5 month old weird noises???

Has anyone's 5 month old started making a new noise that sounds like they're losing their voice? My son woke up this morning and I swear it sounded like he was losing his voice and I panicked. But since I have heard him making his normal sounds with a normal voice. Then sometimes he does this weird thing and it sounds like he is losing his voice. Just a new sound he discovered? No other symptoms besides the normal mucous crap from reflux. It's like hes try to whisper or something?