adding ーすませ to the end of a noun


The second line of the song Umi no Koe/海の声 says:

> 風の声に 耳すませ  
>  (kaze no koe ni mimisumase)

In this sentence, what does it mean when すませ is added at the end of 耳/ear.

The full verse is this:

> 空の声が 聴きたくて  
>  風の声に **_耳すませ_**  
>  海の声が 知りたくて  
>  君の声を 探してる

Thank you!




Here, 澄ませ【すませ】 is a verb. The object marker を after 耳 has been omitted.
(Dropping を makes this part 5 morae long and rhyme with the other lines.)

済ませ is the masu-stem (aka pre-masu form, 連用形) of the causative form of the
godan (aka consonant-stem or U-) intransitive verb 澄む.

  * [**澄む**](https://dictionary.goo.ne.jp/jn/120157/meaning/m0u/%E6%BE%84%E3%82%80/): an intransitive godan verb, "to be/become clean/clear/transparent/keen"
  * **澄ませる** : the causative form of 澄む, "to make something clean/clear/keen". see the conjugation rule [here](https://www.wasabi-jpn.com/japanese-grammar/japanese-causative-form/).
  * **耳を澄ませる** : (literally "to make the ears keen") "to listen carefully"
  * **耳を澄ませ** : the masu-stem (pre-masu form) of 耳を澄ませる

The masu-stem can be used to continue a sentence just like the te-form. (See:
[て versus combining-form for joining
clauses](https://japanese.stackexchange.com/q/23789/5010) ) Therefore, the
line means "I listen carefully to the voice of wind (, and ...)"

* * *

Well, in fact, 澄ませる is an uncommon form, because we have a standalone
transitive version of 澄む, namely 澄ます, which is also a godan verb.

  * [**澄ます**](https://dictionary.goo.ne.jp/jn/119957/meaning/m0u/): a transitive godan verb, "to make something clean/clear/keen"
  * **耳を澄ます** : (literally "to make the ears keen") "to listen carefully"
  * **耳を澄まし** : the masu-stem of 耳を澄ます

I think 耳を澄ます is worth memorizing as an idiom, and is far more common than
耳を澄ませる. But they mean the same thing, anyway.

All in all, the following four forms will work quite similarly in this
context.

  * **耳を澄まして** : the te-form of 澄ます
  * **耳を澄まし** : the masu-stem of 澄ます
  * **耳を澄ませて** : the te-form of the causative form of 澄む (relatively uncommon)
  * **耳を澄ませ** : the masu-stem of the causative form of 澄む (least common among the four)

