Human speech is a complex sound, so you’ll need a little more practice to begin with. Start by using your hearing aid at home with someone whose voice you know well.
Remember that communicating combines listening with concentration and visual clues. Pay attention to facial expressions and gestures, and you’ll understand more.
Hearing aids, like ears, pick up sound best from the front. So, place yourself in front of people when they speak. If you know them well enough, ask them to speak in a normal tone and without covering their mouth with their hands.