A developmental perspective on localisation of speech in babble

Brook, Rhiannon Elizabeth (2020) A developmental perspective on localisation of speech in babble. PhD thesis, University of Nottingham.

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The ability to localise speech in background sound is important for listening in real world environments. It is known that children can successfully localise in quiet at an adult-like level by 6 years of age, and children aged 7 to 16 years can localise in broadband noise at a similar level to adults, but are poorer than adults when listening in the presence of speech babble. This may compromise their listening abilities in real world environments, which could in turn affect their language acquisition and educational outcomes. This potential impact means it is important to know more about how children localise in babble.

This thesis includes the first studies to accurately quantify the developmental time course of minimum audible angle (MAA) and localisation of speech in babble abilities of participants aged 6-29 years. The relationships between localisation, detection and identification of speech in babble are also examined.

Firstly, in a series of experiments with 68 participants aged 6-29 years, the time course of typical development of localisation of speech in six talker babble was mapped using a five choice localisation task. It was found that performance could be fitted using an exponential function which had a time constant of 6.6 years. Using a variety of analytical methods, adult-like performance was found to occur in the early to mid-teenage years.

Next, the relationships between detection, identification and localisation of speech in babble were investigated. This was thought to be important because if a listener had difficulty with localisation it would be helpful to know if they could detect and/or localise the stimulus. This was initially done in 40 participants aged 10-28 years, finding that participants performed best in identification, followed by localisation and detection which were similar. The study was then repeated with 17 participants aged 18-30 years, using more challenging SNRs and an additional localisation task. There were smaller differences between tasks but generally performance was highest on the detection task. Overall, it was found that even if a listener could detect and/or identify a word in babble, they could not necessarily localise it.

Finally, the developmental time course of MAA of speech in babble was mapped in 50 participants aged 6-21 years. Mean performance over all conditions could be fitted with an exponential function with a time constant of 5.8 years and using a variety of analytical methods, adult-like performance occurred in the early to mid-teenage years.

These are the first studies to have found the developmental time courses of localisation and MAA in babble in typically developing and normally hearing children age 6 years and older. These developmental time courses can be used as benchmarks to compare with populations who may have difficulties with spatial hearing in background sound, such as children with hearing impairments or with auditory processing disorder. These studies have also demonstrated the relationships between detection, identification and localisation of speech in babble in adults and children.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Akeroyd, Michael A.
Kitterick, Pádraig T.
Barry, Johanna G.
Brimijoin, W. Owen
Keywords: Localisation of speech; Spatial hearing; Hearing development; Auditory perception
Subjects: W Medicine and related subjects (NLM Classification) > WV Otolaryngology
Faculties/Schools: UK Campuses > Faculty of Medicine and Health Sciences > School of Medicine
Item ID: 60521
Depositing User: Brook, Rhiannon
Date Deposited: 17 Jul 2020 04:40
Last Modified: 17 Jul 2020 04:40
URI: https://eprints.nottingham.ac.uk/id/eprint/60521

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