Any change in pronunciation over time which destroys the contrast between two or more segments. A simple example is the loss of contrast in many English accents between ʍ (as in which, what, when etc.) and w. In this case, the merger results in the simple loss of a sound leaving only one of the original original members of the contrasting pair. Mergers can also result in the appearance of a new sound. An example of this is the merging of the vowels ɪ e ʌ into ɜː in many English accents. This merger took place immediately before a word-final or pre-consonantal r. Compare Scottish English herd and word (herd wʌrd) where the merger has not taken place with GB hɜːd wɜːd where it has.