Difference between pure tone and speech audiometer

Speech audiometry was performed on 15 children with secretory otitis media pre-and post-operatively and the findings compared with the pre-and post-operative pure tone audiograms. The results showed that in 30 per cent of cases pre-operatively the speech audiogram suggested a significantly worse hearing ability than that suggested by the pure tone audiogram (PTA). Where a PTA gives a borderline threshold disproportionate parental concern should be taken seriously as the hearing ability may well be worse than the PTA suggests.

which

what is a measurement of the earth’s history divided into time periods?

> fossil record <

sedimentary rock

> geologic time scale <

radioactive elements