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Posted by u/mariano54 2 months ago
Launch HN: Issen (YC F24) – Personal AI language tutor
Hey HN, we're Mariano and Anton from ISSEN (https://issen.com), a foreign language voice tutor app that adapts to your interests, goals, and needs.

Demo: https://www.loom.com/share/a78e713d46934857a2dc88aed1bb100d?...

We started this company after struggling to find great tools to practice speaking Japanese and French. Having a tutor can be awesome, but there are downsides: they can be expensive (since you pay by the hour), difficult to schedule, and have a high upfront cost (finding a tutor you like often forces you to cycle through a few that you don’t).

We wanted something that would talk with us — realistically, in full conversations — and actually help us improve. So we built it ourselves. The app relies on a custom voice AI pipeline combining STT (speech-to-text), TTS (text-to-speech), LLMs, long term memory, interruptions, turn-taking, etc. Getting speech-to-text to work well for learners was one of the hardest parts — especially with accents, multi-lingual sentences, and noisy environments. We now combine Gemini Flash, Whisper, Scribe, and GPT-4o-transcribe to minimize errors and keep the conversation flowing.

We didn’t want to focus too much on gamification. In our experience, that leads to users performing well in the app, achieving long streaks and so on, without actually getting fluent in the language you're wanting to learn.

With ISSEN you instantly speak and immerse yourself in the language, which, while not easy, is a much more efficient way to learn.

We combine this with a word bank and SRS flashcards for new words learned in the AI voice chats, which allows very rapid improvement in both vocabulary and speaking skills. We also create custom curriculums for each student based on goals, interests, and preferences, and fully customizable settings like speed, turn taking, formality, etc.

App: https://issen.com (works on web, iOS, Android) Pricing: 20 min free trial, $20–29/month (depending on duration and specific geography)

We’d love your feedback — on the tech, the UX, or what you’d wish from a tool like this. Thanks!

anavat · 2 months ago
Thanks for working on this! Language learning really needs a breakthrough.

Now, I tried the web app and chose to learn Greek as a beginner. And while I had better experience with your app than with ChatGPT or Gemini voice modes, I still got lost 5 minutes in because the AI tutor doesn't seem to have a plan for me, nor does it "see" my struggles. For example, after asking me about a hobby, it gives me a long sentence in Greek about how how it is nice to hike in mountains. Being absolute noob I cannot reply to it, nor even repeat it. And I don't even know what it is expected from me at the moment. A human tutor here would probably repeat a part of the sentence with a translation and ask me to repeat, or would explain something. The AI just sits there waiting for me to make a sound, and when I make it, it goes on on a tangental subject of beach vacations. :)

Again, this is still relatively not bad, and I'm going to give it another try.

drakonka · 2 months ago
I had a similar feeling with Swedish just now. It isn't really much different than conversing with ChatGPT in advanced voice mode - it's up to me to drive the conversation and it all feels quite arbitrary (and I find myself instinctively falling back on topics I know how to talk about, which quite defeats the purpose). I was hoping for a more structured learning plan that strategically expands my comfort zone and skills in a guided way.
mariano54 · 2 months ago
Thanks for the feedback. Yeah we need to improve the beginner experience, it's more tailored towards intermediate/advanced students at the moment.
sotix · 2 months ago
Language Transfer[0] will continue to be a better resource than any AI course. It’s very hard to beat a human that has put in time crafting a logical way to teach a language with the appropriate ramp ups. The Greek course on there is fantastic. And it’s free with zero ads. Best language learning tool I’ve ever used period.

[0]: https://www.languagetransfer.org/

simonbarker87 · 2 months ago
Agree, it was a game changer for me with Spanish. Learning a second language is just plain hard and LT is the closest to “a breakthrough” I think we will get, but it’s still hard and people don’t like that.
candiddevmike · 2 months ago
What's the best way to listen to this on your mobile in a way that will remember your location? SoundCloud app?
frank20022 · 2 months ago
Agreed, languagetransfer is fantastic. Much better than any "AI tutor".
sirodoht · 2 months ago
Funnily enough I said my native language is Greek but then it responded with an error and reset my onboarding guide. Then, I lied that my native language is English, which worked. But now it calls me Anton, rather than the name I said I have!
dbuxton · 2 months ago
I also got Anton. Looks like something's hard coded - or maybe a caching issue?
kevmo314 · 2 months ago
I think this is a pretty big limitation of the architecture (STT->LLM->TTS) they've chosen. The intonation around struggling to speak or difficulty with certain phrases is totally lost when the text is transcribed.
mattbee · 2 months ago
I paid for Memrise to polish up French. The scripted lessons alwere great but it dropped me into an AI conversation assistant that did exactly the same. It forgot the vocab and grammar level that the scripted lessons had taught, and often broke into idiom. I haven't picked it up since.
Nadya · 2 months ago
I'm a Memrise beta member w/ lifetime premium access for my contributions to the site in its early days. I cannot recommend anyone use Memrise for anything nowadays it has been so heavily enshittified. In fact, I recommend against using it in favor of Anki (Memrise's biggest strength over Anki in the early days was the community mnemonics and courses (Anki equivalent "community decks") - none of which really exist in any way today).

I tried following the modern Japanese track on Memrise and was appalled at how bad it is nowadays.

koakuma-chan · 2 months ago
I think the point here is for you to practice (i.e. develop "muscle memory" for speaking), not to learn.
thaumasiotes · 2 months ago
As far as using language goes, those aren't different things.
thinkingtoilet · 2 months ago
>We didn’t want to focus too much on gamification.

Thank you so much for this. Duolingo is literally unbearable because it's so gamified. I'll try it out later. I've seen a few of these apps, can I seamlessly go between my native language and the language I'm trying to learn? If I am trying to learn Hindi, can I ask a question in English in the middle of a conversation?

vjerancrnjak · 2 months ago
The app is optimized on the whole population, not on individual level. They even publish papers on global optimization.

These kinds of learning apps are destined to become mediocre over time.

The learning metric is so easy to capture, the learning content so easy to produce, yet no one has an individualized loop to make learning work well.

For example, I'd press "Training" on Duolingo, and would get nowhere. Same lessons all of the time. Bread and water.

ChadNauseam · 2 months ago
Duolingo is laughably inefficient. I have an app I've made for myself to learn french, and it's amazing how little effort is required to make something 10x better. (I completed the french Duolingo tree and learned essentially nothing so I feel justified in saying that.) If you're learning french, let me know and I'll add you to the app.
mariano54 · 2 months ago
Yes, we've spent a lot of time getting the STT and TTS to work seamlessly in multilingual, it works pretty well!
thinkingtoilet · 2 months ago
I said I would use it and report back. Unfortunately, the experience was not great for me. I told it multiple times I'm a beginner and not speak in full, long sentences in my target language, and it would remember that for one response maybe, then switch right back to full sentences. I had to keep telling it I couldn't understand it and that I'm a beginner. After the 4th or 5th time I gave up.
TypingOutBugs · 2 months ago
Babbel is better than Duolingo!
thinkingtoilet · 2 months ago
Unfortunately, Babbel doesn't have a Hindi course. I wish it did.
itake · 2 months ago
I'm trying to learn vietnamese, but the lessons are really really rough and borderline bad advice.

---

AI: Anh mệt is good if bạn are a man speaking about yourself. You can also say, “Em mệt” if you’re a woman.

this isn't correct. If you are of "older brother" age and are male, you say Anh. Em is for if you are "younger person" (does not matter the gender). Women tend to prefer being called "em" (even if they are older), because women prefer to be identified as younger than their true age... But that doesn't mean you can't call younger men em.

A good tutor would know your age relative to theirs and explain this context.

---

It would say english phrases with a vietnamese accent.

---

It also would give me really complex vietnamese phrases that I am not ready for. when I prompt for an explaination or translation, it would get off track from the original thing we were learning.

---

Way more people in Vietnam (and the globe) speak southern Vietnamese, but the tutors seem to be from north Vietnam.

---

The STT also was very forgiving if I pronounced things incorrectly. Or it would confuse english and vietnamese. I would say, "Phai", but it heard "bye"

---

I was ready to pull out my credit card, but I can't trust it to teach me the right information. I pay $160/mo for Vietnamese tutoring ($20 per class). This would be way cheaper and I don't have to schedule my classes.

mariano54 · 2 months ago
We are really sorry for the subpar experience. We did not test Vietnamese, and it seems like the quality is not sufficient. Thanks for pointing out the issues.
tempodox · 2 months ago
This sounds very much like the kinds of mistakes that LLMs typically make. It's a pity, I would love a good language learning platform.
Velorivox · 2 months ago
A fundamental problem with language learning built around an LLM is that the one thing you can guarantee is that no two people will have a consistent experience, nor is there ever going to be a 100% freedom-from-error. That makes it very hard to predict and therefore market what or how people will learn.

I think this company will end up pivoting into a B2B context before long. Hopefully they will still stick to the mission, but who knows (and I wouldn't fault them if they don't – survival comes first).

true_pk · 2 months ago
Hey, it’s great to see other people learn Vietnamese! And your feedback is on point. I’m still at the beginning and just built a tool to help me learn basic phrases. I will very much appreciate the feedback! https://envn.app
itake · 2 months ago
I haven't figured out what works for me yet when learning Vietnamese, so I'm not really sure yet was advice to give.

Trying out your tool, I'd really like to know if the sound is north or southern Vietnamese. I think your tool is southern vietnamese, but idk.. I personally prefer learning southern, but all the AI TTS tools use the north dialect. Ideally, I'd like a 'pure' southern accent and not a hybrid.

For your tool, You might want to get into the way to address people (Anh, em, ba, co, etc). You seem to just use toi (which I hear vietnamese people using with each other too...) but my understanding is the (Anh/Em/Ba/etc) are more 'intimate' whereas toi is more formal/business like?

One idea I haven't tried too much of yet is making flash cards that teach me a sentence structure, but introduce new vocabulary. Learning a diaspora of phrases works for short 2-3 word ones, but when I try to learn more complex sentences, my brain isn't able to draw the patterns as nothing is connected.

For example, trying to learn "bạn tên là gì" and "nhà vệ sinh ở đâu" (from your website) is harder than learning "Bạn tên là gì?", "Bạn nghề là gì?", "Bạn số điện thoại là gì?"

The other huge challenge I have is feeling like I am making progress. I'm definitely getting better, but its pretty disheartening to study for 40+ hours and still can't pronounce words like Can Tho properly, despite knowing how to read and write.

---

My email is in my profile. Feel free to reach out to me if you have more updates or want to bounce ideas.

iandanforth · 2 months ago
Alright, having tried this with Japanese I can say it's frustrating. As a near complete beginner the tutor kept speaking in Japanese even when I said "sorry I don't understand" repeatedly and then when I asked it to start in English and then gradually transition to Japanese it lasted all of one sentence in English before switching back. I can totally see how this would be useful conversation practice if you've progressed that far, but I'd love to have something for even earlier beginners. Also since many of the models you use are natively multi modal this could readily integrate visual media for discussion and grounding.

Also, for the transcription it would be great to get pure romanji to start with!

antonaf · 2 months ago
Yes, I can understand and empathize with your experience. Quite honestly our current focus is more for B1+ students. That 0 -> 1 / bootstrapping of the language is much better served by traditional material that is less talking / listening-heavy.
55555 · 2 months ago
Unfortunately, I think you will soon learn that the market for advanced language learners is 1/500th the size of the market for beginner learners. But thank you very much and please keep focusing on us.
SkyBelow · 2 months ago
I think I'm around A2 in Japanese and find myself kinda scared by all these talking apps. I don't mind texting, because it gives me time to look up what I don't know and much more time to think about my response, but talking just makes me feel very anxious. Eventually I have to get over the barrier, but it is a barrier to entry and could scare people away.

I do think immersion is generally better, but it is not only harder, an AI app doesn't seem like it could do the right kind of immersion (missing body language, visual cues, seeing the mouth movements, and all sorts of other things one gets from watching a podcast, or even better, in person interaction).

iandanforth · 2 months ago
This is demonstrably false. Natural language acquisition is almost entirely listening and talking. The fastest and most consistently effective way to learn a language is immersion. The reason traditional material doesn't attempt immersive techniques is because it is much much easier to print a static book than it is to produce interactive and adaptive content.

The promise and potential of LLM based language learning apps is that you can cross that gap to full immersion in a way that has never been possible before.

Please be more ambitious.

Deleted Comment

masspro · 2 months ago
I don't think I can trust TTS for language learning. I could be internalizing wrong pronunciation, and I wouldn't know. One time I tried Duolingo for Japanese already knowing a bit. To their credit I assumed it was recorded clips, until it read 'oyogu' as something like 'oyNHYAOgu', like it concatenated two syllable clips that don't go together. If I didn't already know, would I be trying to study and replicate that nonsense? So I don't know if I could trust TTS audio for language study regardless of what kind of tech it is. Sure mistakes can be unlearned over time spent immersing, but at much more effort than just not internalizing them in the first place.

Also Japanese specifically has this meme where it literally is a pitch-accent language but many people say it's not and teaching resources ignore it. E.g. 'ima' means either 'now' or 'living room' depending if syllable #2 is higher or lower. Clearly only applies to some languages, but is another dimension even harder to a learner to know there's a mistake. I have to imagine even other Latin languages probably have reading quirks where this could happen to me.

runarberg · 2 months ago
Also a Japanese learner here—albeit a beginner. As I understand it, the pitch accent is about stress, languages can stress a syllable with length, volume, pitch, etc. Spanish uses vowel length, Icelandic uses volume, English uses a combination of length and volume, and Swedish (just like Japanese) uses pitch. Just like in English if you put the wrong stress on the word it can range anything from sounding foreign to being incomprehensible. (Aside: I always remember trying to say the name of the band Duran Duran to an English speaker, while putting the stress on the first syllable like is normal in Icelandic, but my listener had no idea what I was saying, it took probably 30 attempts before I was corrected with the correct stress).

I think Japanese is somewhat special though for a large number of homonyms (i.e. words that are spelled the same) so speaking with the correct pitch becomes somewhat more important.

glandium · 2 months ago
Somewhat more important, but as someone with decent Japanese who knows about pitch accent but can barely hear the difference in real time, and never actively learned it except for the few well known examples like bridge/chopstick, I don't think it matters all that much. Yes, you'll sound foreign. But you'll be understood nevertheless, in the vast majority of cases.
mariano54 · 2 months ago
Minimax's new model is quite good. We use their voices for some of our Japanese tutors. The pitch accent is almost perfect.

There are incorrect reading or Chinese readings occasionally, but you can tell when that happens due to the furigana being different

yorwba · 2 months ago
If you have the correct furigana, you could even detect when the TTS model picked the wrong reading and regenerate.

But how do you know the furigana are correct? Unless you start out fully human-annotated text, you need some automated procedure to add furigana, which pushes the problem from "TTS AI picked the wrong reading" to "furigana AI picked the wrong reading."

barrell · 2 months ago
Yeah Japanese TTS is a lot harder than it looks. I’m also building a language learning application, and constantly ran into incorrect readings. Eleven labs, eleven labs v3, OpenAI, play.ht, azure, google, Polly — I’ve tried them all. They are all really bad (more than 1/3 the expressions had an error in them somewhere).

It _is_ fixable though. It took me about a week, but I have yet to find a mistaken reading now. This also seems to just be the case with Japanese - most tonal languages seem to have the correct tones (I’m not qualified to comment on how natural the tones sound, but I have yet to find a mismatch like in Japanese)

jamager · 2 months ago
Yes. AI transcription is great, AI translation is OK (depending on language pair), but TTS is still pretty awful for most languages.
vunderba · 2 months ago
The ChatGPT mobile app in hands-free voice conversation mode works quite well for language practice with one important call-out: you have to give it a topic at the beginning otherwise it won't be able to drive the conversation forward and will stick to banal pleasantries.

What I usually do is pick a random blurb in the news and paste the entire thing along with the Reuters link at the beginning and inform ChatGPT that we'll be carrying on language practice specifically over that topic of discussion.

I've used this to carry an hour long foreign language practice in Spanish while walking my husky. Just put the phone in my pocket and go. If you're an intermediate/advanced learner, it's a pretty decent solution.

In fact, you can actually instruct ChatGPT that you are going to speak in your native language, but ChatGPT is only allowed to respond in the target language if you just want to focus on practicing listening comprehension.

I'd be interested in hearing how significantly improved Issen is over this.

mariano54 · 2 months ago
Yeah, agreed, we started with a similar observation. These voice models are getting better quickly.

You do need an app to create a holistic learning experience just for language learning. Customized curriculum, tons of prompting, AI models chosen for transcription accuracy, flashcards/dictionary, etc.

We also support hands free mode, and many other things are customizable like slang, speaking speed, target language usage, etc.

artur_makly · 2 months ago
OMG this app f'n rocks. My convo with my Argentine mujer is soooo fluid and smooth.

I've been living in Buenos Aires for over 18 years now, so my pronunciations and accent is quite good. It's just that I never had the proper early fundamental foundations of grammar ..so I have a bunch of embarrassing holes that need filling -- this app is quite precise when it comes to focusing on those aspects.

Te felicito!

Ps my only nit pick so far is the UX on ios > the Settings modal > when opened there is no clear CTA to close it. Because the click-state of the settings button is 97% the same color as the non-click state.

Solution : 1 - add a close X button to the top right (standard accessibility)

2 - change the click-state Color of the settings button to a reverse color or accent color.

Want more UX tear-downs? Dm me artur at visualsitemaps.com

dbuxton · 2 months ago
For me this is great for practice (I tried Russian). However the big missing piece for all these language learning apps is the lack of support for spotting and correcting errors in your pronunciation - as long as you say the word more or less right, the transcription gives you a pass.

I am very excited for the whole STT/TTS to go away and for us to have models that really "hear" exactly what you said.

Sometimes this is about accent but a lot of the time, the AI won't spot areas where you e.g. fudge a case ending or the stress on a word. Yes, you can get some of that pronunciation right by the AI repeating back with the correct stress or clear case, but you never really get the confidence that you would get from an actual human.

Another product suggestion - turn off transcription (at least for the tutor side of the conversation; I'd suggest both). Personally I find it distracting at best for languages I already speak well and a crutch for those I don't.

Finally, I find it really very hard to enjoy having a random conversation that's not very directed ("What interests you most about artificial intelligence?"). I'd suggest that there are ways of making it more goal focused without being explicitly gamified - maybe something like, here's a position and you have to persuade me (AI debate club!), or something that brings out an actual opinion or relates to a concrete experience ("what's your main goal in your job this year").

Overall though this is the first product I've seen in this space that I might actually use, so well done.

mariano54 · 2 months ago
The persuasion lesson sounds like a great idea, we haven't thought of that. Yeah voice to voice models will be amazing. There is significant progress from openai/gemini, and we plan to use them when they are ready.