Using a dual male to female 3.5mm joiner, one signal is overpowering the other

[TheBasementNerd]

Ok so I have one speaker, a bluetooth receiver, and my desktop. I decided a fun setup would be to be able to use my bluetooth receiver and desktop with one speaker without having to worry about wire interchange. The system works great, except I just discovered a flaw when booting up Dark Souls while my girlfriend was using the bluetooth. There was no sound from my game. It turns out that for some reason, the signal from the bluetooth (and it's also the same if I plug the phone straight in) overrides the signal from the other end. It quiets it like when using Google Maps and playing music on your phone, and the Maps speaks over the music. I have no idea how or why, and the issue was the same even after I changed the plugs around, so it's something with the phone signal. I haven't tried any other devices so far, but how on earth can this be happening? Every input is all stereo, in and out

TL;DR: Dual male 3.5mm to female 3.5mm has one signal overridden by the other signal

 

[Alabalcho]

The proper way of mixing two audio signals is to use proper device called "audio mixer". It seems the speaker you are using is not designed with multiple simultaneous sources in mind. So, you have either live with what you have (and adusting the phone volume so that it does not overtake you game volume), or use the proper tool for the job.

Search your favorite store for "audio mixer" or "multi-channel headphones amplifier", something like this