In sound recording an acetate disc is a reference audio disc used during production of a gramophone record (e.g. an LP record). The acetate disc is created as one of the initial stages of record production and used to determine how a given recording will transfer to disc. Listening to the disc provides a reference and allows various changes can be made to the recording, such as changing overall volume or adjusting bass and treble, to ensure it will transfer to record as well as possible before the master disc, from which the actual records will be reproduced, is created.
An acetate disc is actually usually an aluminium disc coated with nitrocellulose lacquer, most don't contain any acetate at all.