GB/T 4959-2026Methods of measurement for the sound reinforcement characteristics of auditoria (English PDF)

4.1 Environment

4.1.1 Building Decoration Prior to the measurement, the hall's architectural decoration was already completed, meaning that the seating, doors and windows, curtains, lighting fixtures, dimming equipment, and air conditioning system, etc., were installed according to the original specifications. The building design requires that the installation be completed and the hall be in use or ready for use.

4.1.2 Conditions of the sound control room The voice control room should meet the following requirements.

a) The equipment in the sound control room has been installed and is ready for use;

b) The power supply and grounding of the sound reinforcement system equipment meet the design requirements.

4.2 Public address system The sound reinforcement system should meet the following requirements.

a) Before the measurement, the sound reinforcement equipment was installed in the hall according to the design requirements and was ready for use;

b) Adjust the sound reinforcement system to ensure it is in normal working order;

c) During measurement, the digital signal processor in the sound reinforcement system is adjusted according to functional requirements.

Note. "Functional requirements" refers to the system's gain, signal distribution, equalization, compression, limiting, frequency division, feedback suppression, delay, noise reduction, filtering, and other functions. The specific requirements vary depending on the hall's layout. The actual functions need to be set by the designer and adjusted in the digital signal processor to make them in the best design and use state.

4.3 Signal-to-noise ratio The signal-to-noise ratio should meet the following requirements.

a) During measurement, the sound pressure level at each measurement point in the hall must be at least 15 dB higher than the total noise level of the hall;

b) The signal-to-noise ratio during reverberation time and regeneration reverberation time measurements shall not be less than 35 dB;

c) The signal-to-noise ratio should not be less than 45dB when measuring the acoustic energy ratio in the early and late stages.

4.4 Measurement Site The measurement site must meet the following requirements.

4.5.1 Requirements for the layout of measurement points

4.5.1.1 Measurement point height The measurement point is 1.2m above the ground (reverberation time and regeneration reverberation time are measured from 1.2m to 1.6m).

4.5.1.2 Selection of Measurement Point Area The area selected for measurement points must meet the following requirements.

a) All measurement points should be at least 1.5m away from the wall.

b) For halls with balconies, the measurement points should include the balconies area.

c) For venues with a stage or stage for sound reinforcement, the measurement points should also include the stage area or stage area, but the measurement results should be recorded separately. deal with.

d) If the hall is axially symmetrical, the measurement point can be selected within the seating area on one side of the center line (including the vicinity of the center line).

e) For large venues (such as large stadiums), if the plan is fully symmetrical both longitudinally and transversely, only 1/4 of the area needs to be measured; however, the measurement points should include the area itself. Representativeness of each seating area in the audience area.

f) At least half of the venue area should be measured. The venue measurement data should be recorded and processed separately, and not averaged with the spectator seating measurement data.

4.5.2 Number of measurement points selected The number of measurement points selected is shown in Table 1.

5.17 Test sound source

5.17.1 Motorized loudspeaker sound source The electric loudspeaker sound source should meet the following requirements.

a) Frequency response. 50Hz~10kHz;

b) The difference between two adjacent 1/3 octave band sound power levels should not exceed 3 dB;

c) Sound power level. The sound power level in all 1/3 octave bands should be greater than 70 dB;

d) Sound power output stability. less than ±0.5dB;

e) Directivity index. less than 9dB.

5.17.2 Pulse Sound Source A pulse sound source with stable performance that meets certain duration and waveform requirements, such as a spark sound generator.

5.17.3 Pulse Signal Generator An instrument or device that can generate pulse characteristic signals.

5.18 Analog program signal It should comply with the provisions of GB/T 6278.

5.19 Voice Transmission Index Instrument The voice transmission index meter should meet the following requirements.

a) Test signal. pseudorandom pink noise (its envelope conforms to the typical speech spectrum of IEC 60268-16).

b) Octave filters. 125Hz, 250Hz, 500Hz, 1kHz, 2kHz, 4kHz and 8kHz.

c) Modulation frequency. - STI method. 0.63Hz, 0.8Hz, 1.0Hz, 1.25Hz, 1.6Hz, 2.0Hz, 2.5Hz, 3.15Hz, 4.0Hz, 5.0Hz, 6.3Hz, 8.0Hz, 10Hz, and 12.5Hz; - RASTI method. 500Hz. 1.02Hz, 2.03Hz, 4.07Hz, 8.14Hz; 2000Hz. 0.73Hz, 1.45Hz, 2.90Hz, 5.81Hz, 11.63Hz; - STIPA method. Same as STI method (excluding 1.6Hz and 8.0Hz).

d) Input sensitivity. 94dB is generated by a 30mV input.

6.1.1 Transmission Frequency Characteristics

6.1.1.1 General Provisions Transmission frequency response measurement includes measurements of both acoustic input transmission frequency response and electrical input transmission frequency response. Measurements were taken at various locations within the auditorium seating area. The method for calculating the average steady-state sound pressure level at a point or in each frequency band should comply with Appendix A.

6.1.1.2 Acoustic Input Transmission Frequency Characteristics 6.1.1.2.1 Measurement Principle Block Diagram Measurements can be taken using either the substitution method (see Figure 1) or the comparison method (see Figure 2). Figure

1.Block diagram of the principle of measuring transmission frequency characteristics using the substitution method in the sound input method. Figure

2.Block diagram of the principle of measuring transmission frequency characteristics using the comparison method in the sound input method. 6.1.1.2.2 Measurement Conditions The measurement conditions are as follows:

a) Before measurement, calibrate the sound pressure level measuring instrument using a sound calibrator or piston generator. After measurement, calibrate the instrument using a sound calibrator or piston generator. Re-inspect the sound pressure level measuring instrument. The deviation between the initial and subsequent readings of the sound pressure level measuring instrument should not exceed

0.5 dB.

b) During measurement, the system microphone is placed at the point of use as designed.

c) When the intended point of use is not clearly defined in the design, the system microphone can be placed at the midpoint of the stage curtain line.

d) The center of the system microphone diaphragm is 1.2m to 1.6m above the ground.

e) The directivity of the system microphone is adjusted according to the design requirements.

f) In the comparison method, the system microphone should not be affected by the test microphone.

g) Test the distance between the sound source and the system microphone. 0.5m for speech amplification and 5m for music amplification.

h) Measurements are performed within the transmission frequency range, and the center frequency of the test signal is taken at the center frequency of 1/3 octave band. 6.1.1.2.3 Measurement Procedure The testing steps are as follows:

a) Measurements can be performed using either a band-by-band measurement method or an automatic measurement method.

6.1.2 Transmission Gain

6.1.2.1 Measurement Principle Block Diagram The measurement principle block diagram is shown in Figure 1.

6.1.2.2 Measurement Conditions The measurement conditions are as follows:

a) Set the sound reinforcement system to its highest available gain.

b) Adjust the output of the test system so that the signal-to-noise ratio of the measurement points meets the requirement of 4.3.

6.1.2.3 Measurement Procedure The measurement steps are as follows:

a) Measurements can be performed simultaneously with 6.1.1.2.

b) Place the test sound source at the designated usage point on the stage (or podium). If the designated usage point is unclear, the test sound... The source is placed at the midpoint of the curtain line, 0.5m deep within the stage.

c) Place the sound reinforcement system microphone and the measuring microphone symmetrically on either side of the sound source center on the large curtain line. The distance between the devices is 10cm to 20cm. The height from the ground is 1.2m to 1.6m, and it is the same as the high-frequency sound center of the test sound source.

d) Within the specified transmission frequency range of the sound reinforcement system, sound the sound at each point in the auditorium at a center frequency of 1/3 octave band (or 1/1 octave band). The sound pressure level was measured at each measuring point and at the microphone of the sound reinforcement system.

e) Calculate the average steady-state sound pressure level LFaver according to the calculation method in Appendix A.

6.1.2.4 Expression of Measurement Results The measurement results are presented below.

a) The differenc...