To see how advanced the ear pieces are, we compared them to two translation tools on the market, Google Translate’s conversation mode and the hand-held CM Translator ($117 retail) from Cheetah Mobile. A preproduction model of the Ambassador ($150 retail) was tested at company headquarters in Brooklyn, while the WT2 Plus earbuds ($230 retail), were used by two multilingual students at the University of Colorado Boulder. The upshot: Google Translate and the CM Translator would be fine for ordering a beer or asking the location of a museum, but both would fall short if trying to engage with the person sitting next to you on the train.

“I thought it was really cool that you could talk in one language and a few seconds later it would come out in a different language,” Maya Singh, a freshman who speaks English, Russian and Spanish, said of the WT2 Plus earbuds.

The WT2 Plus and the Ambassador each offer unique advantages. In its conversation mode, the Ambassador allows one user to interrupt another, as is done in real life, and translates simultaneously to both. The WT2 Plus requires the speakers to take turns, but simultaneously transcribes the conversation, and later this year it should be able to translate English, Chinese, Japanese, Korean and Russian while offline, said Kazaf Ye, head of marketing for Timekettle, in an interview from company headquarters in Shenzhen, China.

“Efficiency is a key element in deciding whether one person wants to continue talking to the other person,” Mr. Ye said. “If it is too much trouble or if I have to wait too long then I will not want to talk with him, I’d rather just speak to someone in my language.”

Andrew Ochoa, the chief executive officer of Waverly Labs, said the ultimate goal in translation devices would be an earpiece that works offline, in real time, and can translate everything you hear.

If that device is ever developed, “I can drop you off in the middle of Tokyo … and it will translate everything in your proximity,” Mr. Ochoa said.

While we’re not there yet, translation has taken a quantum leap forward in the past few years because neural machine translation can process phrases, not just words.