Recommendation ITU-T H.870 (03/2022) Guidelines for safe listening devices/systems Summary History FOREWORD Table of Contents Introduction 1 Scope 2 References 3 Definitions 3.1 Terms defined elsewhere 3.2 Terms defined in this Recommendation 4 Abbreviations and acronyms 5 Conventions 6 Safe listening: Introduction 6.1 Background 6.2 Personal audio system 6.2.1 Consideration of headphones and earphones 6.2.2 Note on individuality 6.2.3 Guidance on measurement 7 Damage risk criteria 7.1 Operational modes 7.2 Uncertainty in dose estimate 8 Measurement methods 8.1 Dosimetry 8.1.1 Main related standards 8.1.2 Definition of dose in the context of acoustic dosimetry 8.1.3 Testing of dosimeter functionality 9 Sensitivity range and frequency response of headphones 10 Profiles 11 Health communication 11.1 Purpose of including health communication as part of the standards for safe listening personal audio systems 11.2 Key recommendations for communication as part of standards for safe listening devices 11.2.1 Device interface user information 11.2.1.1 Personal usage information 11.2.1.2 Messages 11.2.2 General information 11.2.3 Information through means other than the device itself: 11.2.3.1 User manual 11.2.3.2 Packaging 11.2.3.3 Website and advertising 12 Ambient noise control 12.1 Passive attenuation of the background noise 12.2 Active noise reduction of background noise 12.3 Benefits of noise-isolating earphones 12.4 Safety concerns associated with noise-isolating earphones 13 Volume control 13.1 Volume limiting 13.2 Password-protected volume control 14 Guidance on ancillary concerns Appendix I Status report Appendix II Dose estimation functionality for implementation in a personal audio system II.1 Introduction II.2 Main related standards II.3 Definition of dose in the context of acoustic dosimetry II.4 Weighting of different frequencies II.5 Signal capture point in a personal audio system (PAS) II.6 Handling of left and right channels II.7 Dosimeter implementation example II.8 Handling of computational complexity II.9 Handling of dose over days and weeks II.10 Case of unknown headphone characteristics II.11 Alternative audio signal capture point II.13 Uncertainties Appendix III European Standard EN 71-1 for toys Appendix IV "Music" versus "noise" Appendix V On stapedius muscle reflex Appendix VI Consideration of recovery phase Appendix VII Example of health communication VII.1 Recommendations to develop warnings and cues for action messages for device interfaces VII.2 Suggested flow (an example) of information as part of standards for safe listening devices VII.3 Example of how the information on listening parameters can be conveyed to the user VII.3.1 Information on use of weekly allowance VII.3.2 Information on how the user has used the allowance on any day VII.3.3 Listening time VII.4 Warnings and cues for actions VII.4.1 Examples of warnings and cues based on weekly use VII.4.2 Examples of messages based on daily use VII.4.3 Examples of messages with positive versus negative frame; and emotional versus rational appeal Appendix VIII Mechanism of hearing and impact of impact of sound VIII.1 Sound and waves VIII.2 Mechanism of hearing and hearing loss VIII.3 Measurement of sound energy VIII.3.1 Pressure VIII.3.2 Decibels VIII.3.2.2 dB SPL VIII.3.2.3 dBA VIII.3.2.4 dBFS VIII.3.2.5 dBHL VIII.4 Equal energy principle Bibliography <\pre>