Do Bystanders and Dialog Participants Differ in Do Bystanders and Dialog Participants Differ in Preferences for Telecommunications Channels?Preferences for Telecommunications Channels?

-- The Effects of Noise and Delay ---- The Effects of Noise and Delay --

Nigel WardNigel WardAnais G. RiveraAnais G. RiveraAlejandro VegaAlejandro Vega

University of Texas at El PasoUniversity of Texas at El Paso

Why?

The MysteryThe 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?Is it the Channel?

Transmission Rating Factor (ITU-T Rec G.107)

R = Ro – Is –Id –Ie-eff + A

But what about bystander preferences?

Channel properties affect user perceptions.The E-model can predict these, for infrastructure design purposes.

Ro = signal-to-noise ratio Is = simultaneous impairment Id = delay impairment factor Ie-eff = equipment impairment factor (e.g. codec) A = advantage factor

Potential SignificancePotential 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>70PHONES!

Perceptions of DelayPerceptions of Delay

We know that delay affects talkers’ perceptions

(Emling & Mitchell 1964)

How Line Delay Affects How Line Delay Affects Conversation DynamicsConversation Dynamics

Likely 1st Order Effects: • more awkward silences • more overlaps

Likely 2nd Order Effects: • more explicit turn-taking cues

annoyance

lack of audibleinterlocutor

feeling ofembarrassment

channelproperties

involuntarylistening

• delay• noise• echo

negative attitudes tocell phones

handsetproperties

• lack of sidetone• low volume

negativeimpressionsof talker

• bossy• show-off• insensitive• etc.

changedspeaking style

• loud• exaggerated prosody• etc.

differentsituationat remote end

• incongruous speaking styles• incongruous topic• lack of shared awareness

cognitiveeffects

• uncertainty about receipt• frustration• cognitive load

Likely Effects on BystandersLikely Effects on Bystanders

Hypothesis 2Hypothesis 2

Hypothesis:

Bystanders dislike channel delay more than do talkers

where we measure “more” relative to a standard impairment: codec quality

Experiment DesignExperiment Design

High NoiseLow Delay(Cn)

Bystanders’Perception

Talkers’Perception

goodgood

Low NoiseHigh Delay(Cd)

less goodgood

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

by Wilcoxon sign test, chi-square, or matched-pairs t-test

G.711350 ms

GSM-FR150 ms

Software/Hardware ConfigurationSoftware/Hardware Configuration

• channels emulated on Linux machines

• talkers in different rooms

extra delay (CD) or extra noise (CN) recorder

ProceduresProcedures

1. welcome

2. dialog with Cn or Cd

3. questionnaire

4. dialog with Cd or Cn

5. questionnaire

6. debrief

1. welcome

2. overhear

3. questionnaire

4. overhear

5. questionnaire

6. debrief

Two Talkers Two to Eight Bystanders

usually with same stimuli, different judgessometimes 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)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 Cd• multi-digit number exchange• free dialog• single-digit number exchange

Experiment Conditions (2)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

ResultsResults

TΔ = talker preference re channel quality (Cn – Cd)BΔ = bystander preference re less-annoying (Cn – Cd)

ResultsResultsOn the last experiment:

Subjects’ preferences for Cn over Cd,

as talkers and as bystanders

SummarySummarySummary 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 Do Bystanders and Dialog Participants Differ in Preferences Participants Differ in Preferences

for Telecommunications Channels?for Telecommunications Channels?

-- The Effects of Noise and Delay ---- The Effects of Noise and Delay --

Nigel WardNigel WardAnais G. RiveraAnais G. RiveraAlejandro VegaAlejandro Vega

University of Texas at El PasoUniversity of Texas at El Paso

Do Bystanders and Dialog Participants Differ in Do Bystanders and Dialog Participants Differ in Preferences for Telecommunications Channels?Preferences for Telecommunications Channels?

-- The Effects of Noise and Delay ---- The Effects of Noise and Delay --

Nigel WardNigel WardAnais G. RiveraAnais G. RiveraAlejandro VegaAlejandro Vega

University of Texas at El PasoUniversity of Texas at El Paso

Why?

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.)

excellent

good

fair

poor

bad

10

8

6

4

2

0

firstdialog

seconddialog

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 Brecording# 1 _________recording# 2 _________

T

excellent

good

fair

poor

bad

10

8

6

4

2

0

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.)

excellent

good

fair

poor

bad

10

8

6

4

2

0

firstdialog

seconddialog

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 Brecording# 1 _________recording# 2 _________

B

excellent

good

fair

poor

bad

10

8

6

4

2

0

Dialog-Based Evaluation of Mobile Phone Infrastructure

Phase 3

date ___________session ______subject A Brecording# 1 _________recording# 2 _________

R

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.)

excellent

good

fair

poor

bad

10

8

6

4

2

0

firstdialog

seconddialog

B. What differences did you notice between the two samples?

C. What do you think affected your ratings of the two samples?

excellent

good

fair

poor

bad

10

8

6

4

2

0