Makaton (see Makaton Language Programme on Wikipedia and the Makaton Charity) combines spoken language with gestures, i.e. the signs or symbols do not replace but supplement spoken language. It was not designed for deaf people but for people who cannot communicate effectively using only speech. (You can find short tutorials and examples on YouTube.)
The signs come from or are based on the sign language of the country where Makaton is used, so there is German Makaton, French Makaton, etc.
The Makaton Charity on the UK has a webpage about relevant research.
On a more technical note: while many sign languages used by deaf communities have ISO 639-3 language codes for use in computing, the Makaton sign languages do not yet have such codes. When I contacted the Makaton Charity in the UK about this in 2014, they were not interested in registering such codes.