Speech processors.

A speech processor may give improvement on AM and SSB CB systems (illegal in the UK), but you will still need to be wary of incredible claims of massive gains. Any compression or clipping will result in your voice being distorted, more compression or clipping means more distortion. It is only worth the compromise if you regularly use an AM or SSB CB for long distance conversations.

Speech processors are not appropriate for FM CB.
There are many reasons, requiring a technical understanding. However, here are some basic reasons why they should not be used for FM CB:
  * Designed for AM and SSB CB.
  * Claimed talk power does not apply to FM.
  * Claims of double your power do not apply to FM.
  * FM sound level not dependent upon signal level.
  * Not enough space between CB channels.
  * May distort your voice.
  * May interfere with other channels.
You may hear claims that broadcast stations use speech processing. While this may be true, broadcast bands are much better than CB. FM CB does not have the bandwidth that the broadcast stations are allowed - one FM broadcast station takes the same space as 30 CB channels. To do what they do, you will need to use up 30 CB channels with one conversation.