I am completely deaf in one ear, and would like to be able to force mono-output (system-wide) when using headphones. How can I do this? It seems that this is a useful accessibility feature.
There is no easy or quick solution to set the audio output to mono. But you could try the link below. It is from the ubuntu forum because elementary freya is based on ubuntu 14.04
Mix stereo to mono (Ask Ubuntu)
The first answer sounds promising.
Please give us a feedback if this solution works. Thanks