Background:

Hyperacusis is defined as oversensitivity to some everyday sounds (lowered threshold of discomfort to sounds). Children may complain that their ears hurt when exposed to some sounds, typically high pitched or unexpected loud noises. For some children, this can be extremely distressing and can have a significant effect on behaviour. Phonophobia is defined as a fear of sound and in the most extreme cases, the lowest level of the particular sound can trigger what appears to be a disproportionate reaction, with physical symptoms of anxiety, tantrums and avoidant behaviour.

Certain groups of patients are known to be at greater risk of experiencing hyperacusis. It is a common and often disabling condition in Williams Syndrome and has been associated with abnormal cochlear function (Gothelf et al, 2006). It is the commonest sensory perceptual abnormality in children who are on the Autistic Spectrum, with prevalence ranging from 15-100% (Gomes et al, 2008). In these children there is little evidence of peripheral audiological abnormality (Gravel et al, 2006). Research has shown that there are more likely to be central causes for the unusual reactions to auditory stimuli in these children (Khalfa et al, 2001; Orekhova et al, 2008; Jones et al, 2009).

A recent study of 506 children between the ages of 5 and 12 years has used a questionnaire to assess the prevalence of hyperacusis in typically developing children (Coelho et al, 2007a). This identified that hyperacusis was reported by 3.2% of children. The same population was also asked questions related to tinnitus (Coelho et al, 2007b). 37% of children reported hearing a noise inside their head and 17% described it as annoying. Risk factors for experiencing tinnitus included young age, hearing loss and hyperacusis.

The ALSPAC data offers a unique opportunity to establish the prevalence of hyperacusis in a large population of children and to evaluate whether there are any significant associations with early life history, including detailed hearing data.

Research aims and objectives:

1. To determine the prevalence of hyperacusis in the ALSPAC cohort at age 11 years

2. To investigate risk factors for hyperacusis, specifically to examine:

a) Child factors: gender, prematurity, birthweight, migraine, special educational needs (ASD, ADHD & other conditions), meningitis & encephalitis, head injury requiring hospitalisation

b) Auditory function: hearing and acoustic reflex thresholds, current and historical otitis media with effusion, tinnitus

c) Socioeconomic factors: socioeconomic status, maternal education and housing tenure

Methods:

At the age 11 Focus clinic, approximately 7000 children were asked about sensitivity to sound, known as hyperacusis. Pilot analysis showed that approximately 3 % of these children reported hyperacusis of which 60% had experienced it for at least a year. Children were also asked whether they experienced noises in their ears (tinnitus) and pilot analysis showed that children with hyperacusis were more likely to report tinnitus than children without hyperacusis.

We intend to explore the characteristics of children reporting hyperacusis to determine possible risk factors for this condition. We will use univariate and multivariate logistic regression to determine whether those with hyperacusis have common factors in their early medical history (see objective 2a). We will also determine whether there are any differences in pure tone and acoustic reflex thresholds. Finally, we will examine socioeconomic factors.