BAA MAGAZINE SUMMER 2017 DRAFT 4

FEATURE
Development of the Spatial
Speech Assessment
This study was submitted in partial fulfilment of the requirements for the MSc degree in Advanced
Audiology (UCL Ear Institute)
BHAVISHA PARMAR
Senior Audiologist
RESEARCH SUPERVISORS
DR J BIZLEY
UCL Ear Institute
DR D V VICKERS
UCL Speech, Hearing and Phonetic Sciences
Can we test a hearing aid user’s
spatial hearing and speech
discrimination at the same time?
Introduction
Current clinical tests of localisation and
speech understanding do not reflect
the difficulties faced when listening
in the real world with competing
speakers and other distractions.
There are currently no gold standard
tests of localisation for clinical practice
(Volck et al 2015) and assessments
of both localisation and speech
discrimination tests are not routinely
carried out for adult hearing aid users.
However, there is a need to be able to
assess hearing abilities, including the
ability to identify and locate speech, in
a way that reflects listening in the real
world.
With this requirement in mind,
a simultaneous assessment of
localisation and speech discrimination
was developed by Bizley et al (2015)
and used to test normal hearing
participants. During this assessment,
the participant was seated in the
centre of the anechoic chamber and
surrounded by eighteen speakers
arranged at 150 intervals. The
following sixteen monosyllabic words
from the Chear Auditory Perception
Test (CAPT) (Marriage et al. 2011)
were spoken, in pairs, by a single
female in the presence of multi-talker
babble:
A target word was presented
Table 1: Monosyllabic words from the Chear Auditory Perception test
(CAPT) (Marriage et al.2001) used in the simultaneous assessment of
relative localisation and speech discrimination developed by Bizley et al
(2015).
followed by a reference word from
an adjacent speaker. A touch-screen
tablet was used to allow participants
to report both words and the location
of the target word in relation to the
reference word. Word identification
and word localisation percentage
scores were recorded across speaker
location. Bizley et al (2015) found that
normal hearing listeners had the best
relative localisation scores were for
words coming from the front of space
when compared to those presented
in the periphery. This pattern reflects
the superior availability of binaural
localisation cues in frontal space. The
inverse result was found for word
identification with higher recognition
scores being obtained in laterally
rather than in frontal space. This effect
is likely due to the effects of the head
shadow effect enhancing the signalto-noise
ratio at the near-ear giving a
mono-aural advantage.
Method
The current study focussed on using
the spatial speech assessment
technique to test the performance
of hearing aids in a group of five
adults with bilateral moderate to
severe sensorineural hearing loss. All
five participants were experienced
hearing aid users, but for the
purposes of this study they were
fitted with Phonak Sky Q hearing aids
and given a period of six weeks to
allow for acclimatisation before the
assessments took place.
The hearing aids were programmed
with three different microphone
programs – omnidirectional, directional
and the binaural beamformer. All
participants were given a hearing
aid microphone diary, adapted from
Cord et al (2002) to assess the
subjective benefit of each microphone
programme in different situations and
asked to spend roughly equivalent
amounts of time listening with each.
After the six week trial, each
participant returned to perform the
spatial speech assessment. Before
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