The aim of the investigation was to study if dysfunctions associated to the cochlea or its regulatory system can be found,
and possibly explain hearing problems in subjects with normal or near-normal audiograms. The design was a prospective
study of subjects recruited from the general population. The included subjects were persons with auditory problems who
had normal, or near-normal, pure tone hearing thresholds, who could be included in one of three subgroups: teachers,
Education; people working with music, Music; and people with moderate or negligible noise exposure, Other. A fourth group
included people with poorer pure tone hearing thresholds and a history of severe occupational noise, Industry. Ntotal = 193.
The following hearing tests were used: 2 pure tone audiometry with Be´ke´sy technique, 2 transient evoked otoacoustic
emissions and distortion product otoacoustic emissions, without and with contralateral noise; 2 psychoacoustical
modulation transfer function, 2 forward masking, 2 speech recognition in noise, 2 tinnitus matching. A
questionnaire about occupations, noise exposure, stress/anxiety, muscular problems, medication, and heredity, was
addressed to the participants. Forward masking results were significantly worse for Education and Industry than for the other
groups, possibly associated to the inner hair cell area. Forward masking results were significantly correlated to louder
matched tinnitus. For many subjects speech recognition in noise, left ear, did not increase in a normal way when the
listening level was increased. Subjects hypersensitive to loud sound had significantly better speech recognition in noise at
the lower test level than subjects not hypersensitive. Self-reported stress/anxiety was similar for all groups. In conclusion,
hearing dysfunctions were found in subjects with tinnitus and other auditory problems, combined with normal or nearnormal
pure tone thresholds. The teachers, mostly regarded as a group exposed to noise below risk levels, had dysfunctions
almost identical to those of the more exposed Industry group