The technical measurement of individual parameters in an area as complex as music and song has achieved acceptance only in recent years. However important objective parameters of normal voice development may be, they are especially so when patholo- cal deviations have to be recognised and defined. It is nevertheless also possible to a certain extent to describe different qualities of normal voice development in terms of measurable parameters. Hormonal changes have a considerable influence on the ph- ical and mental development of boys and girls. The extent to which this influence affects...