The vocal range suitable for children aged 4 to 5 years old is the mid-range (C4 to C5).

Medium Range (C4 to C5) This is the most common part of a young child's vocal range and includes the tones that most young children can sing. It mainly includes notes ranging from low C (C4) to high C (C5).

The vocal range of children aged four to five can be expressed in Chinese as the range of sounds. At this age, young children's voices gradually develop and are able to produce both higher and lower pitches. They can imitate and make different sounds, including the sounds of various animals, vehicles, sounds of nature, etc.

Children can also demonstrate their vocal range through activities such as singing and reading aloud, and gradually learn to produce more types and levels of sounds. At this stage, the development of vocal range is of great significance to children's language ability and musical expression ability.

The language development characteristics of 4 to 5-year-old children include: expanded vocabulary, enhanced grammar and sentence structure, gradually clear pronunciation, enhanced language understanding, and improved expression ability

1. Vocabulary Expansion of vocabulary: At this stage, children's vocabulary begins to grow rapidly. They are able to understand and use an increasing number of words and begin to learn and express more specific concepts and vocabulary.

2. Grammar and sentence structure enhancement: Young children begin to use more complex grammatical structures, such as using compound sentences, using different tenses of verbs, etc. They can form longer sentences and begin to express more complex ideas.

3. Pronunciation gradually becomes clearer: At this stage, children's pronunciation ability is improved, and it is easier for them to pronounce various phonemes and words clearly. However, there may still be some pronunciation errors that require patient guidance and correction by adults.

4. Enhanced language understanding: young children can better understand and follow complex instructions. They begin to be able to understand and answer various questions, grasp context and semantic meaning, and understand the main lines of conversations and stories.

5. Improved expression ability: young children can cope with more complex thinking and emotional expressions. They begin to use appropriate words and sentences to express their needs, feelings, and ideas.