Wind instruments use a column of vibrating air to produce a sound. By changing the length of the column of air the player can adjust the pitch of the sound. The longer the column the lower the pitch. Some instruments require a reed to start producing the vibrations others the player makes a raspberry sound into a mouthpiece. Recorders and flutes just require air to pass into a mouthpiece to produce a vibrating column of air.
Where are these instruments being played?
Is anyone else nearby? How can you tell?
How are they making their sounds?
Describe how the vibrations were produced and then travelled to the microphone.