Just a bit of information on ghasts: For some reason, ghast sound drop off over distance is very low. This means ghasts will likely sound the same or similar when going at survival speeds (walking, sprinting, flying with an elytra, or more related). The vanilla resource pack's sound.json file set all ghasts sounds to 600.0 volume, but this does not determine how loud the ghast actually is. It instead determines the distance where the sound will be completely cut off, not lowering the actual drop off at all. The equation for this is the following:

volume * 16 = sound distance

Anyone within that radius will have sounds play internally, no matter if the sound drop off permits it or not. However, that number for ghasts is way too high anyway. If my calculations are correct, that would mean that ghast sounds only cut off when the player is 9600 blocks away. To confirm this, running the command /summon ghast ~ ~-5000 ~ will still play ghast sounds. At this distance however, it's kind of hard to hear, but the fact that someone can hear it is likely not intended by Mojang.