Birds in Royal Botanic Garden making loud beeping sound

I heard loud 'beeping' or 'whistle' type of noise from a kind of small birds (see enclosed photo) in Royal Botanic Garden, Melbourne. They hang around in the big trees by the swamp/lake. Their chest is mustard colour and the bead is orange. They also chirping like normal birds but when they make this 'beeping' noise, it's really loud, is almost like an electronic sound. Anyone can tell me what this bird is? Thank you.