The age by which 90% of consonants are produced correctly more often than not is known as the...

• A. Age of mastery
• B. Median age of acquisition
• C. Age of customary production
• D. Normal limit of acquisition

Answer: (A)

In this area of speech development, mastery is tied to reliability across contexts. The 90% threshold is used to mark that a child has truly learned a consonant—producing it correctly in most contexts, not just in a few isolated words. When a child reaches this level, it signals stable, consistent production rather than burst-like or accidental success.

So, the age by which 90% of consonants are produced correctly more often than not is called the age of mastery because it reflects that reliable, widespread ability to produce the sounds. The median age of acquisition would describe when about half of children can produce a sound, which is a lower, less stringent benchmark. The age of customary production points to what is typical rather than reliably mastered across contexts, and the normal limit of acquisition refers to the latest age by which sounds should be acquired, not the high-reliability threshold implied by 90% mastery.