Which form is the correct causative-passive 聞く?

Question

There is an exercise in スピードマスターN4 to put verbs in the causative-passive form:

つまらない話を（聞いて）、眠くなった。

The answer key says the correct form should be 聞かされて. While, for example, JLPT Sensei lists it as 聞かせられる which is literally passive form of the causative 聞かせる.

Which form would be correct and why? When should one be preferred over the other?

Answer 1

Both are correct.

Godan verbs can take two causative forms as mentioned in Wikipedia

「～せる」を「～す」と表すこともあるが、それは、五段活用のみであって、上一段活用・下一段活用・カ行変格活用・サ行変格活用では表さない。

Thus 聞かす・聞かせる are both legitimate causative forms of 聞く, and adding passive, they become

• 聞かす＋れる　→　聞かされる
• 聞かせる＋られる　→　聞かせられる

(I'm not sure 聞かす is categorized as godan or サ変 but either way it takes れる. It conjugates: 聞かさ(ない)/聞かし(ます)/聞かす/聞かす(とき)/聞かせれ(ば)/聞かせろ.)

As for preference, my feeling is that there is none, but perhaps せられる is harder to pronounce and used less frequently (by unconscious choice).

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Similarly: 読まされる・読ませられる, 書かされる・書かせられる, 立たされる・立たせられる are all possible causative-passive forms.