BS 6840-5:1990

National foreword
Committees responsible
1. Scope
2. Object
Section One - General
3. Conditions
3.1 General conditions
3.2 Conditions for the measurement
4. Test signals
4.1 Sinusoidal signal
4.2 Broadband noise signal
4.3 Narrow band noise signal
5. Acoustical environment
5.1 Free-field conditions
5.2 Half-space free-field conditions
5.3 Diffuse sound field conditions
6. Unwanted acoustical and electrical noise
7. Positioning of loudspeaker and measuring
      microphone
7.1 Measuring distance under free-field and half space
      free-field conditions
7.2 Positioning of loudspeaker in diffuse field
      conditions
8. Measuring equipment
9. Accuracy of acoustical measurement
10. Mounting of loudspeakers
10.1 Mounting and acoustic loading of drive units
10.2 Mounting and acoustic loading of a loudspeaker
      system
11. Standard baffle
12. Preconditioning
Section Two - Characteristics to be specified and the
relevant methods of measurement
13. Type description
13.1 Loudspeaker drive units
13.2 Loudspeaker system
14. Marking of terminals and controls
15. Reference plane, reference point and reference axis
15.1 Reference plane
15.2 Reference point
15.3 Reference axis
16. Impedance and derivative characteristics
16.1 Rated impedance
16.2 Impedance curve
16.3 Total Q-factor (Qt)
16.4 Equivalent air volume of a loudspeaker drive unit
      compliance
17. Input voltage
17.1 Short term maximum input voltage
17.2 Long term maximum input voltage
17.3 Rated sinusoidal voltage
17.4 Rated noise voltage
18. Input electrical power
18.1 Short term maximum power
18.2 Long term maximum power
18.3 Rated sinusoidal power
18.4 Rated noise power
19. Frequency characteristics
19.1 Rated frequency range
19.2 Resonance frequency
19.3 Tuning frequency of a bass reflex or passive
      radiator loudspeaker system
20. Sound pressure under free-field and half space
      free-field conditions
20.1 Sound pressure in a stated frequency band
20.2 Sound pressure level in a stated frequency band
20.3 Characteristic sensitivity in a stated frequency
      band
20.4 Characteristic sensitivity level in a stated
      frequency band
20.5 Mean sound pressure in a stated frequency band
20.6 Mean sound pressure level in a stated frequency
      band
21. Response under free-field and half space free-
      field conditions
21.1 Frequency response
21.2 Effective frequency range
21.3 Transfer function
22. Output power (acoustic power)
22.1 Acoustic power in a frequency band
22.2 Mean acoustic power in a frequency band
22.3 Efficiency in a frequency band
22.4 Mean efficiency in a frequency band
23. Directional characteristics
23.1 Directional response pattern
23.2 Radiation angle
23.3 Directivity index
24. Amplitude non-linearity
24.1 Introduction
24.2 Total harmonic distortion
24.3 Harmonic distortion of the nth order
24.4 Characteristic harmonic distortion
24.5 Total noise distortion
24.6 Noise distortion of the nth order
24.7 Characteristic noise distortion
24.8 Modulation distortion of the nth order
24.9 Characteristics modulation distortion of the
      nth order
24.10 Difference frequency distortion
24.11 Noise intermodulation distortion
Section Three - Other characteristics and classification
25. Rated ambient conditions
26. Interfering stray field
27. Physical characteristics
27.1 Dimensions
27.2 Weight
27.3 Cable assemblies
28. Design data
29. Classification of the characteristics to be
      specified
Table
1. Characteristics to be specified and classification
Figures
1. Standard baffle, dimensions (Clause 11)
2. Standard baffle with chamfer (Clause 11)
3. Standard baffle with sub-baffle (Clause 11)
4. Restricting and clipping network (see 17.4.2)

Defines the characteristics to be specified and the relevant methods of measurement for sound system loudspeakers, treated as entirely passive elements, using sinusoidal or specified noise signals. Loudspeakers with built-in amplifiers are not included.