What do the Hunger of Hadar whispering and slurping sounds do?

Question

Hunger of Hadar (DnDBeyond paywalled link to PHB) has this audio effect:

You open a gateway to the dark between the stars, a region infested with unknown horrors. A 20-foot-radius sphere of blackness and bitter cold appears, centered on a point with range and lasting for the duration. This void is filled with a cacophony of soft whispers and slurping noises that can be heard up to 30 feet away.

What mechanical game effect should these sounds have? I could see a DM ruling they might give advantage on some Intimidation check, or prevent hearing the movement of an unseen creature. But RAW, is that pure fluff text with no practical impact, or is it indeed intended that the DM somehow takes the effect into account, and if so, how?

Related: I asked a separate question about radius of the sounds (30' from the center point, or 30' from the sphere).

Answer 1

The only game effect of the noises is to be heard up to 30 feet.

The complete description of the spell says (emphasis mine):

You open a gateway to the dark between the stars, a region infested with unknown horrors. A 20-foot-radius sphere of blackness and bitter cold appears, centered on a point with range and lasting for the duration. This void is filled with a cacophony of soft whispers and slurping noises that can be heard up to 30 feet away. No light, magical or otherwise, can illuminate the area, and creatures fully within the area are blinded.

The void creates a warp in the fabric of space, and the area is difficult terrain. Any creature that starts its turn in the area takes 2d6 cold damage. Any creature that ends its turn in the area must succeed on a Dexterity saving throw or take 2d6 acid damage as milky, otherworldly tentacles rub against it.

By RAW, the only effects (in term of game mechanics) that the spell does are the bolded ones. There is only one sentence related to the noises, and it specifies that they can be heard up to 30 feet away: if there were some other consequences related to these noises, the description would have reported them.

The sole game mechanic that I see is related to a deaf or blind\$^\dagger\$ character: in the former case, they can't hear anything and, depending on your table's ruling and description of this spell, they may mistake the obscured area produced by Hunger of Hadar for a "simple" Darkness spell. A blind character cannot see the spherical area of blackness, but they may hear the hideous noises and hence have an hint of some kind of danger.

Nothing prevents you from adopting some house rule.

A gaming table may decide to add some other consequences related to these noises: the final decision is entirely up to the DM.

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\$^\dagger\$ Credits to Erik who pointed out in the comments this condition and its consequences.

Answer 2

To make a spell do more than what its description states is to houserule it into being stronger than intended

The spell's description tells you the entirety of what it does. If it didn't, we would be sitting here all day asking without end "But what if spell X secretly has effect Y that the designers never mentioned?" In this case, the spell blinds and deals damage and creates an area of darkness. There is also a cacophony of noise, but the spell never mentions this specifically doing anything like granting disadvantage or deafening creatured. If the designers intended for the spell to have a mechanical effect beyond blinding and dealing damage, they would have mentioned such an effect. To add an effect is thus to make the spell strictly stronger than was intended.

I personally would not consider hunger of hadar to be a weak spell and as such, do not believe it needs to be made stronger through a houserule about its cacophony of noises.

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Sidenote: Some spells are poorly written and ambiguous, some spells are just plain bad. And in these cases houserules to either consistently rule or to improve a spell are, of course, welcome, if not just needed. But hunger of hadar is not such a case, there simply is no mechanical text about the cacophony of noise and so it has no mechanical impact (other than the fact that it can be heard).