McLeod and Crowe (2018) looked at 15 speech acquisition studies to determine the average age children learn to produce English consonants.
"zh" is the sound made in measure.
Voiced "th" is the sound made in that.
Voiceless "th" is the sound made in bath
Difficulty pronouncing age expected sounds is a possible sign of a speech sound disorder, which has been linked to reading difficulties. If your child is difficult to understand or is frustrated when not understood, we can help!