An oceanographic research vessel deploys an underwater acoustic array consisting of $k$ independent hydrophones to record cetacean vocalisations. The continuous analogue sound received by each hydrophone is digitised as illustrated below:

Draw on this

State an algebraic expression, using the variables defined below, to calculate the total raw data size in bits of an uncompressed recording, assuming no metadata or headers are included:

• $k$: the number of hydrophones (channels)
• $R$: the sampling rate (in Hz)
• $D$: the bit depth (sample resolution in bits)
• $T$: the duration of the recording (in seconds)