Perception of Indexical Cues in Kids and Adults

A cochlear implant (CI) is a prosthetic device that partially restores the
hearing of profoundly deaf individuals. However, the speech signal that is
delivered via the device contains spectro-temporal degradations. As a
consequence, CI users have difficulties with recognizing and distinguishing the
voices of speakers, but the size of this deficiency is currently not fully
known. The main focus of this research is on the perception of voice
characteristics that are mainly determined by fundamental frequency (F0),
related to the glottal pulse rate of the vocal chords, and vocal tract length
(VTL), related to the size of the speaker. Voice characteristics are crucial
for speech communication. They deliver essential information that can be used
in noisy environments to identify the speaker*s voice and to segregate speech
from noise and other speech streams. Understanding speech in noise is
particularly challenging for CI users. Since most speech communication in
everyday life occurs in background noise, the impaired perception of voice
characteristics can considerably and negatively affect the quality of life of
CI users.

Earlier research from our research group has demonstrated that the impaired
perception of voice characteristics in adult CI users leads to abnormal
patterns of vocal gender categorization and emotion recognition (Fuller et. al,
2014; Gilbers et al., 2015). The current study will follow up on these studies
by investigating whether the perception of voice characteristics is also
impaired in children with CIs and how this relates to their general perception
of speech-related indexical cues, speech, and language development, an
important matter for the overall healthy development of deaf children who use a
CI (Szagun, 2001; Geers, Davidson, Uchanski, & Nicholas, 2013).

The main objective of this study is to investigate the developmental trajectory
of the perception of voice characteristics in children and how it relates to
the recognition of gender, emotions, and linguistic processing in CI children,
in comparison to control groups of NH children, and NH adults.

The study consists of a questionnaire concerning the language, hearing, and
demographics of participants, behavioural experiments and eye-tracking
experiments on the perception of voice characteristics, speech perception and
linguistic processing.

There are no known risks or benefits associated with participation. All tests
are non-invasive and consist of simple tasks, such as listening to a recorded
speech sample, and making a judgement about the voice or meaning of this
sample. The test duration and frequency will be adjusted to accommodate the age
and attention span of participants. To further reduce potential fatigue,
adequate breaks will be built into the experiment and will also be given on
request of the participant.