In order to play the tones
you must connect it to a hardware or software synthesizer
like Timidity or FluidSynth.
~~~~
timidity -A300 -iA -B4,4
~~~~

Then start the midimory game and connect the game to the synthesizer:
~~~~
midimory --connect-to TiMidity
~~~~

or alternatively:
~~~~
midimory &
aconnect Midimory TiMidity
~~~~