Prominent Discrete Tone Procedures for IT Equiment - Reconstruction of Annex D of ECMA-74 for Ease of Use

For evaluation of tonal components of IT equipment noise, Annex D of ECMA-74 states two parallel metrics: tone-to-noise ratio AND prominence ratio. These metrics are very similar each other, but not equal. In addition, both methods are based on use of FFT spectrum of acoustical noise of interest. For expressing the amplitude of FFT spectrum, there are two alternative ways: sound pressure level in dB (re 20 ?Pa) and mean-square sound pressure in pascal-squared. Eventually, each user of the annex has to select one specific way out of four parallel methods. In this paper, the issues, from view point of users, are summarized, and the proposed solutions are present.