This type of drum is the most authentic, as they were traditionally made and used by shamans. You can not change the tension of the skin, the sound depends on the humidity. With very dry weather you can use a little spray of water to slacken the skin a bit, with care(!). Or you can use the fire or a hairdryer to dry the skin a bit. But also with care, as the heat can still continu to have an effect of the tightness of the skin. If you overdo this often, the skin will need more and more heat to come back to the right tension.
Some examples of different styles