Fit for duty?
The Team
2
Zoe
Bevis
Matthew
Blyth
Hannah
Semeraro
PhD Students
Supervisory Team
Dr Daniel
Rowan
Dr Rachel
van Besouw
Dr Ben
Lineton
Dr Adrian
Allsopp
Funded by
3
Current measure of AFFD
4
Overview
(1) Identifying mission critical auditory tasks (MCATs)
(2) Introducing a new speech communication fitness-for-duty
test
(3) Next steps
(1) Identifying mission
critical auditory tasks
(MCATs)
Method
Focus groups
80 infantry personnel
Range of ranks
Active service experience
Qualitative analysis
7
(1) Identifying MCATs
Stage 1: Exploration of auditory tasks
Stage 2: Determination of MCATs
Results
Seventeen auditory tasks
Speech communication (8)
e.g. hearing grid references
Sound localisation (6)
e.g. locating a talker
Sound interpretation (3)
e.g. determining talker
identity
Bevis ZB, Semeraro HS, et al.
Fit for the frontline? A focus group exploration
of auditory tasks carried out by infantry and combat support personnel.
Method
Questionnaire
87 infantry personnel
Quantitative analysis
Likert scale ratings for
1. Who performs the task
2. Consequences of poor
performance on the task
3. Frequency of task
8
(1) Identifying MCATs
Stage 1: Exploration of auditory tasks
Stage 2: Determination of MCATs
Results 8 MCATs
Sound Localisation
- Locating a small arms firing point
Speech Communication
- Accurately hearing commands in a
casualty situation
- Accurately hearing grid references
- Accurately hearing directions on patrol
- Accurately hearing directions in a
vehicle
- Accurately hearing fire control orders
- Accurately hearing ‘stop’ commands
- Accurately hearing the briefing before a
foot patrol
(2) Introducing a new
speech communication
fitness for duty test
• Review of existing speech tests
– Thoroughly reviewed long list of existing speech tests
– Particularly in terms of face validity
•
Gathered opinions of military subject-matter experts
-
All had experience issuing commands
-
Speech test stimuli rated on relevance to command structure
10
(2) Introducing new speech test
11
(2) Introducing new speech test
Which test?
Chosen test
Equalising stimuli
Adaptive procedure
THE COORDINATE RESPONSE MEASURE
– Re-recorded e.g. using NATO call signs with a British accent
– Removed disyllabic number seven
– Increased number of target words
12
(2) Introducing new speech test
Which test?
Chosen test
Equalising stimuli
Adaptive procedure
-16 -14 -12 -10 -8 -6 -4 -2 0 0 20 40 60 80 100 Callsigns (1) SNR (dB) P ro p o rt io n C o rr e c t (% ) -16 -14 -12 -10 -8 -6 -4 -2 0 0 20 40 60 80 100 Callsigns (2) SNR (dB) P ro p o rt io n C o rr e c t (% ) -16 -14 -12 -10 -8 -6 -4 -2 0 0 20 40 60 80 100 Colours (1) SNR (dB) P ro p o rt io n C o rr e c t (% ) -16 -14 -12 -10 -8 -6 -4 -2 0 0 20 40 60 80 100 Colours (2) SNR (dB) P ro p o rt io n C o rr e c t (% ) -16 -14 -12 -10 -8 -6 -4 -2 0 0 20 40 60 80 100 Numbers (1) SNR (dB) P ro p o rt io n C o rr e c t (% ) -16 -14 -12 -10 -8 -6 -4 -2 0 0 20 40 60 80 100 Numbers (2) SNR (dB) P ro p o rt io n C o rr e c t (% )
First:
equalised
RMS level
Fir
st
: eq
ua
li
sed
R
M
S l
evel
-16 -14 -12 -10 -8 -6 -4 -2 0 0 20 40 60 80 100 Callsigns (1) SNR (dB) P ro p o rt io n C o rr e c t (% ) -16 -14 -12 -10 -8 -6 -4 -2 0 0 20 40 60 80 100 Callsigns (2) SNR (dB) P ro p o rt io n C o rr e c t (% ) -16 -14 -12 -10 -8 -6 -4 -2 0 0 20 40 60 80 100 Colours (1) SNR (dB) P ro p o rt io n C o rr e c t (% ) -16 -14 -12 -10 -8 -6 -4 -2 0 0 20 40 60 80 100 Colours (2) SNR (dB) P ro p o rt io n C o rr e c t (% ) -16 -14 -12 -10 -8 -6 -4 -2 0 0 20 40 60 80 100 Numbers (1) SNR (dB) P ro p o rt io n C o rr e c t (% ) -16 -14 -12 -10 -8 -6 -4 -2 0 0 20 40 60 80 100 Numbers (2) SNR (dB) P ro p o rt io n C o rr e c t (% )Second:
equalised
speech
intelligibility
Sec
on
d
: eq
ua
li
sed
sp
eec
h
int
elli
gib
il
it
y
FOXTROT
BRAVO
• Questions:
– How precise is the CRM as a speech-in-noise test?
– What is the best CRM scoring method?
– What is the concurrent validity of CRM when compared to the
Triple-Digit-Test (TDT)?
• Method:
– Normal hearing (n=30) and hearing impaired (n=22) listeners
– Three test conditions: CRM with two scoring methods and TDT
– Tw0-down-one-up adaptive procedure, speech-spectrum noise
– Repeated measures (normal hearing 4 repeats, hearing
impaired 2 repeats)
13
(2) Introducing new speech test
14
(2) Introducing new speech test
Which test?
Chosen test
Equalising stimuli
Adaptive procedure
Test condition
Typical measurement error
(95% confidence interval,
dB)
Correlation with
TDT (Pearson’s
𝒓
)
Normal
hearing
Hearing
impaired
Normal hearing &
hearing impaired
CRM (callsigns on)
2.1
1.8
0.78
CRM (callsigns off)
1.9
2.5
0.68
15
(3) Next step: external
validation of CRM fitness for
duty test
16
(3) Next step
TONIGHT’S AMBUSH WILL BE AT GRID 758 671
MOVE INTO THE WOOD LINE AND GO FIRM
AT THE FORK IN THE TRACK GO LEFT
I REQUIRE THE MEDIC AT MY LOCATION NOW
•
External validation:
comparing performance on the CRM with
performance on
Laboratory simulation of MCATs
•
80 commands recorded using KEMAR
wearing a military radio
•
Processed through hearing loss simulator
simulated operational tasks
