Transcript Auditory Display

Auditory, Tactual, and
Olfactory Displays
Chapter 6
Auditory, Tactual, and Olfactory
Displays
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Hearing 
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Auditory Display 
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Cutaneous Senses
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Tactual Display 
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Olfactory Sense 
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Olfactory Display 
Hearing
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Nature and Measurement of Sound 
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Anatomy of the Ear 
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Conversion of Sound Waves to Sensations 
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Masking 
Hearing —Nature and Measurement of
Sound
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Frequency of Sound Waves
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Sinusoidal (or sine) wave
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Pitch
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Intensity of Sound
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Complex Sound
Fig 6-1
Hearing —Nature and Measurement of
Sound
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Intensity of Sound
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定義: power per unit area
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單位: decibel (dB)
SPL(dB) = 10 log (P12/P02)= 20 log (P1/P0)
P0= 20μN/m2 (reference)
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Sound-level-meter (combine 各種頻率)
Weighting networks: A, B, C (ANSI)
Fig 6-2
(例) Sound level (A)=45dB, SLA=45dB, 45dB(A)
Hearing —Nature and Measurement of
Sound
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Complex Sound
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Individual sine waves: combine
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Sound Spectrum: Spectral analysis
Fig 6-3
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Sound → frequency bands, intensity
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Frequency-band analyzer: Fig 6-4
bandwidth小 → more detail, lower sound level
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ANSI: 10 bands
center freq.: 31.5, 63, 125,……
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Hearing —Anatomy of the Ear
Fig 6-5
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Middle Ear: Acoustic (or aural) reflex
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Hearing —Conversion of Sound Waves
to Sensations
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Sensitive: 1000 – 5000 Hz.
－End
Hearing —Masking
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Operational definition:
Masking sound → threshold elevation
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Selecting auditory signal:
需考慮環境噪音之 masking effect
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Masking effect of pure tone
Fig 6-6
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Greatest effect: near the freq. (of masking tone) &
its harmonic overtones
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Higher intensity: spread to higher freq.
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Critical band: 可產生masking effect之頻率範圍
Higher freq. → larger critical band
－End
Auditory Display
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Auditory display preferable: p.169 
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Detection of Signals 
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Relative Discrimination 
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Absolute Identification 
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Localization 
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Principles 
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Specific Purpose 
Auditory Display — preferable
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When the origin of the signal is itself a sound
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When the message is simple and short
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When the message will not be referred to later
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When the message deals with events in time
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When warnings are sent or when the message
calls for immediate action
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When continuously changing information of
some type is presented
Auditory Display — preferable
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When speech channels are fully employed
When the receiver moves from one place to
another
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When a verbal response is required (compatible)
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When the visual system is overburdened
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When illumination limits use of vision
－End
Auditory Display —Detection of Signals
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SDT (a function of masking)
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Quiet surroundings
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40 – 50 dB above threshold
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Duration: 至少 500 ms
Noisy
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Min.: 15 dB above masked threshold
Max.: 25 dB above masked threshold
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Midway: masked threshold — 110 dB
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S/N ratio in the most sensitive 1/3 octave band
Auditory Display —Detection of Signals
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Use of filters
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Predominant freq. of noise ≠ signal
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Method: filter out some of the noise
raise intensity of the remaining sound
→ increase S/N ratio
Increasing detectability (p.171)
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Freq. 不同
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Sound location 不同: phase-shift, both ear vs. one ear
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在敏感頻帶(1000 – 4000 Hz)取4個以上主要頻率組成
complex sound, 較不易masked
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Auditory Display —Relative Discrimination
Measure: JND
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Discrimination of Intensity differences
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Above 60 db (smaller JND)
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Freq.: intermediate (1000, 4000)
Fig 6-7
Discrimination of Frequency differences
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At least 30 dB
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Freq. 太高→ JND 上升 (discrimination↓)
Freq. 低→ 易與 noise相混
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500 – 1000 Hz 適中
Fig 6-8
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Auditory Display —Absolute Identification
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Multidimensional coding 為佳
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More dimensions
Fewer steps
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Auditory Display —Sound Localization
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Stereophony: phase, intensity difference
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定位能力差：方向前後相反，距離高估
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Detect motion of a sound
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MAMA (Minimum Audible Movement Angle)
depend on
 Speed of movement
 Initial position: 正前方(0º): 5º, 側邊(90º)：33º
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較視覺差
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Auditory Display — Principles
P. 176
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Fig 6-9
General Principles
 Compatibility (e.g. high freq: up)
 Approximation: two-stage signals
Attention-demanding signal
 Designation signal
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Dissociability
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Discernible from any ongoing audio input
Parsimony
 Invariance
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1/3
Auditory Display — Principles
P. 176
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2/3
Fig 6-9
Principles of Presentation
 Avoid extremes of auditory dimensions
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Establish intensity relative to ambient noise level
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Not masked
Use interrupted or variable signals
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(e.g.) startle response
Adaptation
Do not overload the auditory channel
Auditory Display — Principles
P. 176
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3/3
Fig 6-9
Principles of Installation of Auditory Displays
 Test signals to be used
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Representative sample of potential user population
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Avoid conflict with previously used signals
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Facilitate changeover from previous display
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Auditory Display —Specific Purpose
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Warning & Alarm Signals
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聽覺特別適合
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那一種聲音較適合
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Intensity:
Fig 6-10 6-12
Fig 6-11
SRT: 強, CRT: 中等
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Recommendations P.180
1/3
Auditory Display
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—Specific Purpose 2/3
Warning & Alarm Signals
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Recommendations P.180
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200 – 5000 Hz
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Travel long distance: below 1000 Hz
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Bend around obstacles: below 500 Hz
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Modulated signal: different enough
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Frequency different from bk.
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If different warning signals used: discriminable,
moderate-intensity
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Separate communication system
Auditory Display
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—Specific Purpose 3/3
Aids for the Blind (clear-path indicators)
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Pathsounder
Single-object sensor
Sonic pathfinder
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須 walk more slowly
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問題
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Tactile Display
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類型: Mechanical vs. Electrical 
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Substitutes for Hearing 
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Substitutes for Seeing 
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Discussion 
Tactile Display —Mechanical vs.
Electrical
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1/2
Coding
Coding
Location
Frequency
Intensity
Duration
Phase
Mechanical
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？
Electrical
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Tactile Display —Mechanical vs.
Electrical
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2/2
Electrical ＞ Mechanical
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Less bulk
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Lower power requirement
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Independent of skin temperature
Electrical ＜ Mechanical
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Elicit pain
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Tactile Display —Substitutes for Hearing
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Reception of Coded Messages
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5(chest location) × 3(intensity) × 3(duration)
=45 pattern (26 letters, 10 numbers, 4 words)
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38 word/min ＞ Morse code (24 word/min)
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Perception of Speech (×)
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Localization of Sound: intensity difference
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Ear (L&R): microphone
→Index fingers: vibrators
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Tactile Display
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—Substitutes for Seeing
Identification of Control
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Coding: Shape, texture, size
Fig 6-14
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Reading Printed Material
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Braille printing (6個位置: 橫2縱3)
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Optacon: Fig 6-15
optical-to-tactile converter
1/3
Tactile Display
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—Substitutes for Seeing
Navigation Aids
 Environmental features
Point features
 Linear features
 Areal features
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Fig 6-16
Guide to use map
Tactile Graphs Fig 6-17
 Incised-grid (bk) & raised lines: better
 Raised-grid (bk): OK
2/3
Tactile Display
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—Substitutes for Seeing
Tracking-Task displays
 Single-task:
Fig 6-18
＋quickening ≒ visual display
 quickening: predictor display
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future consequences of a control
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Dual-task:
visual-tactile (primary-secondary)
﹥visual-visual
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3/3
Tactile Display —Discussion
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可用於 visual, auditory
Overburdened 時
Blind
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Olfactory Sense
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1/2
Mechanism
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Receptors:
鼻腔 olfactory cell 之 olfactory hairs
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Stimulus:
揮發性分子之部份
Olfactory Sense
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2/2
特性
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High false-alarm rate
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Absolute identification:
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15-32 種 odor (complex stimulus)
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3-4 種強度
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Identification 差:可能因字彙少
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Effective: detecting the presence of an odor
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Olfactory Display
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缺點:
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Reliability 差
(例) stuff nose; Adaptation 快
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Control 難
優點: 傳播易
用途: warning
(例) 瓦斯(gas), 礦坑(mine)
防火系統: CO2＋冬青味
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適用: closed space, vast areas
－End