This is the 595th most frequent Hindi word.
ऊ
The Hindi word "ऊ" is a vowel and denotes the long sound of "u" as in "tool."
Here, 'ऊँचे स्वर' refers to 'high voice' or 'high pitch'. The word 'ऊँचा' is used to describe the pitch.
वह ऊँचे स्वर में गाना गा रहा है।
He is singing in a high pitch.
In this sentence, 'ऊँचाई' represents 'altitude'. The usage indicates a high position in the air.
कुछ पक्षी ऊँचाई पर उड़ रहे हैं।
Some birds are flying at a high altitude.
Here, 'ऊँचाई' (unchai) derives from 'ऊँचा', meaning 'high'. It describes a characteristic of the tree.