My current radio does not have a build in DSP (Digital Signal Processor) to clean up the audio... after researching on the Internet I decided to purchase one of these : -
I have to say it's not a magic device as some reviewers would have you believe, but it definitely does a VERY good job of cleaning up audio signals and reducing background noise/static on all modes, which is nothing but good news for your ears, the only caveat is that it can take a second or 2 for the filter to start working on recieved audio.
Apart from the obvious improved listening experience the advantage this device gives is with noisy week signals and can make the difference between understanding the other operator and not, of course there is a threshhold where no amount of processing can make you hear what simply is not there.
Which brings me onto something else I've noticed when using this filter, when monitoring a frequency for a long time listening to processed static, I swear ocassionally I can hear 'something' like a voice, when I know for a fact there is nothing there. I think what is happening is the filter is trying to process the static noise as 'speach' and my brain is also to trying to process this processed noise trying to recognise speach and so I hear a 'voice' by some random chance, took me a while to figure out I was not going mad or am I?