Jason Flynn, age 13, of Carson City, Nev., for his question:

WHY DO SOME PEOPLE LISP?

Lisping is a speech defect. Persons who lisp have difficulty pronouncing sibilant or hissing sounds, such as S or Z. Many children lisp when they first start to speak. During normal speech development, most children master the hissing sounds long before school age.

Sometimes, however, a child's speech development may be delayed. Various things can cause such delays. Among these may be loss of hearing and defects of mouth structures, particularly the tongue, teeth and palate.

Almost all children lisp when they lose their primary front teeth. Improper speech habits by parents, such as using baby talk, may also  delay a child's speech development.

When lisping results from mouth defects, the defects must be corrected before completely normal speech can be obtained. Speech therapists, who are specially trained to treat speech disorders, teach persons who lisp to speak correctly.

Some who lisp substitute "th" for the s sound: I thee my thither. Some may omit the S altogether: I  ee my  i ter. Still others may distort the S into a whistling sound.