A large-scale and PCR-referenced vocal audio dataset for COVID-19 by Budd, J, Baker, K, Karoune, E, Coppock, H, Patel, S, Payne, R, Tendero Cañadas, A, Titcomb, A, Hurley, D, Egglestone, S, Butler, L, Mellor, J, Nicholson, G, Kiskin, I, Koutra, V, Jersakova, R, McKendry, RA, Diggle, P, Richardson, S, Schuller, BW, Gilmour, S, Pigoli, D, Roberts, S, Packham, J, Holmes, C