Yes, absolutely. Kirtan is above all a devotional practice. Therefore, the most important factor is the inner attitude (bhava), and not necessarily a beautiful voice. To sing out of tune with an open heart full of compassion is far better than a chant executed in tune but coldly and with no heart in it. With practice, you’ll see that the voice is getting more melodious and you will sing more and more in tune. This is the magic of kirtan.