ForewordScopeNormative referencesTerms and definitionsMeasurement procedureGeneralMeasurement instrumentsMerging the basic spectraEvaluationGeneral informationWidth, Δf, of the critical bandDetermination of prominent tonesGeneral informationDetermination of the mean narrow-band level, L, of the masking noise in the critical bandDetermination of the tone level L of a tone in a critical bandDistinctness of a toneDetermination of the critical band level, L, of the masking noiseMasking indexDetermination of the audibility, ΔLDetermination of the decisive audibility, ΔL, of a narrow-band spectrumDetermination of the mean audibility, ΔL, of a number of spectraCalculation of the uncertainty of the audibility, ΔLRecommendations on the presentation of resultsMeasurementAcoustic environmentInstruments for measurement, recording and evaluationAcoustic dataWindow effect and Picket fence effect (informative)Resolving power of the human ear at frequencies below 1 000 Hz and geometric position of the critical bands – corner frequencies (informative)Masking, masking threshold, masking index (informative)Iterative method for the determination of the audibility, ∆L (informative)GeneralDetailed diagram 1Detailed diagram 2Detailed diagram 3Example for the determination of audibility (informative)Bibliography