A great way to develop your musical ear is to practice rhythmic dictation. Rhythmic dictation is when a rhythm or sound is presented, and you test your listening by writing down the rhythm that you hear in musical notation. This can be done is many ways:
The Clap Test. You have a friend clap a rhythm and you clap it back to them. Compare the two sounds. Did they sound alike? Did they sound similar? Write down the rhythmn in musical notation.
Dictate music. Listen to a musician and write down the rhythmn of one specific instrument.
Listen to nature. Go to a place where you can hear natural sound and listen to the sounds of animals. For example, write down the rhythm of a woodpecker pecking.
Try out Chop Monster. Chop Monster is a jazz language book and CD set that is designed to teach young players how to improvise, using call and response. The CD will play a short lick, and the student would play the pattern back. After developing an ear, the student may be able to write down the rhythms and notes they hear in musical notation.