I like the concept, i think with a few improvements this really could work well, but in the current state, it’s very hard to make out where you are in relation to the enemy. The first rounds i thought my ship was not making any sounds and i did finish with a score of 0, but as i realized it’s the same i could manage to get at last 30, but it felt more like rng / luck hits.
Apart from the fact, that the movement sounds have very low volume, but they are one of the most important sounds in order to know where i am and where i need to move, the player and enemies have the same sounds. So as soon as i hit a button, i have no idea anymore, what is a enemy movement and what is my own. I think you could solve this in two ways, either have different (pitched) sounds for player and enemy, or just pan player left and enemies right. That way i can distinguish where I am in relation to where the enemy is (or maybe even both)
Also, i believe every enemy did only make the sound once he spawned or moved. That makes it also hard to track them, since i would need to remember the exact tone height for every spawning enemy which get’s overwhelming really fast. I think it’s usually a good idea to have a continuous beep sound, for every enemy on the screen, so i can find them again later.
I also missed completely if i was hit or not, i’m not sure the enemy hit sound and player hit sounds are distinct? It felt like at some point it was just game over, but i didn’t even know if I was hit or not. It would be good if the “enemy destroyed” sound and the player hit sound are very different, so i can know what is what.
Lastly the bullets, i’m not ever sure there is a sound for enemy bullets, maybe just a shoot sound, but i have no ideas where these bullets are in relation to my ship. I think you could easily give the bullets also a pitched sound, that matches the enemy position, and then (if you use the pan left and right approach) let them start right and pan them to the left as the bullet flies, so i have the possibility of dodging them.
I think conceptually this works, you just need to clean up the sounds and then this could be a classic acrcade like audio only shmup. (And please add a cool arcade like game over sound as well :P)