Alarm Types and Testing Alarm Types Normal A

Alarm Types and Testing

Alarm Types Normal A ● B ● C ● D ● High Low ● ● Other Pause OEM / Fleet option Type As required • Fixed Outputs:

SPLs • Fixed Outputs Tonal: Type Normal High Low S = As Standard 68 – 78 85 -95 50 – 58 + [5] d. BA � +[10] d. BA B + X d. BA C S A B C

SPLs • Outputs Types Tonal: Type Normal High Low Per Standard 68 – 78 85 -95 50 – 58 Manual Switched by time or driver or …. Self-Adjusting Stepped Self-Adjusting Continuous

Self-Adjusting • Speaker acting as mic registering overall d. BA • Mic able to filter ambient by: • Frequency range • Impact sounds less than [300] m/s ignored • ? ?

120 Alarm Types 100 Need to define where alarm steps. Graph shows steps at lower and upper limits currently in draft. 80 Difference compared to self-adjusting: Lower step = 10 d. BA Higher step = 8 d. BA 60 40 Ambient Self Adjust Stepped Min Stepped Max 20

Testing • Laboratory / Component Supplier: Type Per Standard Manual Normal High Low 73 +/- 5 d. BA or 72 to 74 +/- 4 d. BA or 71 to 75 +/- 3 d. BA or 70 to 76 +/- 2 d. BA 90 +/- 5 d. BA ditto 54 +/- 4 d. BA Ditto 73 +/- 5 d. BA 90 +/- 5 d. BA 54 +/- 4 d. BA Self-Adjusting Stepped As above [+ 5 d. B(A) ± 4] in addition to the ambient sound in the range of [63 to 100] d. B(A) Self-Adjusting Continuous As above [+ 5 d. B(A) ± 4] in addition to the ambient sound in the range of [63 to 100] d. B(A) Current SAE J 994 allows max of +/- 4 d. BA variation from alarm rated value

Where is ambient measured? Assumed at alarm: 1. Alarm installed at the rear most point of vehicle • Measuring ambient at rear 2. Alarm installed within the vehicle: • Ambient could be quieter; external sounds masked • Ambient could be louder: • from resonance by truck/vehicle body or • other sounds from vehicle

Audibility – ISO 7731 Where is most frequency content in ambient sound? An alarm can often have a lower overall d. BA value than ambient and easily be detectable

OEM / Distributor / Fleet On Vehicle Testing • Fixed Outputs Tonal: Alarm selected based on installation position to ensure sufficient sound is projected to the area of risk. Type Normal High Low S = As Standard 68 – 78 85 -95 50 – 58 + 5 d. BA � +10 d. BA B + X d. BA C Illustrative examples / values S A B C

Tonal v Broadband Sound Fields

Loudness v Audibility Alarm A at 1. 5 k. Hz will seem twice as loud at Alarm C!