Human Factors Design
Upcoming:
Today: CPD (final TLA)
Tues Dec 7: Extra office hours (3-5 pm)
Wed Dec 8: Quizette 4 (Last day of Class)
Fri Dec 10: Paper (4 pm CCIT 4015)
Thinking of a Career in Human Factors Design?
 Major Areas

of Acoustic Research
Alarms and Sirens
• Train horn, Car alarm, Alarm clock
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Auditory Spatial Display
• Sonification for the blind, auditory
enhancement of complicated visual
environments

Consumer product advertising
• Earcons and auditory icons

Room design
• Home theatre systems, concert halls,
classrooms
Marketing Auditory Display

Earcons & Auditory Icons
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Auditory icons: Ecologically valid cue for object
• E.g., Cow = ‘Moo’

Earcons: Artificial cue for object
• E.g., Intel = ‘Demo’
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Why use earcons?

Increase exposure of company
• Use of multiple modalities to improve memorability of
product
• Blind, low-vision access


Increasingly aged population with reduced visual capacity
Temporal control
• Ensure attention to company identification at correct
moment

Recency/primacy effects
• Non-invasive acoustic display to capitalize on memory
constraints
Earcon or Auditory Icon

Memorability of a picture

Experiment: Present picture with icon or earcon (Lemmens et al, 2001)
• Categorization of objects


Learn to match earcon/icon to stimulus
Accompany stimulus presentation with sound
• Reaction times faster with auditory icon


Slower with Earcon
Memorability of a sound

Experiment: Match sound to picture
• Varied directness of relationship

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Ecological (Auditory icon) = occur together in nature
Metaphorical (Earcon) = referent to object
• Mouse to non-Mouse squeaking
Random (Earcon) = referent to object
All sounds equally memorable
• Ecological and metaphorical better facilitate object memory
Room Acoustics

What is the goal?



Classroom/Office: communication
Concert hall: ‘warm’ sound, rich
acoustics
What are the constraints?

Room size
• Varies reverberation time


Classroom ideal >0.5 s (play demos)
Concert Hall ideal 1.2 – 1.8 s (play demos)
• First reflection >0.4 s
• Correlates with attenuation of signal

High ceiling increases reverberation time, but
diminishes intensity
• Solution: diffusion rafters
Specific Challenges of the Room

Materials

Concrete in schools
• Solid for building/long-term
• Poor acoustics & lots of reverb muddying the sound

People
• 80% of concert hall sound is absorbed by the audience

Sources of background noise

Ventilation systems
• Cheaper systems have noisier fans
• Typical classroom 50 dB background noise


Speech 60-65 dB at source, diminishes 3 dB every meter
• Back of room (4 meters) SNR = 1 dB
Outside noise (concert hall)
• Traffic and noise of city

Solution: acoustic tiling
Thank You for your Time!