Likely relates to MC-3735. This is one of several things mentioned under MC-94956, however should not be resolved as a duplicate as having several closely-related issues under one ticket is frowned upon these days.

The bug

Creepers emit a hissing sound when preparing to explode. This is of course intentional, however they will still play this sound to completion even if killed. This is very commonly observed in regular PvE combat. This sound continuing to play is unhelpful as the creeper is no longer in a state of being able to explode after death.

How to reproduce

1. Weaken a creeper such that it can be easily dispatched in one hit, e.g. a known amount of attacks from a given weapon, or via poison
2. Kill the creeper from close range such that it has the opportunity to prepare to explode
3. Note that, despite being dead, the sound continues to play in full

Expected results

The sound would either stop immediately or rapidly fade out after the creeper's health reaches 0.

Actual results

The sound keeps playing despite there not being any explosion for it to lead up to.

Notes

This same issue was previously reported under MC-1602 in late 2012. That ticket was later resolved as a duplicate of MC-4921, an issue that was fixed soon after, but this creeper-related issue still persists ten years later, indicating it wasn't actually a duplicate of that. I'd recommend that MC-1602 be re-resolved as a duplicate of this ticket for accuracy's sake (or alternatively, this ticket to be resolved as a duplicate of it, it to be reopened and me to be assigned its new owner, although this option is more laborious).