The objective two-signal method of measurement described in Annex I should be used for the determination of radio-frequency protection ratios in frequency-modulation sound broadcasting with transmission standards using a maximum frequency deviation of ±75 kHz and a pre-emphasis of 50 p; the results obtained by this method should be checked by subjective listening tests whenever possible.The objective two-signal method of measurement described in Annex I should be used for the determination of radio-frequency protection ratios in frequency-modulation sound broadcasting with transmission standards using a maximum frequency deviation of ±75 kHz and a pre-emphasis of 50 p; the results obtained by this method should be checked by subjective listening tests whenever possible.The objective two-signal method of measurement described in Annex I should be used for the determination of radio-frequency protection ratios in frequency-modulation sound broadcasting with transmission standards using a maximum frequency deviation of ±75 kHz and a pre-emphasis of 50 p; the results obtained by this method should be checked by subjective listening tests whenever possible.