Products - SL 4080, Data Logging Sound Level Meter

• SPL & Leq with timer
• RS 232 PC interface
• Min & Max. level calculation
• Date & Time display
• Wide range : 35 to 135 dB
• Informative, bright LCD display
• Light weight & portable
• 9V Battery operation, provided for ext. dc

SL 4080 is a hand held, integrating, data logging sound level meter with PC interface. It measures parameters SPL (Sound Pressure Level) & Leq (equivalent Sound Level). Fig 1 is overall schematic of SL 4080, Fig 2 explains displayed information.

Leq is a time weighted average of time varying SPL. It is value of a steady-state sound which has the same sound energy as that contained in the time-varying sound for any desired duration. Leq correlates reasonably well with the effects of noise on people.

Leq = (1/ΔT) ∑ SPLi x Δti

Where, ΔT is total duration of measurement, SPLi is i th sample of SPL, Δti is the duration for which level remained at SPLi.

In datalogging ( also called recording) mode, instrument measures SPL or Leq, displays readings every 500 ms or 1s, saves readings in its non volatile memory at user selected sampling rate (setting of sampling rate is explained below). Each reading is date and time stamped. Other information saved with each reading is parameter being measured ( SPL or Leq), measuring range, filter & time response selected, serial no. of reading.