Transverse audio frequency into phonetic alphabetical speech synthesizer


I require your help regarding a problem I’m encountering. (Let me know if wrong category and I’ll try to repost elsewhere and delete question)

I know that this is a study somewhere, but I’ve forgotten.
I’m wondering if anyone remembers seeing the study that uses tones as voice.
There is a tone library for the arduino that allows the programmer to set the tone from different Hertz. The only time I used it was in the Let’s Start Coding basic kit.
I’m wondering if someone remembers the study that changes time+tone=letter and letter+=word.
Hardware concerned:
(Possibly - Let’s Start Coding Basic Kit)
Software concerned:
(Possibly - Arduino)
Troubleshooting steps already taken:
Additional information:
This might be the wrong place to post topic - which I apologize in advance.
I wouldn’t have posted this if I could find a link to the answer…so I’m sorry, but I felt like it should be common knowledge and it’s not…
Thank you so much in advance for your help!

It would be this in the video, but I think you try and send multiple tones to the buzzer at once to produce a robot voice.

[Another annoying example by a lazy IC company. They obviously can’t own sound. So it sounds to me like most companies don’t want you to know how to do this because most companies are pulling their proprietary hardware for propriety software.

Someone’s TTS freeware; weird.