
True Mono sound, when coming from a television is simply both Left and Right stereo soundtracks mixed together. Nothing fancy.
If you have tried slightly pulling out the headphones socket to achieve “Mono” you are really only getting one channel of information – right or left – in either case you will have effectively removed a little of the other channels background effects/music
In the stereo mix, centralised sounds – such as speech is usually mixed - are shared between right and left channels and are “in phase” so that, for the listener who listens in stereo – as long as they are equidistant from both left and right speakers - psycho acoustically, the speech appears to be coming from the centre.
However, for the hard of hearing it is often more easily noticed that what you have really are two streams of sound, intermixed with different background sounds.
Couple this with the modern techniques of embedding Left + Right + Surround information in the stereo tracks, things can become difficult for those with less than perfect hearing.
Of course those who lose parts of their hearing differ in just what they lose and so it is difficult to be absolute about how to assist. Certainly one of the commonest methods to aid communication is to SHOUT! - In other words simply increase the volume :o)
This method will not work for everybody.
As daft as it may seem Alan may find that using a Dolby prologic system of some kind might be of help.
Why? Because Dolby surround processing will separates the five encoded channels and thus the centre channel volume can be controlled separately. Alan may find that thus he can find a balance that is more acceptable to his ears. In the most extreme of cases, one could even remove the speakers from right, left and both rear speakers – this should effectively remove the vast majority of background- music, effects and all - though I wouldn’t advise this as it is not intended to be used this way!
If Alan wants to share his listening with others, there are Dolby processors available specifically for headphones, and while they generally are not as successful as speakers for separation of sounds, they can be quite effective.
Mike