Rion NL-42 Specification sheet

3-20-41 Higashimotomachi, Kokubunji, Tokyo 185-8533, Japan
http://www.rion.co.jp/english/
TECHNICAL NOTES
Sound Level Meter
NL-42 / NL-52

i
Organization of the NL-42/NL-52 documentation
Documentation for the Sound Level Meter NL-42/NL-52 comes in three
parts, as listed below.
Instruction Manual
Describes operating procedures for the Sound Level Meter NL-42/NL-52,
connection and use of peripheral equipment such as a level recorder and
printer, and use of the memory card.
Serial Interface Manual
Describes communication with a computer, using the serial interface built
into the Sound Level Meter NL-42/NL-52. The manual covers the com-
munication protocol, use of control commands for the sound level meter,
format of data output by the sound level meter, and other topics.
Technical Notes (this document)
This document provides in-depth information about sound level meter
performance, microphone construction and characteristics, inuence of
extension cables and windscreen on the measurement, and other topics.
* Company names and product names mentioned in this manual are usually
trademarks or registered trademarks of their respective owners.

ii
Contents
Organization of the NL-42/NL-52 documentation .......................... i
Microphone.....................................................................................1
Construction and operation principle .........................................1
Thermal characteristics..............................................................2
Humidity characteristics ............................................................3
Specications of microphone UC-59..........................................4
Specications of microphone UC-52..........................................5
Preamplier ....................................................................................6
Preamplier Requirement ..........................................................6
Preamplier Specications .......................................................6
Inuence of Microphone Extension Cable.......................................7
Frequency Weighting Network ........................................................8
RMS Detection Circuit and Time Weighting...................................9
Measurement Functions ................................................................12
LAeq (equivalent continuous sound level) .................................12
LAE (Sound exposure level) .....................................................13
LN(percentile sound level) ......................................................14
Lmax, Lmin (maximum and minimum sound level) ...................14
LAtm5 (takt-max sound level)....................................................15
Lpeak (peak sound level) ..........................................................15
Inuence of Background Noise .....................................................16
Description for IEC 61672-1.......................................................... 17
IEC 61672-1 (JIS C 1509-1) frequency response ......................27
Reference incidence direction and reference point position......28
Frequency response ................................................................29
Inuence of body reection ....................................................30
Acoustical inuence of operator ..............................................31
Reduction of wind noise by windscreen ..................................32
Effect of All-Weather Windscreen WS-15 ...............................34
Effect of Rain-protection Windscreen WS-16 .........................35

iii
The greatest susceptibility conguration for
radio frequency elds...............................................................36
Statement of conforming to the basic statement ......................36
Adjustment data for sound calibrator .......................................37
The lower and upper limits of the linear operating range.........38
Directional Characteristics ......................................................39
Random incidence response.....................................................43

iv

1
Microphone
Measurements of sound pressure level can be carried out with a variety of
microphone types. The sound level meter NL-52 employs the prepolarized
condenser microphone UC-59 (NL-42 employs UC-52) that is compact and
delivers stable and reliable response.
Construction and operation principle
As shown in the illustration below, an electret condenser microphone normally
consists of ve main parts, namely the diaphragm, lm, backplate, insulator,
and case. A lm with an electrical charge is normally mounted to the back-
plate. When sound pressure is applied to the diaphragm, the distance between
the diaphragm and the backplate changes, thereby altering the capacitance.
Using a load resistor, this change can be turned into a voltage change. The
frequency response as well as the temperature and humidity characteristics
of an prepolarized condenser microphone depend considerably on the type
and properties of the materials used. The high frequency range is determined
by the resonance frequency of the diaphragm assembly.
Sound pressure
Diaphragm
Film
Case
Load resistance
Output
Backplate
Insulator
Insulator
Construction of prepolarized condenser microphone

2
Microphone
Thermal characteristics
The thermal characteristics of a microphone indicate how sensitivity changes
at various temperatures. The diagrams below show the thermal characteristics
of the microphone UC-59 and UC-52.
Temperature (°C)
Thermal characteristics of UC-59 (at 250 Hz)
Response (dB)
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
-30 -20 -10 0 10 20 30 40 50 60 70
Response (dB)
Temperature (°C)
Thermal characteristics of UC-52 (at 250 Hz)
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
-30 -20 -10 0 10 20 30 40 50 60 70

3
Microphone
Humidity characteristics
The humidity characteristics of a microphone indicate how sensitivity changes
at various humidity levels. The diagrams below show the microphone UC-59
and UC-52.
Relative humidity (%)
Humidity characteristics of UC-59 (at 250 Hz)
Response (dB)
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
020406080100
Response (dB)
Relative humidity (%)
Humidity characteristics of UC-52 (at 250 Hz)
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
0 20 40 60 80 100

4
Microphone
Specications of microphone UC-59
Model: UC-59
Nominal diameter: 1/2 inch
Sensitivity: -27 dB ±2 dB (re. 1 V/Pa)*
Frequency response: 10 to 20000 Hz
Capacitance: 13 pF ±1.5 pF
Temperature dependent sensitivity level uctuation:
±0.35 dB max. from -10 to +50ºC
referenced to 23ºC (at 1 kHz)
±0.5 dB max. from -20 to +60ºC
referenced to 23ºC (at 1 kHz)
Humidity dependent sensitivity level uctuation:
±0.14 dB max. referenced to 23ºC, 50%RH
90%RH max.
(at 1 kHz no condensation)
Ambient temperature/humidity range for operation:
-20 to +60ºC, 90%RH max.
(no condensation)
Ambient temperature range for storage:
-20 to +60ºC
Dimensions, weight: 13.2 dia × approx. 14.3 mm, approx. 4.7 g
*Reference environment conditions:
Temperature: 23ºC, Humidity: 50%RH
Atmospheric pressure: 101.325 kPa