Backing Vocals can provide support to a Learner's performance in a number of ways.

They can support the harmony of the the Learner's performance, as well as the correct note they are to sing and provide an element of strength to their voice and audibility of the lyrics.

Even on tracks when there is only a very basic backing vocal (i.e a simple ooh...aah), though it may not support the voice, it will assist the Learner with their counting and aid them in identifying where they are in the track. As a result they could subsequently speed up, or slow down in order to stay in time. It can also provide further support to achieve any accuracy in the rhythm. 

Backing Vocals can also risk distracting a Learner while they are singing. If they are out of time and backing vocals come, it could throw the Learner off even further or cause them to worry and panic.

In order to ensure that every Learner is able to perform with the same conditions and to the best of their ability, all backing vocals are prohibited when taking LAMDA Musical Theatre examinations.