A prospective study of 337 children was carried out during a 3-month period. The purpose of the study was to evaluate the importance of indoor environmental factors in homes and day-care institutions for the incidence of middle ear effusion (MEE). The indoor environmental factors measured in institutions were carbon dioxide, temperature, and relative humidity. Conditions in the homes were assessed by a questionnaire. Middle ear effusion was measured by tympanometry. No relationship was found between indoor environmental factors and MEE, with the exception of parental smoking at home, which increased the frequency of MEE in children.

The relationship between vestibular and cochlear function in stapedectomy was investigated in 722 patients (925 ears). There were no differences in hearing between patients with and without pre-operative complaints of vertigo. Post-operatively patients with long lasting vertigo obtained equally good hearing results as the others. The direction of spontaneous nystagmus post-operatively in relation to the operated ear was of no prognostic significance regarding short term hearing results. However, at follow-up an average of 15 years after the operation, hearing was somewhat poorer in those having spontaneous nystagmus towards the operated ear. At follow-up 17% had an abnormal caloric test.

To assess the influence of housing upon the middle ear status in young children in the form of secretory otitis media (SOM), 210 children not looked after in kindergarten or municipal day-care were investigated. Tympanometry was performed 6 times at 2-week intervals, and the parents filled in a questionnaire concerning housing conditions. In addition to the number of times the children had suffered from SOM, we evaluated long-lasting cases, and the frequency of common colds. Age affected all 3 parameters and sex 1, the boys having a larger number of long-lasting episodes. As to housing factors, the type of housing was of importance, children living in flats being most apt to get SOM, and children on farms least, but this difference disappeared after a regression analysis. Both major and minor airing resulted in fewer cases of SOM than did average airing. Children with a history of allergy (but not of allergic rhinitis) caught colds more often than others.

The long-term results of 925 stapedectomies were analysed after a mean follow-up period of 15 years. Patients who had the operation before the age of 30 were analysed separately. The entire group deteriorated by an average of 0.91 dB/year at 500–2000 Hz, while the under-30 group deteriorated by 0.67 dB/year. There were but slight differences in the conductive component, considering frequencies and age. The perceptive loss'year was not far from that in a normal population.

To assess the incidence of secretory otitis media in children minded at home we examined 210 children not attending kindergarten or municipal day care. Of these children 117 were minded exclusively at home or in private day care with up to 2 children. Tympanometry was carried out 6 times at 2-week intervals. Secretory otitis media (SOM) of more than 3 months' duration was found in 17% of the one-year-olds and in 6% of the total series. In the age range 1-5 years the incidence was from 0.35 to 0.19/child/month, and the mean for the total group was 0.26/child/month.