Do Bystanders and Dialog Participants Differ in
Preferences for Telecommunications Channels?
-- The Effects of Noise and Delay --
Why?
Nigel Ward
Anais G. Rivera
Alejandro Vega
University of Texas at El Paso
The Mystery
Mobile telephone conversations are often banned
because they can be annoying to bystanders.
But why are they more annoying than face-to-face conversations?
Is it the volume? Perhaps in part, but cell phone
conversations are more annoying even when no louder than
face-to-face conversations (Monk et al. 2004a)
Is it the lack of an audible interlocutor, inducing a
psychological “need to listen”? Perhaps in part, but this
doesn’t explain the annoyance (Monk et al. 2004b)
Is it the Channel?
Channel properties affect user perceptions.
The E-model can predict these, for infrastructure design purposes.
Transmission Rating Factor (ITU-T Rec G.107)
R = Ro – Is –Id –Ie-eff + A
Ro = signal-to-noise ratio
Is = simultaneous impairment
Id = delay impairment factor
Ie-eff = equipment impairment factor (e.g. codec)
A = advantage factor
But what about bystander preferences?
Potential Significance
Hypothesis 1:
For telecommunication channels, bystanders preferences
differ from users preferences
If true, there may be a technological fix to the problem
Today:
In a Possible Future:
NO B>70
PHONES!
Perceptions of Delay
We know that delay affects talkers’ perceptions
How Line Delay Affects
Conversation Dynamics
(Emling & Mitchell 1964)
Likely 1st Order Effects:
• more awkward silences
• more overlaps
Likely 2nd Order Effects:
• more explicit
turn-taking cues
Likely Effects on Bystanders
lack of audible
interlocutor
channel
properties
• delay
• noise
handset
properties
• lack of
sidetone
• low volume
• echo
cognitive
effects
changed
speaking style
• uncertainty
about receipt
• frustration
• cognitive load
different
situation
at remote end
• incongruous
speaking styles
• incongruous
topic
• lack of shared
awareness
• loud
• exaggerated
prosody
• etc.
involuntary
listening
negative
impressions
of talker
• bossy
• show-off
• insensitive
• etc.
feeling of
embarrassment
annoyance
negative
attitudes to
cell phones
Hypothesis 2
Hypothesis:
Bystanders dislike channel delay more than do
talkers
where we measure “more” relative to a standard
impairment: codec quality
Experiment Design
High Noise
Low Delay
Talkers’
Perception
Bystanders’
Perception
good
good
(Cn)
Low Noise
High Delay
(Cd)
good
less good
T Δ = TCn - TCd B Δ = BCn - BCd
Hypothesis 2:
compared to talkers, bystanders dislike delay more
i.e. T Δ < B Δ, i.e. T Δ - B Δ < 0
unfortunately not supported
GSM-FR
150 ms
G.711
350 ms
Software/Hardware Configuration
extra delay (CD)
or extra noise (CN)
recorder
• channels emulated on Linux machines
• talkers in different rooms
Procedures
Two Talkers
1.
2.
3.
4.
5.
6.
welcome
dialog with Cn or Cd
questionnaire
dialog with Cd or Cn
questionnaire
debrief
Two to Eight Bystanders
1.
2.
3.
4.
5.
6.
welcome
overhear
questionnaire
overhear
questionnaire
debrief
usually with same stimuli, different judges
sometimes with same judges, different stimuli
(when talkers were later used as bystanders)
sometimes with same judges, same stimuli
(when talkers later listened to recordings of themselves)
Experiment Conditions (1)
Distance from Talker to Bystanders
• > 4 meters
• ~ 2 meters
• ~ 0.5 meters
Distractors
• pizza and friends
• magazines
• none (paying attention)
Dialog Content
Cn
• multi-digit number exchange
• free dialog
• single-digit number exchange
Cd
Experiment Conditions (2)
Presentation
• live
• recorded, played over speakers
• matched-content extracts, headphones
Subjects
• naive students
• experts
Survey Format
• forced choice
• 4 choices
• 11 point scales
Results
TΔ = talker preference re channel quality (Cn – Cd)
BΔ = bystander preference re less-annoying (Cn – Cd)
Results
On the last experiment:
Subjects’ preferences for Cn over Cd,
as talkers and as bystanders
Summary
Summary results for Hypothesis 2:
• Across 59 dialog stimulus-pairs, in various conditions
- bystanders seemed to dislike Cn more than did
talkers,
contrary to hypothesis 2
- however the difference was small and not consistent
(averaging 1.42 vs 1.47 on a scale from 0 to 3)
• Even under unrealistically exaggerated conditions,
line delay does not consistently impact bystanders
Summary Results for Hypothesis 1:
• No evidence that bystanders and dialog participants
differ in preferences
The Mystery Remains
Do Bystanders and Dialog
Participants Differ in Preferences
for Telecommunications Channels?
-- The Effects of Noise and Delay -Nigel Ward
Anais G. Rivera
Alejandro Vega
University of Texas at El Paso
Do Bystanders and Dialog Participants Differ in
Preferences for Telecommunications Channels?
-- The Effects of Noise and Delay --
Why?
Nigel Ward
Anais G. Rivera
Alejandro Vega
University of Texas at El Paso
T
Dialog-Based Evaluation of Mobile Phone Infrastructure
Phase 1
A. Your opinion of the connection you have just been using.
(Please place a line crossing the axis at the appropriate point.)
first
dialog
10
8
6
4
2
0
excellent
good
fair
second
dialog
poor
bad
10
8
6
4
2
0
excellent
good
fair
poor
bad
B. What differences did you notice between the two connections?
C. What do you think affected your ratings of the two connections?
date ___________
session ________
subject A B
recording# 1 _________
recording# 2 _________
B
Dialog-Based Evaluation of Mobile Phone Infrastructure
Phase 2
A. Sometimes conversations can be annoying to bystanders, independent of the content, due to the way
the the speaker was talking. Considering the potential for annoyance due to the speaking style, please
give your opinion of the sample.
(Please place a line crossing the axis at the appropriate point.)
first
dialog
10
8
6
4
2
0
excellent
good
fair
poor
bad
second
dialog
10
8
6
4
2
0
excellent
good
fair
poor
bad
B. What differences did you notice between the two samples?
C. What do you think affected your ratings of the two samples?
date ___________
session ______
subject A B
recording# 1 _________
recording# 2 _________
R
Dialog-Based Evaluation of Mobile Phone Infrastructure
Phase 3
A. Sometimes conversations can be annoying to bystanders, independent of the content, due to the way
the the speaker was talking. Considering the potential for annoyance due to the speaking style, please
give your opinion of the sample.
(Please place a line crossing the axis at the appropriate point.)
first
dialog
10
8
6
4
2
0
excellent
good
fair
poor
bad
second
dialog
10
8
6
4
2
0
excellent
good
fair
poor
bad
B. What differences did you notice between the two samples?
C. What do you think affected your ratings of the two samples?
date ___________
session ______
subject A B
recording# 1 _________
recording# 2 _________