What is Speech Intelligibility? Intelligibility refers to the clarity of speech, or how much of someone’s speech a listener can understand. Parents often worry when their child is not understood by others. It is common for young children to make mistakes as they learn to say words. There is also a lot of variability in speech development between children. However, as your child learns to talk, their ability to be understood by others should steadily increase. So, how can you tell if your child’s speech intelligibility is on track or falling behind? Dr. Peter Flipsen, Jr. has developed a simple formula to use as a guide to evaluate a child’s speech clarity in conversational speech with unfamiliar listeners (Flipsen, 2006).