Human Factors

1
Human Factors

• Rolla
• Session 3
• September 06, 2001

2
3 DIFFERENT METHODS OF FINDING THE HEIGHT OF AN
ALPHANUMERIC CHARACTER

• USE TABLE 4-2 ON PAGE 107
• STROKE WIDTH WOULD BE 1/6 TO 1/8,PAGE 103
• WIDTH OF CHARACTER ABOUT 3/5 OF HEIGHT, PAGE 104

3
3 DIFFERENT METHODS OF FINDING THE HEIGHT OF AN
ALPHANUMERIC CHARACTER

• USE FORMULA GIVEN IN CLASS BE SURE AND ADD THIS
  FORMULA TO THE BOTTOM OF PAGE 107
• H 0.0022D K1 K2
• K2 .075 FOR IMPORTANT READINGS
• K2 0 NONIMPORTANT??
• K1 .06 GOOD READING CONDITIONS
• K2 .16 BAD READING CONDITIONS

4
3 DIFFERENT METHODS OF FINDING THE HEIGHT OF AN
ALPHANUMERIC CHARACTER

• TO FIND THE STROKE WIDTH. FORMULA ON PAGE 107
• FIND HEIGHT BY DIVIDING STROKE WIDTH BY 1/6 TO
  1/8, PAGE 103
• WIDTH OF CHARACHER IS 3/5 HEIGHT, PAGE 104

5
ASSUMPTIONS YOU MUST MAKE

• HOW CLOSE ARE THE CHARACTERS??1 5 0 150 1 5
  0
• MUST BALANCE NUMBERS WITH SCALE FROM FIGURE 5-4,
  PAGE 138
• HOW FAR ARE CHARACTERS AWAY FROM SCALE MARKERS???

6
REVIEW OF CRITICAL DESIGN FEATURESFOR
QUANTITATIVE DISPLAYS

• USE DIGITAL IF ACCURACY IS REQUIRED.
• REMEMBER NUMBER MUST BE STATIONARY LONG ENOUGH TO
  READ
• IT IS DIFFICULT TO DETERMINE A TREND
• USE ROUND IF POSSIBLE
• FIXED SCALE MOVING POINTER IS BEST

7
REVIEW OF CRITICAL DESIGN FEATURESFOR
QUANTITATIVE DISPLAYS

• NUMBERS SHOULD INCREASE CLOCKWISE FOR ROUND -
  LEFT TO RIGHT FOR HORIZONTAL BOTTOM TO TOP FOR
  VERTICAL
• NUMBERS SHOULD ALWAYS FACE YOU
• POINTERS SHOULD HAVE AN ARROW OF ABOUT 20
  DEGREES, PAGE 139
• POINTER SHOULD EXTEND TO THE MIDDLE OF A CIRCULAR
  DISPLAY

8
REVIEW OF CRITICAL DESIGN FEATURESFOR
QUANTITATIVE DISPLAYS

• POINTER SHOULD NEVER COVER THE NUMBER
• POINTER SHOULD JUST TOUCH THE DIVISION MARKER
  NEVER OVERLAP
• NEVER USE FRACTIONS IN A SCALE
• THE DISTANCE BETWEEN SCALE MARKERS SHOULD BE
  UNIFORM

9
REVIEW OF CRITICAL DESIGN FEATURESFOR
QUANTITATIVE DISPLAYS

• FOR OPEN WINDOW DISPLAYS MAKE SURE YOU ALWAYS
  CLEARLY SEE TWO MARKED SCALE UNITS ON EITHER SIDE
  OF THE POINTER
• CAN COMBINE WITH QUALATATIVE MARKINGS BUT
  REMEMBER COLORS ARE HARD TO SEE IN LOW
  ILLUMINATION-RODS FUNCTION IN LOW LIGHT.

10
REVIEW OF CRITICAL DESIGN FEATURESFOR
QUANTITATIVE DISPLAYS

• CAN USE SPECIAL MARKINGS FOR QUALATIVE PART OF
  SCALE IF UNDERSTOOD BY MOST OF THE POPULATION
  SEE PAGE 146
• ALWAYS USE THE MAXIMUM READING DISTANCE WHEN
  DESIGNING.

11
RECOMMENDATIONS FOR SIGNAL WARNING LIGHTS PAGE
151

• USE TO WARN OF POTENTIAL DANGEROUS CONDITION
• USE ONLY ONE LIGHT
• USE FLASHING RATE OF 4/SEC
• MAKE SURE BRIGHTER THAN SURROUNDING LIGHTS

12
RECOMMENDATIONS FOR SIGNAL WARNING LIGHTS PAGE
151

• LOCATE WITHIN 30 DEGREES OF NORMAL LINE OF SIGHT
• USE RED FOR DANGER USE YELLOW FOR WARNING
• COULD COMBINE WITH SOUND (CHAPTER SIX)

13
SOUND

• INTENSITY
• FREQUENCY

14
MEASUREMENT OF INTENSITY
15
MEASUREMENT OF FREQUENCY

• CYCLES/SECOND Hz

16
DECIBLE COMPARISONPAGE 164

• 30 DECIBELS WHISPER
• 50 DECIBELS UMR LIBRARY,
  RESIDENTAL AREA-NIGHT
• 80 DECIBELS INSIDE SPORTS CAR 50MPH,
  PNEUMATIC DRILL 50 FT
• 100 DECIBELS SEVERAL BARS IN COLUMBIA, CUTOFF
  SAW

17
FREQUENCY AND PERCEPTION OF INTENSITY

• PAGE 592

18
MEASUREMENT OF SOUND(NOISE)

• PAGE 590

19
LOOK AT ANATOMY OF THE EAR

• PAGE 166

20
AUDITORY DISPLAYS USUALLY USED FOR WARNINGS

• HOW MANY???
• JUST NOTICABLE DIFFERENCES
• PAGE 174
• PROBABLY USE JUST ONE
• INTENSITY
• MASKING
• LOOK AT PAGE 170 MARK LAST SENTENCE NEXT TO LAST
  PARAGRAPH

21
FREQUENCY

• PAGE 180
• MOST COMMERCIAL UNITS ARE NOT PURE FREQUENCIES
  AND INTENSITY IS THE MOST IMPORTANT FACTOR
• MODULATION
• 1 TO 8 BEEPS PER SECOND
• OTHER SOUNDS
• SEE PAGE 178 TABLE 6-2

22
NOISE

• CAN BE MEASURED
• LOSS OF HEARING
• AGE, FIGURE 18-3, PAGE 596
• OCCUPATIONAL, PAGE 598

23
OSHA CONTROL OF NOISE EXPOSURE

• NOISE DOSE
• TIME ACTUALLY SPENT AT SOUND LEVEL DIVIDED BY THE
  MAXIMUL PERMISSIBLE TIME AT SOUND LEVEL SHOWN ON
  PAGE 604
• CONVERT DOSE TO 8 HOUR TIME WEIGHTED AVERAGE,
  PAGE 605 

24
ACTION LEVEL

• PERMISSIBLE EXPOSURE LEVEL
• HOW TO HANDLE NOISE PROBLEMS
• ISOLATE
• WEAR EAR PROTECTION
• NRR NOISE REDUCTION LEVEL
• SOUND LEVEL 7 NRR

25
PHYSIOLOGICAL EFFECTS OF NOISE

• STARTLE RESPONSE
• SMALL CHANGES IN HEART RATE
• CHANGES IN BREATHING
• NO AGREEMENT ON LONG TERM EFFECTS
• EFFECTS OF NOISE ON PERFORMANCE
• MIXED BAG STUDIES DIFFER IN RESULTS
• GENERAL CONCLUSIONS, PAGE 601

26
TACTUAL DISPLAYS

• FIGURE 6-13, PAGE 183
• IDENTIFICATION OF CONTROLS
• FIGURE 6-14, PAGE 186
• OLFACTORY DISPLAYS
• NATURAL GAS
• COMPUTER ROOM WARNING