Damaten

Damaten 「黙聴」, or dama for short, is a closed tenpai hand that has not called riichi. Typically, a dama hand will have a yaku without needing to riichi; otherwise, menzen tsumo (or another circumstantial yaku) would be needed to win. An older term yamiten 「闇聴」 refers to the same thing.

Usage

Main article: Riichi strategy

There are many reasons to dama. In most cases, it occurs when the extra points from riichi do not matter:

When the call for riichi wouldn't increase the hand's value by itself. For example, a haneman is scored with a 6-7 han hand. If a player had a 6 han hand, the +1 han from riichi would not increase the score. While declaring riichi could still with a tsumo, ippatsu, and/or ura dora, these aren't reliable,.
When the hand is valuable. Because players will often defend against a riichi hand, declaring riichi will usually lower your hand's win rate. With a guaranteed mangan or higher, the increased win rate from dama may outweigh riichi's score bonus. Plus, once mangan is reached, each han afterwards has reduced value.
When winning at all is the only thing that matters. When far in the lead, dama can be used to increase win rate (thus, ending the game faster). If the game is in all last, and winning with riichi wouldn't improve placement (even with ippatsu ron), dama can also be considered.
When the hand can improve. Riichi locks your hand in, preventing you from upgrading the wait or gaining yaku. If your hand has many upgrades, you may wish to dama.
When the hand is poor. If a hand would be riichi-only with a bad wait, committing to riichi may not be worthwhile. Staying dama gives a chance to tsumo, and enables folding if another player reaches tenpai.

That being said, dama should not be overused. Riichi is a guaranteed +1 han, and on average provides +1.5 han. Since each han below 4000 points roughly doubles score, riichi offers a large score boost. See riichi strategy for more details on the decision to riichi or dama.

Game examples

黙聴

Damaten in Japanese Wikipedia

Usage

Multiple instances where damaten was employed.