He heard the faintest splash, and was not sure whether it was inside or out.
With only a faint splash, it sank beneath the surface and dropped quickly out of sight.
It sailed toward the deep end of the pool, landing with a faint splash.
That faint splash from some distance off to the right, for instance.
A faint splash from below told of his hitting the water.
There was a faint splash as they hit the water below.
There was another faint splash as he spoke, vindicating him.
A faint splash made me look toward the stream.
After a second, there was a faint splash down below.
After a long time there came a faint splash.