Alien Baltan makes sounds like a human laughter.
It’s unknown if the sounds are their words or they are actually laughing.
The sounds themselves are sound effects diverted from the ones Matango made in the 1963 Toho movie “Matango” directed by Ishiro Honda and (SFX part) Eiji Tsuburaya.
As the movie was screened when I was one year old, I saw it on television as a kid.
Since Ultra Series were already broadcast, I was surprised to hear Matango, mushroom-like monsters humans transformed into, make sounds like Baltan.
But I knew it was the other way round in later years.
It’s likely the laughter-like sounds were adopted to make them associated with a dramatic laughter bad guys often made in movies or TV dramas in those days.
Those villains of the time laugh loudly a lot.
For instance, there is a TV SFX hero drama titled “Shonen (boy) Jet” that was broadcast from 1959 to 1962 including its sequel and gained popularity.
The story is about Shonen Jet, young (too young?) detective, fighting with Shane, buddy dog, against villains.
Black Devil is one of its regular villains.
When I enjoyed watching the series on cable television, he was always laughing while making mischief.
His loud and cheerful laughter make viewers feel warm and happy.
He laughs that much. 😀
He’s a bad guy hard to hate!