Johan Peter Holtsmark (13 February 1894 – 10 December 1975) was a Norwegian physicist, who studied spectral line broadening and electron scattering. In 1929, while at the Norwegian Institute of Technology, Holtsmark established acoustics research laboratories, focusing on architectural acoustics and sound insulation. Holtsmark was also a consultant for the Norwegian Broadcasting Corporation (NRK) throughout the 1930s.