate 频谱线索，单耳线索关于声音的仰角mold：在耳廓里填充一些东西How localization changes when a mold isplaced in the ear? Affect the judgment ofelevation location, but not azimuth location.可能有两套表征spectral cue的系统2. The physiology of auditory localizationThe auditory pathway and cortexProcessing in the superior olivary nucleus is importantfor binaural localization because it is here that signalsfrom the left and right ears first meet.上橄榄核蓝色表示左耳信息，红色表示右耳信息下丘内侧膝状体上橄榄核对定位的作用左右耳信息在上橄榄核汇合核心区，蓝色带状区旁带状区The Jeffress neural coincidence model for auditory localizationITD detector and ITD tuning curve复合探测器coincidence detector，两侧信息同时达到它它才会发放Broad ITD Tuning Curves in Mammals This neuron fires best to sounds on themonkey’s right side and is broadly tuned自然环境中的ITD 的范围猴子的一个左侧听觉神经元的角度与发放强度左侧进入的声音在右侧有比较宽的tuning curve稀疏编码There are broadly tuned neurons in the right hemisphere that respond when sound is coming from the left and broadly tuned neurons in the left hemisphere that respond when sound is coming from the right. The location of a sound is indicated by the ratio of responding of these two types of broadly tuned neurons.The code for birds is a place code because the ITD is indicated by firing of neurons at a specific place. The code for mammals is a distributed code because the ITD is determined by the firing of many broadly tuned neurons working together.Localization in A1, the auditory belt area, the where and what pathways rBoth A1 and the posterior belt area show spatial tuning, but the latter shows a bettertuning.The what pathway (sound identification) starts in the anterior part of the core and belt and extends to the prefrontal cortex. The where pathway (sound localization) starts in the posterior part of the core and belt and extends to the prefrontal cortex.切掉或者冷却，声音定位受损但没有完全丧失带状区后部也对声音有表征，比A1更准确A1只对特定范围特定空间的声音有反应只有出现在偏好的区域时才反应posterior belt area 偏好的范围更小破坏猫的带状区前部，recognition 有影响，后部，localization 有影响Human auditory where and what pathways颞叶受损的人，定位没有受影响，识别受到影响3. Hearing inside rooms反射后的声音，间接声音，有一个delayPrecedence effect: when the delay between thelead and lag sounds is short (5-20ms), listenershear the sound as coming only from the leadspeaker. The effect helps to solve the direct/Indirect sound problem.Perceiving two sounds that reach the ears at different times优先效应会影响听到的声音的质量Architectural acoustics Consider (a) the amount of sound absorbed by the walls of the room, (b) the size and shape of the roomThe amount and duration of indirect sound produced by a room is expressed as reverberation time—the time it takes for the sound to decrease to 1/1000th of its original pressure (or a decrease in level by 60 dB).Acoustics in concert halls•Reverberation time: 2 seconds •Intimacy time: The time between when sound arrives directly from the stage and when the first reflection arrives. •Bass ratio: The ratio of low frequencies to middle frequencies that are reflected from walls and other surfaces.•Spaciousness factor: The fraction of all of the sound received by a listener that is indirect sound.Acoustics in lecture hallsReverberation time: < 0.6 seconds Signal-to-noise (S/N) ratio: > +10 dB建筑声学，房间的设计如何影响对声音的知觉混响时间音乐厅 2s 左右；歌剧院 1.5s 左右第一个反射回来的成分和直接成分的时间差低音反射回来的声音里低频到中频所占的比例空间感间接声音所占比例信噪比4. Auditory organization: scene analysisAuditory scene: the array of sound sourcesat different locations in the environmentAuditory scene analysis: the process bywhich the stimuli produced by each of thesources in the scene are separatedHow to separate the sources?1.Location2.Onset time3.Pitch and timbre When this passage is played rapidly, the low notes sound as though they are a melody played by one instrument, and the high notes sound like a different melody played by another instrument. This separation of different sound sources into perceptually different streams, is called auditory stream segregation.位置线索，混合的声音中没有位置表征如果两个声音有相同的起始时间，那声源基本相同；适用于自然环境音调和音色；在某一个范围内波动的音调/音色是一个整体即使是由同一个乐器演奏，依然会高音调知觉成一条旋律线，低音调知觉成另一条旋律线听觉信息流分离Stream segregation depends not only on pitch but also on the rate at which知觉组织的过程依赖于音调的变化和频率的变化tones are presented.缓慢呈现时觉得是一整条旋律线，快速呈现会出现上面的效应Separate streams are perceived when they are far apart in frequency, but the tones appear to jump back and forth between stimuli when the frequencies are in the same range.Although the notes in each ear jump up and down, the listener perceives a smooth sequence of notes. This effect is called the scale illusion, or melodic channeling.频率离的比较近的时候，知觉在两种声音之间跳动4. Auditory continuity5. Experience“Three Blind Mice.” (a) Jumping octave version. (b) Normal version声音的连续性出现一下然后停止把断开的部分用噪声填充会认为声音在噪声背后连续变化知觉经验一个儿歌的旋律把原来的旋律进行一些调整把一些音改成高一个八度如果对旋律没有先验知识就不会知觉到旋律有先验知识能跟上旋律，在高低之间跳跃melody schema 对旋律的记忆5. Auditory organization: perceiving meterMetrical structure: the underlying beat of the music (red arrows)Two common meters are duple (two beats per measure) and triple(three beats per measure)韵律，时间上的知觉，对音调的时间序列的加工一个小节中有两拍，duple有三拍，triple节奏型Metrical structure is indicated by the time signature of the composition and, in performance, is typically achieved by accentuating some notes by using a stronger attack or by playing them louder or longer. It is also subject to auditory perceptual grouping, even with a series of identical beats.Movement (e.g., bouncing frequency) can influence the perception of metrical structure (e.g., beat) through the vestibular system—the system that is responsible for balance and sensing the position of the body.Metrical structure and languageDifferent languages have different stress patterns. “the book ” in English (with book stressed) becomes “hon ga” in Japanese (with hon stressed).韵律结构听觉上的两可刺激attack 声音刚刚开始的时候把婴儿上下晃，给婴儿听同一频率的声音，看注视点，发现婴儿的运动影响了婴儿对声音刺激的频率知觉，婴儿注视注视点时间的长短表明听声音的时间如果去掉视觉刺激，这个效应依然存在婴儿本身不动，看其他人动，没有这个效应前庭系统Comparisons of how native English-speakers and Japanese-speakers (even 7-to 8-month-old infants) perceive metrical grouping supports the idea that thestress patterns in a person’s language can influence the person’s perception of grouping.英语觉得是短长短长日语觉得是长短长短和经验有关韵律的分组6. Connections between hearing and visionVentriloquism effect (visual capture) is an example of vision dominating audition. It occurs when sounds coming from one place (the ventriloquist’s mouth) appear to come from another place (the dummy’s mouth). Movement of the dummy’s mouth “captures” the sound.The two-flash illusion: when a single flash is accompanied by two tones and thesubject perceives two flashes. In this case, hearing modifies vision.腹语术效应，视觉捕获效应双闪错觉，视觉/听觉占主导地位没有声音，觉得是穿过了对方(a) No sound condition: the two balls were perceived to pass each other and continue moving in a straight-line motion.(b) Click-added condition: observers were more likely to see the balls as colliding 有声音，觉得是碰撞之后分离Coordinated receptive field in hearing and visionSome blind people use a techniquecalled echolocation to locate objects andperceive shapes in the environment.盲人可以通过一个回声系统训练，根据反射回来的声波学习位置和形状Blind subjectNormal subject。