Rion NL-42, NL-52 Technical Notes

TECHNICAL NOTES

Sound Level Meter

NL-42 / NL-52

3-20-41 Higashimotomachi, Kokubunji, Tokyo 185-8533, Japan

http://www.rion.co.jp/english/

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.

i

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

(equivalent continuous sound level) .................................12

L

Aeq

LAE (Sound exposure level) .....................................................13

LN (percentile sound level) ...................................................... 14

L

, L

(maximum and minimum sound level) ...................14

min

(takt-max sound level) ....................................................15

(peak sound level) ..........................................................15

L

L

max

Atm5

peak

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

ii

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

iii

iv

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

Backplate

Insulator

Load resistance

Output

Construction of prepolarized condenser microphone

Insulator

Case

1

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.

0.5

0.4

0.3

0.2

0.1

0

-0.1

Response (dB)

-0.2

-0.3

-0.4

-0.5

-30 -20 -10 0 10 20 30 40 50 60 70

Temperature (°C)

Thermal characteristics of UC-59 (at 250 Hz)

0.5

0.4

0.3

0.2

0.1

0

-0.1

Response (dB)

-0.2

-0.3

-0.4

-0.5

-30 -20 -10 0 10 20 30 40 50 60 70

Temperature (°C)

Thermal characteristics of UC-52 (at 250 Hz)

2

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.

0.5

0.4

0.3

0.2

0.1

0

-0.1

Response (dB)

-0.2

Microphone

-0.3

-0.4

-0.5

020406080100

Relative humidity (%)

Humidity characteristics of UC-59 (at 250 Hz)

0.5

0.4

0.3

0.2

0.1

0

-0.1

Response (dB)

-0.2

-0.3

-0.4

-0.5

0 20 40 60 80 100

Relative humidity (%)

Humidity characteristics of UC-52 (at 250 Hz)

3

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

4

Speci cations of microphone UC-52

Model: UC-52

Nominal diameter: 1/2 inch

Sensitivity: -33 dB (re. 1 V/Pa)*

Frequency response: 20 to 8000 Hz

Capacitance: 19 pF

Diaphragm type: Titan alloy  lm

Temper a tu re co e f  cient: -0.008 dB / ºC (at 250 Hz)

Humidity-dependent sensitivity change:

0.1 dB or less

(at 250 Hz, 95%RH or below, no condensation)

Dimensions, weight: 13.2 dia. × 12 mm, 5.4 g

*Reference environment conditions:

Microphone

Temperature: 23ºC, Humidity: 50%RH

Atmospheric pressure: 101.325 kPa

5

Preampli er

Preampli er Requirement

Since the condenser microphone is a small-capacity transducer, it has high

impedance, especially at low frequencies. Therefore a very high load resis-

tance is required to ensure uniform response extending to the low frequency

range. The relationship between the microphone capacitance and the low-

range cutoff frequency can be expressed as follows.

f

0: Low-range cutoff frequency (Hz)

Zin: Preampli er input impedance (Ω)

Cm: Capacitance of condenser microphone (F)

If the output of the microphone were directly routed through a long shielded

cable, the capacitance between the cable conductors would cause a sharp

drop in sensitivity, as is evident from the following equation.

M0: Output voltage into directly connected shielded cable (V)

Ms: Output voltage in microphone open condition (V)

Cc: Cable capacitance of shielded cable (F)

For the above reasons, a preampli er of high input impedance is connected

directly after the microphone, to provide a low-impedance output signal.

Preampli er Speci cations

Model name: NH-24 (NL-42) NH-25 (NL-52)

Input impedance: Approx. 3 GΩ // 9 pF Approx. 3 GΩ // 27 pF

Output resistance: Approx. 50 Ω Approx. 50 Ω

6

In uence of Microphone Extension Cable

When the output of the microphone/preampli er is routed through an exten-

sion cable, certain limitations regarding measurable sound pressure level and

frequency range will apply. This is due to the in uence of the cable capaci-

tance. The longer the cable, the lower the measurable sound pressure level

and the lower the frequency limit.
Available cables are listed in the table below. Combining multiple cables is

also possible.

Model

EC-04

EC-04A

EC-04B

Length

2m

5m

10 m

Extension cable EC-04 series

Model

EC-04C

EC-04D

EC-04E

30m(
50m(reel)+5 m (connection cable)

100m(reel)+5 m (connection cable)

Length

reel)+5 m (connection cable)

The diagram below shows the relationship among cable length, measurable

sound pressure level, and frequency.

If for example a sound pressure level of 132 dB is to be measured up to 10

kHz, an extension cable length of up to 500 meters can be used.

Cable length

138

400 m

130

500 m

120

110

Measurable sound pressure level (dB SPL)

100

100 200 500 1 k 2 k 5 k 10 k 20k

Frequency (Hz)

7

Frequency Weighting Network

The NL-42/NL-52 provides frequency weightings A, C and Z. The electri-

cal characteristics of the weighting network at AC output connector are as

shown below.

10

Z weighting

0

-10

C weighting

A weighting

10 20 50 100 200 500 1 k 2 k 5 k 10 k 20 k 50 k

Frequency (Hz)

Response (dB)

-20

-30

-40

-50

-60

-70

C weighting

Z weighting

A weighting

Frequency weighting

The volume impression (loudness) of a sound depends not only on the sound

pressure level, but also on the frequency. At high or low frequencies, a sound

is felt to be less loud than a sound of equal level in the midrange. The fre-

quency weighting A compensates for this effect and produces measurement

results which are close to the actual impression of loudness. For this reason,

this type of frequency weighting is widely used for purposes such as sound

level evaluation.

With the frequency weighting Z, frequency response is linear, which is suit-

able for sound pressure level measurements and for using the sound level

meter output for frequency analysis.

The frequency weighting C curve produces almost  at response, but with a

roll off below 31.5 Hz and above 8 kHz. This is suitable for sound pressure

level measurements in situations with unwanted low-frequency or high-fre-

quency components.

8

RMS Detection Circuit and Time Weighting

The sound level meter uses rms detection. The rms value E (rms) is de ned

by the following equation.

T

1

E(rms) =

The voltage e which changes over time is raised to the second power, and

integration for the time interval T is performed. The result is divided by T

and the square root is extracted. The circuit con guration for performing the

above mathematical operation looks as follows.

The NL-42/NL-52 uses digital processing to determine the rms value.

e2dt

T

0

ei

Input Voltage

Second power

2

ei

T

1

T

0

2

ei

E(rms)

2

ei

Output Voltage

9

RMS Detection Circuit and Time Weighting

During sound level measurements, the level often  uctuates drastically,

which would make it dif cult to evaluate readings if some kind of averaging

is not applied. Sound level meters therefore provide the capability for index

weighting (index averaging) using the rms circuit. The parameters of this

weighting process are called the time weightings, determined by the time

constant (see next page).

Sound level meters usually have a F (Fast) and S (Slow) setting for the time

weighting. The time range that is considered for averaging is narrow in the

F (Fast) setting and wide in the S (Slow) setting. In the F (Fast) setting, the

instantaneous level has a larger bearing on the displayed value than in the S

(Slow) setting. From the point of view of the measurement objective, the F

(Fast) setting is more suitable to situations wit h swiftly cha nging sound level,

whereas the S (Slow) setting yields a more broadly averaged picture.

The F (Fast) setting is more commonly used, and sound pressure level values

given without other indication are usually made with F (Fast) characteris-

tics.

The S (Slow) setting is suitable for measuring the average of sound with

fairly constant levels. For example, in Japan aircraft noise and high-speed

train noise is usually transient noise with high  uctuation, but the S (Slow)

setting is used to determine the maximum level for each noise event.

The I (Impulse) setting enables the meter to track noise bursts of very

short duration. (When optional Extended Function Program NX-42EX is

installed.)

10

Time weightings and time constant

RMS Detection Circuit and Time Weighting

1s

35 msec

Time constant

Decay time

125 msec

1s

1.5 sec

Time

Weighting

F (Fast)

S (Slow)

I (Impulse)

Rise time

125 msec

The time weighting network of the sound level meter performs index averaging

on the square of the sound pressure signal. The equivalent circuit is shown

below. is the time constant, which equals CR.

R

e

i

Equivalent electrical circuit

C

=CR

ei: Input voltage (proportional to square

e

o

of sound pressure)

eo: Output voltage

The response of the index averaging circuit to a single burst signal is shown

below.

e1: Burst signal voltage
e : Logarithm base

: Time constant

t : Time

t

11

e1

1-

rms amplitude

Signal amplitude

e1

1

e

Burst signal response

Measurement Functions

L

L

L

(equivalent continuous sound level)

Aeq

For a sound pressure level signal that changes over time, the L

continuous sound level) is a hypothetical constant sound pressure level that

has the same energy as the actually measured signal in the measurement

interval. It is determined by the following equation.

t2

AeqT

t: Time variable of integration from an arbitrary start time at t

the end of the interval at t2

T: Time interval T = t2 - t1

pA(t): A-weighted instantaneous sound pressure at running time t

p0: Reference sound pressure (20 μPa)

In sound pressure level meter NL-42/NL-52, the digital processing to deter-

mine L

is carried out according to the following equation.

Aeq

20 log

10

1

T

2

p

(t )

A

t1

dt

½

p

Aeq

0

(equivalent

1 to

12

N

2

p

A

Aeq

N: Number of samples

In NL-42/NL-52, the sampling interval is 20.8 μs (48000 samples per sec-

ond).

20 log

10

N

1

i=1

(i )

½

p

0

LAE (Sound exposure level)

The LAE (sound exposure level) is a hypothetical constant 1-second sound

pressure level having the same energy as a single-event sound pressure level

measured with A weighting. It is determined by the following equation.

2

t

2

L

10 log

AE

10

t: Time variable of integration from an arbitrary start time at t1 to

the end of the interval at t2

T: Time interval T = t2 - t1

T0: Reference time (1 second)

pA(t): A-weighted instantaneous sound pressure at running time t

p0: Reference sound pressure (20 μPa)

p

(t )

dt

A

t1

Measurement Functions

2

p

T

0

L

0

Aeq

10 log

(TT0)

10

In NL-42/NL-52, the digital processing to determined L

is carried out

AE

according to the following equation.

2

N

p

L

0: Number of samples per second

N

AE

10 log

10

N0

1

i=1

(i )

A

2

p

0

In NL-42/NL-52, the sampling interval is 20.8 μs (48000 samples per sec-

ond).

13

Measurement Functions

LN (percentile sound level)

The LN (percentile sound level) is the sound level which was N percent or

more of the measurement time. The NL-42/NL-52 allows the user to select

L

 ve values for N (from 1 to 99, in 1 steps). The sampling interval for L

processing is 100 ms (10 samples per second) or L

max

, L

L

(maximum and minimum sound level)

min

is the maximum sound level and L

max

the minimum sound level encoun-

min

eq, 1s

.

tered during a measurement.

In NL-42 / NL-52, t he sampling i nterva l is 20.8 μs (4800 0 samples per second).

The maximum and minimum values since the start of the measurement are

stored. Therefore the L

max

and L

readings up to the current point can be

min

displayed already during measurement.

N

14

Measurement Functions

N

L

Atm5

(takt-max sound level)

For the duration of the measurement, the maximum level within a 5-second

interval is sampled and the power average is determined. L

according to the following equation.

N

L

Atm

: Maximum level within interval (5 seconds)

L

m

N: Number of samples

The number of samples is determine according to the following equation.

For L

t1: Measurement start time

Atm5

:

10 log

t

(

2

5

1

10

N

i=1

t

)

1

Lm/10

10

is calculated

Atm

L

t2: Measurement end time

(peak sound level)

peak

The peak sound level is a maximum absolute value of frequency weighted

instantaneous sound pressure level during the measuring time.

15

In uence of Background Noise

When measuring a certain sound in a certain location, all other sounds present

at that location except the measurement target sound are background noise

(also called ambient noise or dark noise). Since the sound level meter will

display the combination of target sound and background noise, the amount

of background noise must be taken into consideration when determining the

level of the target sound.

If the difference between the meter reading in absence of the target sound

and the reading with the target sound is 10 dB or more, the in uence of back-

ground noise is small and may be disregarded. If the difference is less than

10 dB, the values shown in the table below may be used for compensation,

to estimate the level of the target sound.

Background noise compensation

Display reading difference with

and without target sound (dB)

Compensation value (dB)

If for example the measured sound level when operating a machine is 70 dB,

and the background noise level when the machine is not operating is 63 dB,

the compensation value for the difference of 7 dB is -1 dB. Therefore the

sound level of the machine can be taken to be 70 dB + (-1 dB) = 69 dB.

The above principle for compensating the in uence of the background noise

assumes that both the background noise and the target sound are approxi-

mately constant. If the background noise  uctuates, and especially if it is

close in level to the target sound, compensation is dif cult and will often be

meaningless.

456 789

-2 -1

16

Description for IEC 61672-1

Standard

paragraph

4 Reference environmental

5Performance speci cations

5.1 General

5.1.4 Con guration & normal

5.1.6 Models of microphone

5.1.7 Mounting of microphone 9.2.1 b)

5.1.8 Identi cation of computer

5.1.10 Description of frequency

5.1.12 Description of level ranges

5.1.13 Reference SPL

5.1.14 Operating of the hold fa-

5.1.15 Dummy microphone: De-

Description

conditions

mode of operation

Appropriate procedures for
use the sound level meter

software

weightings that are pro­vided

(@ A-weig hted SPL @
1 kHz )
Instruction manual of the
level range controls and
function.
Recommendation for se­lecting the optimum level
range.

reference level range,
reference orientation, ref­erence position of micro­phone.

cility and the means for
clearing a display that is
held.

sign goal and tolerance

See

also

9.1 Ambient temperat ure:

9.2 .1 b) Con  guration

9.2 .1 c)

9.2 .5 b)

9.2.2 c) A, C, Z A, C, Z

9.2 .2 h)

9.2 .5 c)

9.2 .5 a),

9.3 a),
b), c)

9.3 g) Capacitance of dummy

Remark

NL-52 NL-42

Ambient temperature:
23°C
Static pressure:

101.325 kPa
Relative humidity:50%

• NL-52

• WS-10

Controls and Functions,
Preparations

UC-59

Measurement

Controls and Functions,
Preparations

N/A N/A

25 dB to 138 dB

N/A

N/A

94 dB
N/A
Reference incidence
direction and reference
point position (Fig. 1)

Measurement Measurement

microphone: 13 pF
Tole r a n c e : ±1.5 pF

23°C

Static pressure:

101.325 kPa

Relative humidity:50%

Con guration

• NL- 42

• WS-10
Controls and Functions,
Preparations

UC-52

Measurement

Controls and Functions,
Preparations

25 dB to 138 dB

N/A

N/A

94 dB
N/A
Reference incidence
direction and reference
point position (Fig. 1)

Capacitance of dummy
microphone: 19 pF
Tole r a n c e : ±3 pF

17

Description for IEC 61672-1

Standard

paragraph

5.1.16 Highest SPL and Peak-

5.1.17 Characteristics of each in-

5.1.18 Initial time interval after

5.2 Adjustment to indicated levels

5.2.1 Model of

5.2.3 Procedure for calibration

5.2.4

5.2.5

5.2.7 Adjustment data for sound

5.4 Frequency weightings

5.4.12 Frequency response & tol-

5.5 Level linearity

5.5.9 A, C and Z weighted levels

Description

Peak input voltage without
causing damage.

dependent channel to be
described

switching on power

sound calibrator(s)

& adjustment with sound
calibrator
Data for correction - with
and without windscreen

- for :

- Deviation of average fre­quency response to uni­form frequency response.

- Case re ection and mi­crophone diffraction
Including values for ex­panded uncertainties.
In 1/3 octave frequencies
for 63 Hz to 1 kHz and
1/12 octave frequencies
for 1 kHz to 16 kHz

calibrator or electrostatic
actuator (for A-weighted
sound levels)

erances of optional fre­quency responses

for the lower and upper
limit of the linear operat­ing range.

See

also

9.3 i) 148 dB

9.2.5 e) Less than 90 seconds Less than 90 seconds

9.2.4 a) NC-74 (RION) NC-74 (RION)

9.2 .4 c)

9.2 .4 d)

9.2 .5 b)

9.3 d) Adjustment data for sound

9.2 .2 c) N/A N/A

9.3 e) The lower and upper lim-

Remark

NL-52 NL-42

150 dB

11 Vp-p

N/A N/A

Calibration Calibration

Frequency response of
the microphone UC-59
(Fig. 2)
Frequency response of
the NL-52/NL-42 (in­cluding the case re ec­tion) (Fig. 4)
In uence of WS-10 on
acoustic performance of
NL-52/NL-42 (Fig. 10)
Frequency response with
windscreen correction
(WS-10) (Fig. 11)
Refer to IEC 61672-1 (JIS
C 1509-1) frequency re­sponse (Tab. 1)

calibrator (Tab. 3)

its of the linear operating
range (Tab. 4)

11 Vp-p

Frequency response of
the microphone UC-52
(Fig. 3)
Frequency response of
the NL-52/NL-42 (in­cluding the case re ec­tion) (Fig. 4)
In uence of WS-10 on
acoustic performance of
NL-52/NL-42 (Fig. 10)
Frequency response with
windscreen correction
(WS-10) (Fig. 11)
Refer to IEC 61672-1 (JIS
C 1509-1) frequency re­sponse (Tab. 1)
Adjustment data for sound
calibrator (Tab. 3)

The lower and upper lim­its of the linear operating
range (Tab. 4)

5.5.10 Starting point for the level
linearity error

18

9.3 f) The lower and upper lim­its of the linear operating
range (Tab. 4)

The lower and upper lim­its of the linear operating
range (Tab. 4)

Description for IEC 61672-1

Standard

paragraph

5.5.11 How to test level linearity

5.6 Self generated noise

5.6.1 Self-noise at the more

5.6.3 Self-noise at the more sen-

5.6.5 Instruction to measure low

5.7 Time weighting F and S

5.7.1 Description of time weight-

5.10 - 5.11

5.10.1 Operation & interpretation

5.11.1 Operation & interpretation

5.12 Peak C sound level

5.12.1 Nominal range of L

5.14 Thresholds

5.14 Operation of user-select-

5.15 Display

5.15.2 Description of the indica-

5.15.3 Description of the dis-

Description

if display range < linear­ity range

sensitive ranges (includ­ing microphone)

sitive ranges with dummy
microphone

level sounds with consid­eration of influence of
self-noise

ings that are provided

Overload and Under-range indication

of overload indicators

of under-range indicators

at

Cpeak

for each level range

able thresholds

tion of displayed quanti­ties

play

See

also

9.3 k) N/A N/A

9.2 .5 o)

9.3 h)

9.3 h) Dummy microphone (13

9.2 .5 d)

9.2.2 d) F(Fast), S(Slow) F(Fast), S(Slow)

9.2 .5 k)

9.2 .2 i) N/A

9.2 .5 l) N/A N/A

9.2 .2 g)

9.2 .2 g)

Maximum value
A: <17 dB
C: <25 dB
Z: <30 dB
Typica l va l u e
A: 13 dB
C: 20 dB
Z: 25 dB

pF)
Maximum value
Equal to 5.6.1
Typica l va l u e
A: 11 dB
C: 16 dB
Z: 21 dB

The lower and upper lim­its of the linear operating
range (Tab. 4)

NL-52 NL-42

In uence of back-

ground noise

Controls and Func­tions

Controls and Func­tions

Controls and Func­tions

Controls and Func­tions

Remark

Maximum value
A: <19 dB
C: <27 dB
Z: <32 dB
Typica l va l u e
A: 15 dB
C: 22 dB
Z: 27 dB
Dummy microphone (18
pF)
Maximum value
Equal to 5.6.1
Typica l va l u e
A: 13 dB
C: 18 dB
Z: 24 dB

In uence of back-

ground noise

Controls and Func­tions

Controls and Func­tions

N/A
The lower and upper lim­its of the linear operating
range (Tab. 4)

Controls and Func­tions

Controls and Func­tions

19

Description for IEC 61672-1

Standard

paragraph

5.15.4 Description of the dis-

5.15.5 Statement of the display

5.15.6 Time inter val for comple-

5.15.7 Description of method for

5.16 Analogue and digital outputs

5.16.1 Electric output connector

5.17 Timing facilities

5.17.1 Procedure to preset the

5.17.2 Statement of the minimum

5.18 RF emissions and power supply disturbance

5.18.1 Length & type of interface

Description

played quantities

update rate

tion of the integration

transferring data to PC

(AC output)

Electric output connector
(DC output)

integration time & time
of the day

& maximum integration
time

cable and characteristics of
connected devices

See

also

9.2 .2 a) N/A N/A

9.2.2 g) 1 second 1 second

9.2.5 f) Less than 1 second Less than 1 second

9.2 .5 m) N/A
Refer to serial interface
manual

9.2 .5 p) Frequency weighti ng: A,
C, Z
Output voltage:
1 Vrms (at output level
range upper)
Output range:
4 Vrms or less
Output impedance: 600
Ω
Load impedance: >10
kΩ
Frequency weighting: A,
C, Z
Output voltage:

2.5 V (at output level
range upper), 25 mV/dB
Output range:
0 to 5 V
Output impedance: 50
Ω
Load impedance: >10
kΩ

9.2 .5 g)

9.2.5 h) Minimum: 1 second
Maximum: 24 hours

9.2 .5 n)

Microphone extension
cable EC-04 series (up
to 35 m)
Output cable CC-24 (2.5
m)
All cables shielded

NL-52 NL-42

Preparations

Remark

N/A
Refer to serial interface
manual

Frequency weighting: A,
C, Z
Output voltage:
1 Vrms (at output level
range upper)
Output range:
4 Vrms or less
Output impedance: 600
Ω
Load impedance: >10
kΩ
Frequency weighting: A,
C, Z
Output voltage:

2.5 V (at output level
range upper), 25 mV/dB
Output range:
0 to 5 V
Output impedance: 50
Ω
Load impedance: >10
kΩ

Preparations

Minimum: 1 second
Maximum: 24 hours

Microphone extension
cable EC-04 series (up
to 35 m)
Output cable CC-24 (2.5
m)
All cables shielded

20

Description for IEC 61672-1

Standard

paragraph

5.18.2 Operating mode or h igh-

5.20 Power supply

5.20.2 Maximum and minimum

5.20.3 Battery types & battery

5.20.4 Operation from an external

5.20.5 Public power supply volt-

6 Environmental, electrostatic and radio frequency criteria

6.1.2 Time interval for needed

6.2.2
(Note)

6.5.2 Degradation of functions

6.6.1 Operating mode with least

Description

est radio frequency emis­sions

power supply voltage

life

power supply

age

to stabilize after environ­mental changes

Measurement when static
pressure is < 85 kPa

by electrostatic discharge

immunity to AC power
frequency  elds and RF
 elds

See

also

9.3 n) Operation mode: normal
operation
Connection pattern:
AC adapter NC-98
Output cable CC-24
Communication cable
CC-42R
USB cable (with ferrite
cores)
Microphone extension
cable EC-04 series 35 m

9.3 j Maximum: 7 V
Minimum: 4 V

9.2 .3 a) N/A
LR6 × 4: approx. 15
hours

9.2 .3 c)

9.2.3 d) 100 to 240 V AC (toler­anc e range 9 0 to 264 V),
50/60 Hz (47 to 63 Hz)

9.3 l) Temperature change: <
1 hour
Humidity change:
< 1 hour
Static pressure change:
< 5 minutes
Calibration and measure­ment performed in this
environment using Sound
Calibrator NC-74

9.2.7 b) Measurement value af­fected temporarily by
electrostatic discharge

9.3 o) Fig. 16
Operation mode: normal
operation
Connection pattern:
AC adapter NC-98
Output cable CC-24
Communication cable
CC-42R
USB cable (with ferrite
cores)
Microphone extension
cable EC-04 series 35 m

NL-52 NL-42

Preparations

Remark

Operation mode: normal
operation
Connection pattern:
AC adapter NC-98
Output cable CC-24
Communication cable
CC-42R
USB cable (with ferrite
cores)
Microphone extension
cable EC-04 series 35 m

Maximum: 7 V
Minimum: 4 V
N/A
LR6 × 4: approx. 15
hours

Preparations

100 to 240 V AC (toler­anc e range 9 0 to 264 V),
50/60 Hz (47 to 63 Hz)

Temperature change: <
1 hour
Humidity change:
< 1 hour
Static pressure change:
< 5 minutes
Calibration and measure­ment performed in this
environment using Sound
Calibrator NC-74
Measurement value af­fected temporarily by
electrostatic discharge
Fig. 16
Operation mode: normal
operation
Connection pattern:
AC adapter NC-98
Output cable CC-24
Communication cable
CC-42R
USB cable (with ferrite
cores)
Microphone extension
cable EC-04 series 35 m

21

Description for IEC 61672-1

Standard

paragraph

6.6.4
(Note)

Description

Field strength for conform­ing (in case > 10 V/m)

See

also

9.3 m) N/A N/A

NL-52 NL-42

Remark

7 Provisions for use with auxiliary devices

7.1 Correction for use of mi-

9.2 .6 b) N/A N/A

crophone cable

7.2 Ef fe c t of option a l a c c e s ­sories (windscreen)

7.3 St atem ent of con for ma nce
with optional accessories
(wi ndscreen)

7.4 Operation of 1/1 - 1/3 oc-

9.2 .6 a) In uence of WS-10 on
acoustic performance of
NL-52/NL-42 (Fig. 10)
Compliant with IEC
61672-1 (JIS C 1509-1),
with Windscreen WS-10
mounted

In uence of WS-10 on
acoustic performance of
NL-52/NL-42 (Fig. 10)
Compliant with IEC
61672-1 (JIS C 1509-1),
with Windscreen WS-10
mounted

9.2 .6 c) N/A N/A

tave band  lters

7.5 Details about connection

9.2.6 d)

Preparations Preparations

& effects of auxiliary de­vices

9 Instruction manual

9.2 .1 General

9.2.1 a) Description of type, clas-

Group X, Class 1 Group X, Class 2

si cation (X, Y, Z) and
class

9.2.1 b) Overall con guration,
Normal operation con g-

5.1.4

5.1.7

Refer to 5.1.4
Refer to 5.1.7

Refer to 5.1.4

Refer to 5.1.7
uration (including wind­screen)

9.2.1 c) Models of microphones 5.1.6 Refer to 5.1.6 Refer to 5.1.6

9.2.1 d) Re q u i r e d m icro p hone

N/A N/A

cable to conform

9.2 .1 e) Cha r acteristics & o pera-

N/A N/A

tion each channel

9.2.2 Design features

9.2.2 a) Description of quantities
which can be measured

9.2 .2 b) Relative f ree- eld response
as function of incidence an­gle and frequency (detailed
tabular description)

9.2.2 c) Description of the fre­quency weightings

9.2.2 d) Description of the time

5.15.4 Lp, Leq, L

LN, L

peak

Directional Characteris­tics with Horizontal Di­rection (Fig. 17, Tab. 5),
Vertic a l D i rectio n ( Fig.
18, Tab. 6)

5.1.10

5.4.12

Refer to 5.1.10
Refer to 5.4.12

, L

max

, L

Atm5

min

, LE,

Lp, Leq, L
LN, L

peak

max

, L

Directional Characteris­tics with Horizontal Di­rection (Fig. 17, Tab. 5),
Vertic a l D i rectio n (Fig.
18, Tab. 6)
Refer to 5.1.10
Refer to 5.4.12

5.7.1 Refer to 5.7.1 Refer to 5.7.1

weightings

9.2 .2 e) Identi cation of the level

5.1.12 Refer to 5.1.12 Refer to 5.1.12
ranges (A-weighted @ 1
kHz)

9.2.2 f) Operation of the level

5.1.12 Refer to 5.1.12 Refer to 5.1.12
range control

, L

Atm5

min

, LE,

22

Description for IEC 61672-1

Standard

paragraph

9.2.2 g) Description of the display

9.2.2 h) Total range of A- weighted

9.2 .2 i) Nominal range of L

9.2 .2 j) Computer softwa re to op -

9.2 .2 k) Desig n g oa l s a nd tole r-

9.2 .3 Power supply

9.2.3 a) Battery types & battery

9.2.3 b) Description of the function

9.2 .3 c) Operation from an external

9.2.3 d) Public power supply volt-

9.2.4 Adjustment to indicated levels

9.2.4 a) M o d e l of s o u n d

9.2.4 b) Calibration check fre-

9.2.4 c) Procedure for calibration

9.2.4 d) Data for correction - with

9.2.5 Operating the sound level meter

9.2.5 a) Reference direction 5.1.13 Refer to 5.1.13 Refer to 5.1.13

Description

and update rates

SPL (@ 1 kHz)

Cpeak

for each level range

erate the SLM

ances for quantities which
are not in the standard (T­weight 10 ms, L

life

of battery check

power supply

age

calibrator(s)

quency

& adjustment with sound
calibrator

and without windscreen

- for :

- Deviation of average fre­quency response to uni­form frequency response.

- Case re ection and mi­crophone diffraction
Including values for ex­panded uncertainties.
In 1/3 octave frequencies
for 63 Hz to 1 kHz and
1/12 octave frequencies
for 1 kHz to 16 kHz

AIeq

)

See

also

5.15.2­3-4-5

5.1.12 Refer to 5.1.12 Refer to 5.1.12

at

5.12.1 Refer to 5.12.1 Refer to 5.12.1

5.1.8 Refer to 5.1.8 Refer to 5.1.8

5.20.3 Refer to 5.20.3 Refer to 5.20.3

5.20.4 Refer to 5.20.4 Refer to 5.20.4

5.20.5 Refer to 5.20.5 Refer to 5.20.5

5.2.1 Refer to 5.2.1 Refer to 5.2.1

5.2.3 Refer to 5.2.3 Refer to 5.2.3

5.2.4 -

5.2.5

Refer to 5.15.2-3-4-5 Refer to 5.15.2-3-4-5

The lower and upper lim­its of the linear operating
range (Tab. 4)

1 kHz 1 kHz

Refer to 5.2.4 -

5.2.5

NL-52 NL-42

Controls and Func­tions

Remark

The lower and upper lim­its of the linear operating
range (Tab. 4)

Controls and Func­tions

Refer to 5.2.4 -

5.2.5

23

Description for IEC 61672-1

Standard

paragraph

9.2.5 b) Procedure to measure

9.2 .5 c) Recom mendat ion for se-

9.2.5 e) Initial time interval after

9.2.5 f) Time interval for comple-

9.2.5 g) Procedure to preset the

9.2.5 h) Statement of the minimum

9.2.5 i) Operation of the “Hold”

9.2.5 j) Operation of the reset

9.2.5.k) Operation & interpretation

9.2.5 l) Operation of user-select-

9.2.5 m) Description of method for

9.2.5 n) Length & type of interface

9.2.5 o) Self-noise at the more sen-

9.2.5 p) Characteristics of AC and

9.2.6 Accessories

9.2.6 a) Effect of windscreen (di-

Description

sound,
In uence of the instrument
case and operator.

lecting optimum level
range

switching on power

tion of the integration

integration time & time
of the day

& maximum integration
time

function

function or Leq, LE, L
and overload

of overload indicators

able thresholds

transferring data to PC

cable and characteristics of
connected devices

sitive ranges (including
microphone). Averaging
time ≥ 30 s.

DC output

rectional response and
frequency weighting)

peak

See

also

5.1.6

5.2.4

5.2.5

5.1.12 Refer to 5.1.12 Refer to 5.1.12

5.1.18 Refer to 5.1.18 Refer to 5.1.18

5.15.6 Refer to 5.15.6 Refer to 5.15.6

5.17.1 Refer to 5.17.1 Refer to 5.17.1

5.17.2 Refer to 5.17.2 Refer to 5.17.2

5.10.1 Refer to 5.10.1 Refer to 5.10.1

5.14 Refer to 5.14 Refer to 5.14

5.15.7 Refer to 5.15.7 Refer to 5.15.7

5.18.1 Refer to 5.18.1 Refer to 5.18.1

5.6.1 Refer to 5.6.1 Refer to 5.6.1

5.16.1 Refer to 5.16.1 Refer to 5.16.1

7.2 Re fer to 7.2 Refer to 7.2

Refer to 5.1.6
Refer to 5.2.4
Refer to 5.2.5

Measurement results
(measurement values,
overload indication, un­der-range indication) are
reset when a new mea­surement is started.
Time required for mea­surement initialization:
< 1 second

NL-52 NL-42

Measurement Measurement

Remark

Refer to 5.1.6
Refer to 5.2.4
Refer to 5.2.5

Measurement results
(measurement values,
overload indication, un­der-range indication) are
reset when a new mea­surement is started.
Time required for mea­surement initialization:
< 1 second

24

Description for IEC 61672-1

Standard

paragraph

9.2 .6 b)

9.2.6 c) Use of bandpass  lters 7.4 Refer to 7.4 Refer to 7.4

9.2 .6 d)

9.2 .7 In uence of environmental conditions

9.2.7 a) Components intended for

9.2.7 b) Degradation of functions

9.2.7 c) Statement for conformance

9.3 Information for testing

9.3 a) Reference sound pressure

9.3 b) Reference level range 5.1.13 Refer to 5.1.13 Refer to 5.1.13

9.3 c) Microphone reference

9.3 d) For A-weighted sound lev-

9.3 e) N o m in a l A - w e i g h t ed

9.3 f) Starting point for the level

9.3 g) Dummy microphone: De-

9.3 h) Self-noise at the more sen-

9.3 i) Highest SPL and Peak-

Description

Corrections for microphone
cable

Connection of auxiliary
devices

operation in controlled
environment

by electrostatic discharge

to AC power frequency
 elds and RF  elds

level

point

els: Adjustment data for
multi-frequency sound
calibrator and/or electro­static actuator

sound levels at the upper
and lower limits of the
linear operating range on
each level range.

- For frequencies 31.5 Hz,
1, 4, 8 and 12.5 kHz

linearity error

- For frequencies 31.5 Hz,
1, 4, 8 and 12.5 kHz

- At the reference level
range

sign goal and tolerance

sitive ranges with micro­phone and with dummy
microphone

Peak input voltage to ac­commodate

See

also

7.1 Refe r t o 7.1 Refe r t o 7.1

7.5 Re fer to 7.5 R efer t o 7. 5

None None

6.5.2 Refer to 6.5.2 Refer to 6.5.2

Statement of conform­ing to the basic statement
(Tab. 2)

5.1.13 Refer to 5.1.13 Refer to 5.1.13

5.1.13 Refer to 5.1.13 Refer to 5.1.13

5.2.7 Refer to 5.2.7 Refer to 5.2.7

5.5.9 Refer to 5.5.9 Refer to 5.5.9

5.5.10 Refer to 5.5.10 Refer to 5.5.10

5.1.15 Refer to 5.1.15 Refer to 5.1.15

5.6.1 /

5.6.3

5.1.16 Refer to 5.1.16 Refer to 5.1.16

Refer to 5.6.1 /

5.6.3

NL-52 NL-42

Remark

Statement of conform­ing to the basic statement
(Tab. 2)

Refer to 5.6.1 /

5.6.3

25

Description for IEC 61672-1

Standard

paragraph

9.3 j) Maximum and minimum

9.3 k) How to test level linearity

9.3 l)

9.3 m) Field strength for conform-

9.3 n) Operating mode or high-

9.3 o) Operating mode with least

Description

power supply voltage

if display range < linear­ity range
Time interval for needed to
stabilize after environmental
changes

ing (in case > 10 V/m)

est radio frequency emis­sions

immunity to AC power
frequency  elds and RF
 elds

See

also

5.20.2 Refer to 5.20.2 Refer to 5.20.2

5.5.11 Refer to 5.5.11 Refer to 5.5.11

6.1.2 Refer to 6.1.2 Refer to 6.1.2

6.6.4 Refer to 6.6.4 Refer to 6.6.4

5.18.2 Refer to 5.18.2 Refer to 5.18.2

6.6.1 Refer to 6.6.1 Refer to 6.6.1

NL-52 NL-42

Remark

26

Description for IEC 61672-1

IEC 61672-1 (JIS C 1509-1) frequency response

Tab. 1 IEC 61672-1 (JIS C 1509-1) frequency response

Nominal
Frequency
(Hz)

Exact
Frequency
(Hz)

63 63.10 0.1 0.0 -0.1 0.0 0.0 0.0 0.3

80 79.43 0.1 0.0 -0.1 0.0 0.0 0.0 0.3
100 100.0 0.1 0.0 -0.1 0.0 0.0 0.0 0.3
125 125.9 0.1 0.0 0.0 0.0 0.0 0.0 0.3
160 158.5 0.1 0.0 -0.1 0.0 0.0 0.0 0.3
200 199.5 0.1 0.0 0.0 0.0 0.0 0.0 0.2
250 251.2 0.1 0.0 0.0 0.0 0.0 0.0 0.2
315 316.2 0.0 0.0 0.0 0.0 0.1 0.0 0.2
400 398.1 0.0 0.0 0.0 0.0 0.1 0.0 0.2
500 501.2 0.0 0.0 0.1 0.0 0.1 0.0 0.2
630 631.0 0.0 0.0 0.1 0.0 0.1 0.0 0.2
800 794.3 -0.1 0.0 0.1 0.0 0.1 -0.1 0.2

1000 1000 0.0 0.0 0.0 0.0 0.1 -0.1 0.2
1250 1259 0.0 0.0 -0.2 0.0 0.2 -0.1 0.3
1600 1585 0.0 0.1 -0.4 0.0 0.2 -0.2 0.3
2000 1995 0.0 0.2 0.0 0.0 0.3 -0.3 0.3
2500 2512 0.0 0.3 0.2 0.0 0.4 -0.3 0.3
3150 3162 0.1 0.4 0.1 0.0 0.5 -0.4 0.3
4000 3981 0.1 0.4 -0.1 0.0 0.3 -0.4 0.4
5000 5012 0.1 0.3 0.4 0.0 0.0 -0.4 0.4
6300 6310 0.1 0.0 -0.1 0.0 -0.2 -0.3 0.4

8000 7943 0.0 -0.5 0.0 0.0 0.0 -0.1 0.4
10000 10000 -0.1 0.2 0.0 -0.2 0.1 0.6
12500 12589 -0.3 -0.1 0.0 -0.5 0.3 0.6
16000 15849 -0.8 -0.2 0.0 -0.7 0.4 0.6

UC-59
Frequency
Response
(dB)

UC-52
Frequency
Response
(dB)

NL-42/52
Frequency
Response
(dB)

NL-42/52
Electrical
Response
(dB)

Windscreen
(WS-10)
Effect
(dB)

Windscreen
(WS-10)
Correction
(dB)

Total
Expanded
Uncertainty
(dB)

27

Description for IEC 61672-1

Reference incidence direction and reference point position

Reference direction
of incidence

Reference point position
Center of diaphragm plane

Fig. 1 Reference incidence direction and reference point position

28

Frequency response

The frequency response of a sound  eld microphone is expressed as the fre-

quency response in the reference direction of incidence (0º).

The diagram below shows an example for the frequency response of the

microphone UC-59 and UC-52.

4

2

0

-2

-4

Response (dB)

-6

Description for IEC 61672-1

-8

-10

1 10 100 1 k 10 k 100 k

Frequency (Hz)

Fig. 2 Frequency response of the microphone UC-59

4

2

0

-2

-4

Response (dB)

-6

-8

-10

10 100 1k 10 k 100 k

Frequency (Hz)

Fig. 3 Frequency response of the microphone UC-52

29

Description for IEC 61672-1

In uence of body re ection

The NL-52/NL-42 is designed to minimize re ections caused by the body

of the unit.

The chart below shows the in uence on the measurement.

6

4

2

0

Response (dB)

-2

-4

-6
100

1000

Frequency (Hz)

10000

Fig. 4 In uence of Body re ection

100000

30

Acoustical in uence of operator

6

4

2

0

Response (dB)

-2

-4

-6
10 20 50 100 200 500 1 k 2 k 5k 10 k 20k

Frequency (Hz)

Fig. 5 Acoustical in uence of operator (the distance from the top

of the microphone to the operator is approx. 40 cm)

6

Description for IEC 61672-1

4

2

0

Response (dB)

-2

-4

-6
10 20 50 100 200 500 1 k 2 k 5k 10 k 20k

Frequency (Hz)

Fig. 6 Acoustical in uence of operator (the distance from the top

of the microphone to the operator is approx. 70 cm)

Sound arrival direction

Sound level meter

160 cm

120 cm

Approx. 40cm or 70 cm

Fig. 7 Measurement conditions for acoustical in uence of operator

31

Description for IEC 61672-1

Reduction of wind noise by windscreen

During outdoor measurements or measurement of ventilation devices, wind

noise can falsify measurement results. To counter such problems, the supplied

windscreen WS-10 should be mounted on the microphone. The characteristics

of the WS-10 are shown below. The attenuation of wind noise produced by

the windscreen is about 25 dB with frequency weighting A and 15 dB with

frequency weighting C.

The in uence of the windscreen WS-10 on the acoustic performance of the

microphone is within ±1.0 dB up to 12.5 kHz, as shown in the diagram on

the next page.

100

Microphone only

90

80

70

60

50

40

Wind noise level (dB A)

30

2 5 10 20

With WS-10

130

120

Microphone only

110

100

90

80

70

60

Wind noise level (dB C)

2 5 10 20

With WS-10

wind velocity (m/s) wind velocity (m/s)

Fig. 8-1 Frequency weighting A Fig. 8-2 Frequency weighting C

100

wind velocity

15 m/s

10 m/s

5 m/s

1/3 octave band sound

pressure level (dB)

90

80

70

60

50

40

20 50 100 200 500

Frequency (Hz)

32

Fig. 9 Frequency response of wind noise measured with

windscreen WS-10 mounted microphone

Description for IEC 61672-1

1.0

0.0

-1.0

Response (dB)

10 50 100 500 1 k 5 k 10 k 50 k

Frequency (Hz)

Fig. 10 In uence of windscreen WS-10 on acoustical properties

of microphone (refer red to microphone response without
windscreen)

3.0

2.0

1.0

0.0

-1.0

Response (dB)

-2.0

-3.0

-4.0

-5.0
10 50 100 500 1 k 5 k 10 k 50 k

Windscreen attached, with no correction for it
Windscreen attached, with correction for it

Frequency

(Hz)

Fig. 11 Frequency response with windscreen correction (WS-10)

33

Description for IEC 61672-1

Effect of All-Weather Windscreen WS-15

The windscreen WS-15 not only reduces measurement errors due to wind

noise, it also protects the microphone from rain.

The WS-15 characteristics are shown below.

130

Microphone only

120

With WS-15

110

100

90

80

70

60

50

Wind noise level (dB)

40

30

1 10 100

Wind velocity (m/s)

Fig. 12-1 Frequency weighting A Fig. 12-2 Frequency weighting C

130

Microphone only

120

With WS-15

110

100

90

80

70

60

50

Wind noise level (dB)

40

30

110100

Wind velocity (m/s)

3

2

1

0

-1

Response (dB)

-2

-3

-4

-5

100 1000 10000 100000

Windscreen attached, with no correction for it
Windscreen attached, with correction for it

Frequency (Hz)

Fig. 13 Frequency response with windscreen correction (WS-15)

34

Description for IEC 61672-1

Effect of Rain-protection Windscreen WS-16

The windscreen WS-16 not only reduces measurement errors due to wind

noise, it also protects the microphone from rain.

The WS-16 characteristics are shown below.

100

Microphone only

90

80

70

60

50

40

Wind noise level (dB A)

30

2 5 10 20

With WS-16

130

120

Microphone only

110

100

90

80

70

60

Wind noise level (dB C)

2 5 10 20

With WS-16

wind velocity (m/s) wind velocity (m/s)

Fig. 14-1 Frequency weighting A Fig. 14-2 Frequency weighting C

3

2

1

0

-1

Response (dB)

-2

-3

-4

-5

100 1000 10000 100000

Windscreen attached, with no correction for it
Windscreen attached, with correction for it

Frequency (Hz)

Fig. 15 Frequency response with windscreen correction (WS-16)

35

Description for IEC 61672-1

The greatest susceptibility configuration for radio
frequency  elds

LCD

Antenna

Polarized electromagnetic
radiation is parallel to this space

AC OUTPUT, DC OUTPUT,
Comparator and USB cable connected

Fig. 16 The greatest susceptibility con guration for radio frequency  elds

Statement of conforming to the basic statement

Tab. 2 Statement of conforming to the basic statement

NL-52 NL-42

Immunity (AC power fre­quency magnetic  eld)

Immunity (Radio fre­quency electromagnetic
 eld)

The speci cation of IEC
61672-1 Class 1 is satis­ ed

The speci cation of IEC
61672-1 Class 1 is satis­ ed

The speci cation of IEC
61672-1 Class 2 is satis­ ed

The speci cation of IEC
61672-1 Class 2 is satis­ ed

Emissions

36

The speci cation of IEC
61672-1 Class 1 is satis­ ed

The speci cation of IEC
61672-1 Class 2 is satis­ ed

Adjustment data for sound calibrator

Tab. 3 Adjustment data for sound calibrator

Description for IEC 61672-1

Frequency (Hz)

NL-52

Correction (dB)

31.5 0.0 0.0

63 0.0 0.0

125 0.0 0.0

250 0.0 0.0

500 0.0 0.0

1000 0.0 0.1

2000 0.2 0.3

4000 0.9 1.3

8000 3.0 3.2

12500 5.9 6.5

16000 7.3 6.7

NL-42

Correction (dB)

37

Description for IEC 61672-1

The lower and upper limits of the linear operating range

Tab. 4 The lower and upper limits of the linear operating range

A weighting

31.5 Hz 1 kHz 4 kHz 8 kHz 12.5 kHz

Upper

Start

Lower

C weighting

Upper

Start

Lower

Z weighting

Upper

Start

Lower

98.0 138.0 138.0 136.0 133.0

94.0 94.0 94.0 94.0 94.0

25.0 25.0 25.0 25.0 25.0

31.5 Hz 1 kHz 4 kHz 8 kHz 12.5 kHz

135.0 138.0 137.0 135.0 131.0

94.0 94.0 94.0 94.0 94.0

33.0 33.0 33.0 33.0 33.0

31.5 Hz 1 kHz 4 kHz 8 kHz 12.5 kHz

138.0 138.0 138.0 138.0 138.0

94.0 94.0 94.0 94.0 94.0

38.0 38.0 38.0 38.0 38.0

Measurement range

Upper

Lower

38

(dB)

L

A

(dB)

L

C

(dB)

L

Z

L

Cpeak

(dB)

L

Zpeak

138.0 138.0 138.0 141.0 141.0

25.0 33.0 38.0 55.0 60.0

(dB)

Directional Characteristics

The directional characteristics of a microphone is a measure of its differing

sensitivity for sound waves arriving from various angles. Since the prepolar-

ized condenser microphone used in the NL-52/NL-42 is a pressure-sensitive

type, it should be equally sensitive in all directions. However, refraction

and cavity effects cause a certain microphone directional response at high

frequencies.

The diagrams below shows the directional characteristics for the NL-52/

NL-42.

00°

10°

20°

280°

290°

300°

310°

320°

330°

340°

350°

5dB

0dB

-5dB

-10dB

-15dB

Description for IEC 61672-1

Reference direction
of incidence

30°

40°

50°

60°

70°

80°

130°

120°

90°

100°

110°

1 kHz
2 kHz
4 kHz
8 kHz

12.5 kHz

270°

260°

250°

240°

230°

220°

210°

200°

190°

-20dB

180°

170°

160°

140°

150°

Fig. 17 Directional Characteristics of NL-52/NL-42 (Rotated horizontal)

39

Description for IEC 61672-1

Tab. 5 Directional Characteristics of NL-52/NL-42 (Rotated horizontal)

Angle

°

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

250

260

270

280

290

300

310

320

330

340

350

Frequency (Hz)

1k 2k 4k 8k 12.5k

0.00 0.00 0.00 0.00 0.00

°
°
°
°
°
°
°
°
°

°
°
°
°
°
°
°
°
°
°
°
°
°
°
°
°
°
°
°
°
°
°
°
°
°
°

0.12 -0.02 0.05 -0.07 -0.20

0.09 -0.09 0.01 -0.67 -0.79

0.17 -0.16 -0.13 -0.94 -1.17

0.16 -0.28 -0.66 -1.13 -1.59

0.25 -0.50 -0.72 -1.96 -2.73

0.26 -0.72 -0.54 -2.52 -3.89

0.27 -0.58 -1.07 -2.23 -4.35

0.21 -0.30 -1.19 -3.29 -5.64

0.10 -0.18 -2.09 -3.83 -6.23

-0.23 -0.44 -1.53 -3.87 -6.47

-0.42 -0.51 -1.57 -4.17 -7.93

-0.66 -0.22 -0.69 -5.48 -7.19

-0.76 -0.36 -1.56 -4.61 -9.92

-0.68 -0.87 -1.11 -3.51 -6.97

-0.49 -1.04 -1.91 -4.34 -7.94

-0.29 -0.73 -2.98 -4.72 -8.22

-0.18 -0.45 -1.60 -5.04 -8.48

-0.13 -0.32 -0.87 -3.24 -6.93

-0.11 -0.32 -1.41 -4.66 -9.42

-0.25 -0.61 -2.55 -4.61 -8.24

-0.45 -0.91 -1.83 -4.51 -7.85

-0.67 -0.82 -1.18 -3.07 -6.65

-0.78 -0.30 -1.44 -3.85 -9.49

-0.73 -0.07 -0.61 -4.76 -7.16

-0.49 -0.28 -1.28 -4.16 -7.54

-0.20 -0.36 -1.55 -2.90 -6.68

0.03 -0.04 -1.57 -3.28 -6.24

0.14 -0.14 -0.86 -2.70 -5.22

0.15 -0.48 -0.38 -1.96 -4.06

0.18 -0.65 -0.32 -1.92 -3.59

0.14 -0.43 -0.41 -1.63 -2.10

0.13 -0.20 -0.19 -0.88 -1.56

0.08 -0.07 0.08 -0.63 -1.11

0.07 -0.04 0.13 -0.01 -0.50

0.02 -0.06 -0.10 0.02 -0.03

40

280°

270°

290°

300°

310°

320°

330°

340°

350°

5dB

0dB

-5dB

-10dB

-15dB

-20dB

00°

10°

20°

Description for IEC 61672-1

Reference direction
of incidence

30°

40°

50°

60°

70°

80°

90°

130°

120°

100°

110°

1kHz
2kHz
4kHz
8kHz

12.5 kHz

260°

250°

240°

230°

220°

210°

200°

190°

180°

170°

160°

140°

150°

Fig. 18 Directional Characteristics of NL-52/NL-42 (Rotated vertical)

41

Description for IEC 61672-1

Tab. 6 Directional Characteristics of NL-52/NL-42 (Rotated vertical)

Angle

°

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

250

260

270

280

290

300

310

320

330

340

350

Frequency (Hz)

1k 2k 4k 8k 12.5k

0.00 0.00 0.00 0.00 0.00

°
°
°
°
°
°
°
°
°

°
°
°
°
°
°
°
°
°
°
°
°
°
°
°
°
°
°
°
°
°
°
°
°
°
°

0.06 0.01 0.06 -0.03 -0.20

0.05 -0.04 0.15 -0.46 -0.42

0.08 -0.11 0.06 -0.64 -1.06

0.13 -0.26 -0.61 -1.03 -1.90

0.16 -0.49 -0.43 -2.12 -2.23

0.23 -0.70 -0.39 -2.40 -3.64

0.23 -0.49 -1.11 -2.51 -4.54

0.12 -0.25 -0.76 -3.22 -5.22

0.05 -0.27 -1.91 -3.66 -6.06

-0.07 -0.32 -0.78 -3.77 -6.73

-0.35 -0.51 -1.91 -4.17 -7.28

-0.61 -0.12 -0.85 -4.46 -7.85

-0.76 -0.23 -1.79 -4.31 -8.37

-0.67 -0.89 -0.23 -3.99 -7.78

-0.45 -1.06 -1.68 -4.75 -7.90

-0.19 -0.79 -3.29 -4.38 -6.31

-0.05 -0.37 -1.51 -6.40 -9.85

-0.02 -0.27 -0.81 -3.23 -7.07

-0.10 -0.33 -1.52 -5.28 -10.12

-0.18 -0.66 -3.07 -4.54 -5.65

-0.41 -0.97 -1.78 -3.34 -6.85

-0.56 -0.87 -0.25 -3.53 -8.46

-0.67 -0.30 -1.50 -4.77 -8.89

-0.56 0.15 -0.86 -4.80 -7.81

-0.26 -0.19 -1.83 -4.81 -7.86

0.01 -0.22 -0.81 -3.77 -6.99

0.16 -0.32 -1.40 -3.02 -6.00

0.20 -0.41 -0.58 -3.30 -6.02

0.21 -0.53 -1.01 -2.44 -4.74

0.16 -0.57 -0.24 -1.93 -3.83

0.14 -0.31 -0.25 -1.91 -2.44

0.06 -0.09 -0.39 -1.25 -1.82

0.02 -0.03 -0.02 -0.62 -1.23

0.07 -0.02 0.06 -0.73 -0.64

0.04 0.12 -0.03 -0.02 -0.17

42

Random incidence response

(dB)

6

4

2

0

-2

Response (dB)

-4

-6

-8

-10

1 10 100 1000 10000 100000

Description for IEC 61672-1

Frequency (Hz)

Fig. 19 Random incidence response

43

No. 55753 13-06