Alamak normal je lah, jangan risau! Anak saya dulu pun umur 1 tahun lebih baru start sebut "mama" dengan jelas, sebelum tu dia pun sibuk dengan bunyi sendiri macam "kah kah" jugak hehe. A few of my mum friends say their kids were like that too, some babies asyik explore bunyi dulu before they connect it to people, so jangan khatir yang slow or apa, every baby punya timeline sendiri. Lagi pun dia dah cuba communicate dengan "kah kah" tu, so cognitive-wise dia dah on track, cuma linguistic development dia yang belum catch up lagi. Keep talking to him, respond to his "kah kah" sounds, and I'm sure dalam few weeks atau months tu dia dah pandai sebut "mama" and "papa" dengan proper!