Yeah, lots of room sound in the hello clip. Not sure why you included the singing clip.
So, as others might have said the problem areas for any room that size is going to be the bass freqs. Your vocal test does not have much energy in the problem area, so it really isn't useful.
In a commercial studios, they have two rooms, a 'live' room and a 'mixing' room. The rooms are treated differently for the different functions they serve. For home recording types like us, we usually get one room to work with and so we have to make compromises. We either make it a better live room or a better mixing room and we decide how the acoustic treatment will reach those goals. I have always advised to make the room better for mixing because you can artificially add in room response to a vocal track or acoustic guitar or whatever.
For a mixing room, you want to eliminate all reflections, even those you can't hear. Your hello test reveals a reflection in the high mids - low highs (800hz - 2khz) which tells me the bass freqs (500hz and below) are worse, but those are the ones you can't hear.
So, you need bass traps as suggested. Not foam. DIY bass traps don't have to be expensive and you can make them free-standing. You just have to be willing to do some work and be a little creative.
The bass traps will absorb the problem freqs as well as the ones you hear. The ones you hear can be added back in with reverb and delays, etc. But when you go to mix, you don't want the standing waves, or peaks and valleys in your room's audio response. Small cubical rooms need lots of bass trapping.