Sound Level Meter Model 831 Larson Davis

Sound Level Meter Specifications

Averaging ( Integration method )

Linear or Exponential

RMS Time Weighting

Slow, Fast or Impulse

Frequency Weightings

A, C or Z

Peak Detector Frequency Weighting

A, C or Z

Gain

0 dB or +20 dB

Exchange Rates

3, 4, 5, or 6 dB with optional 831-IH

Sample Rate

51,200 Hz

Peak Rise Time

30 μμs

Physical Characteristics

Length with Microphone and Preamplifier

11.35 in 

29.0 cm

Length, Instrument  Body Only

8.8 in 

22.4 cm

Width

2.8 in 

7.1 cm

Depth 

1.6 in 

4.1 cm

Weight with Batteries, No Preamplifer or Microphone 

13.6 oz

390 g

Weight with Batteries, Preamplifer and Microphone 

1.2 lb 

550 g

General Specifications

Reference level 

114.0 dB re. 20 μPa

Reference level range 

Single  large  range  for SLM Normal  for OBA option,  Gain 0 dB

Reference frequency 

1000 Hz

Reference direction 

0° is perpendicular to the microphone diaphragm

Temperature

≤ ± 0.5 dB error between +14 to +122 °F ( -10 to 50 °C )

Storage temp.

-13 to +158 °F ( -25 to +70 °C )

Humidity 

≤ ± 0.5 dB error from 30% to 90% relative  humidity at 104 °F ( 40 °C )

Equivalent Microphone Impedance 

12 pF for Larson Davis 1/2 in microphone

Range  Level Error (OBA option)

 ≤ ± 0.1 dB relative to the reference range

Digital Display update  Rate

Four times per second  ( 0.25 sec between updates ). First display indication is available 0.25 seconds after initiation of a measurement.

Effect of an Extension Cable 

None ( up to 200 ft or 61 m with  EXCxxx cable )

Electrostatic Discharges 

The instrument is not adversely affected by electrostatic discharges

Extended Weather Options 

-40 to +158 ºF ( -40 to +70 ºC ) operation with CER-831-E

Resolution Specifications

Levels 

0.1 dB

Dose 

0.1%

Elapsed time

0.1 second

Real time clock 

1 second

Calendar Through 

31 Dec 2100

Integration Time

Time Averaged Levels and Sound Exposure Levels ( s )

Minimum

0.1 second

Maximum with Daily Autostore Enabled 

Unlimited

Maximum with Daily Autostore Disabled 

> 23 days with error < 0.5 dB

Dosimeter  Metrics :  TWA, Dose ( s )

Minimum

0.1 second

Maximum

Unlimited

Ln Statistics

Number of selectable parameters

6 in xx.xx% format, visible on the Model 831

Storage of Complete Table

0.1 dB Steps

Spectral Statistics

Requires Octave Analysis option ( 831-OB3 )

Markers

Number of Markers 

10

Prenamed Markers 

5 : Truck, Automobile, Motorcycle, Aircraft, Exclude

link Marker to Automatic Sound Recording

Yes, requires Sound Recording option ( 831-SR )

Back Erase

Back Ease Time

5 or 10 seconds

Supported Modes 

Manual

Measurement Control Modes

Available Modes

Manual Stop, Timed Stop, Stop when Stable, Continuous, Single Block Timer, Daily Block Timer

Timed Stop Time in

hh:mm:ss

Stop When Stable

Delta level in xx.x dB and time in hh:mm:ss

Continuous with Daily Auto-Store

1, 2, 4, 6, 12, 24, 48, 96 or 144 files per day, automated  file numbering “yymmddnn.LD0”

Continuous Restart on Power Failure

Automatic if powered  by 12VDC

Single Block Timer

Start date and time to End data and time

Daily Block Timer

Up to 3 blocks with each start and end date, blocks can cross date line

Clock Stability

< 1 sec in 24 hours, at 75 ºF ( +24 ºC )

< 10 sec in 30 days, at -40 to +158 ºF ( -40 to +70 ºC )

Digital Voice Annotation

Annotate Recordings

Use headset ( ACC003 ) or  measurement microphone

Recording Sample Rate

8 ksps

Listening Options

On the Model 831 or using processing software for .wav files