Doing stuff like this in the 8-bit era was never particularly hard. The difficulty was doing this and then anything else, because you basically need the entire CPU just for audio synthesis. For games, there was a very real trade-off between calculating video, game state, and sound, and sound often took the back seat.
It's also why everything looked and sounded better on 8-bit computers that had hardware support for graphic sprites or sound generation, even if they had a less powerful CPU. And it's the untold story behind why 16-bit graphics looked so much better: it wasn't about the CPU as much as it was about having a dedicated video card / chipset with its own memory, a sound card that handled polyphonic sound and MIDI synthesis, etc.
I have a memory of a Spectrum game playing some sort of synthesised speech through the speaker that seemed incredibly ahead of its time. I believe the game was called iBall. And the sample said something like “Fight iBall!” Have I misremembered that? Was this a fever dream?
The 128k version of Nodes of Yesod had some speech, albeit I think it was just the name of the game. My older brother told me a kid in his class got paid big bucks - like, I dunno, £50 or something? - for coding it. Almost certainly bollocks.
Although tbf apparently that's done via the AY sound chip of the 128k, which is a lot easier than through the on/off beeper of the 48k since the AY can do digitized audio via CPU-driven volume modulation.
There was a music editor I remember getting on a late Your Sinclair edition cover tape which displayed proper music staves and gave you 4-note chord output. Blew my mind a bit at the time.
Due to all the constraints the ZX Spectrum is a fantastic system for recreational programming; too bad I missed the latest Spectrum Next batch last year.
It's also why everything looked and sounded better on 8-bit computers that had hardware support for graphic sprites or sound generation, even if they had a less powerful CPU. And it's the untold story behind why 16-bit graphics looked so much better: it wasn't about the CPU as much as it was about having a dedicated video card / chipset with its own memory, a sound card that handled polyphonic sound and MIDI synthesis, etc.
https://news.ycombinator.com/item?id=49895486
There's also a phone with YM2149
For high quality speech, you could get the Currah μSpeech! https://en.wikipedia.org/wiki/Currah#Currah_%CE%BCSpeech_for...
I swear there was one symbol it pronounced "flea bleep".
(And there was a "Get ready!" which I didn't remember)
https://www.youtube.com/watch?v=hRW9vW3_M3o&t=8
https://youtu.be/yjrbcLm78I8?si=GMIqDdL31hq4ik72&t=87
Although tbf apparently that's done via the AY sound chip of the 128k, which is a lot easier than through the on/off beeper of the 48k since the AY can do digitized audio via CPU-driven volume modulation.
https://spectrumgamesuk.com/index.php?game=Meteor-Storm
I think it said "Meteor Alert!" or something similar, though the quality was terrible.
https://www.youtube.com/watch?v=u-D24A_N4d4