Sound level meter - Frequently Asked Questions

By installing the optional 1/1 real-time octave analysis (LA-0563), frequency analysis using a 1/1 octave filter becomes possible, as shown below.

• Measurement of instantaneous values
• Measurement of equivalent noise/single-event noise exposure levels
• Measurement of NC (Noise Criteria) values

 

1. List of Important Notes

• The optional 1/1 real-time octave analysis (LA-0563) must be purchased separately.
• The 1/1 real-time octave filter has a gain of 10dB.
• You cannot select the 1/1 real-time octave filter while the calculation is in progress.
• Please note that the 1/1 real-time octave filter cannot be selected when dual calculation mode is selected.
• If Wide Range is selected, you cannot select the 1/1 Real-Time Octave Filter. Please set an appropriate range other than Wide before selecting the 1/1 Real-Time Octave Filter.
• The AC/DC signal output terminal of the sound level meter outputs an ALLPASS1 signal.
• ALLPASS refers to the signal level without the octave filter applied.
• ALLPASS1 is the main unit in dual mode, and ALLPASS2 is the sub-unit. However, the dynamic characteristics cannot be set independently.
• Frequency analysis is performed on ALLPASS1.

 

2. Measurement of instantaneous values

To measure instantaneous values using a 1/1 real-time octave filter, follow these steps. For basic measurement condition settings, please refer to the "Setting Measurement Conditions" section.

 

◆Operation

• Set the measurement conditions for instantaneous values.

  Frequency Correction Characteristics	: Optional (Panel switch [A/C/FLAT])
  Dynamic characteristics	: Optional (Panel switch [F/S/IMP])
  Measurement mode	Instantaneous value: INST (Panel switch [Tact Max])
  Level range	: Except wide range (Panel switch [LEVEL ▲ ▼])

• 1/1リアルタイムオクターブフィルターを選択する。
  パネルスイッチ［THRU/FILTER］を押すと1/1リアルタイムオクターブフィルターが選択され、画面は1/1リアルタイムオクターブ通常画面（棒グラフ画面）に切り替わります。なお、他のオプションが組み込まれている場合には、パネルスイッチ［THRU/FILTER］を押した後、パネルスイッチ［1/11/3 R.T］を押してください。
• Switch the frequency correction characteristics of ALLPASS2.
• 最初に、切り替わった1/1リアルタイムオクターブ通常画面（棒グラフ画面）のALLPASS2にカーソルを移動します。なお、カーソルはパネルスイッチ［FILTERFREQ］を押して移動させます。次に、パネルスイッチ［A/C/FLAT］を押し、ALLPASS2の周波数補正特性を切り替えてください。
• Read the instantaneous value displayed.
• You can read the bar graph data by moving the cursor. Note that the bar graph screen showing instantaneous measured data can be switched to a list view screen by pressing the [LIST] panel switch.

 

4. Measurement of equivalent noise/single-event noise exposure levels

Measure the equivalent noise/single-event noise exposure level using a 1/1 real-time octave filter using the following procedure:

<Memo>

• Band peaks and time-weighted noise levels cannot be measured.
• Peak values are only found for ALLPASS1 and ALLPASS2.
• The AC signal output terminal outputs the ALLPASS1 signal.
• Please note that the 1/1 real-time octave filter cannot be selected when Dual Calculation Mode or Wide Range is selected.

 

◆Operation

• Set the measurement conditions for instantaneous values.

  Frequency Correction Characteristics	Optional (Panel switch [A/C/FLAT])
  Dynamic characteristics	Optional (Panel switch [F/S/IMP])
  Measurement mode	Instantaneous value (Panel switch [Tact Max])
  Level range	Other than wide range (Panel switch [LEVEL ▲ ▼])
  Measurement time	Within 100 hours (Panel switch [MEAS TIME])

• Select the 1/1 real-time octave filter.
  Pressing the [THRU/FILTER] panel switch selects the 1/1 real-time octave filter, and the screen switches to the normal 1/1 real-time octave screen (bar graph screen).
  If other options are installed, press the panel switch [THRU/FILTER], then press the panel switch [1/11/3 RT].
• ALLPASS2の周波数補正特性を切り替える。
  最初に、切り替わった1/1リアルタイムオクターブ通常画面（棒グラフ画面）のALLPASS2にカーソルを移動します。なお、カーソルはパネルスイッチ［FILTERFREQ］を押して移動させます。
  次に、パネルスイッチ［A/C/FLAT］を押し、ALLPASS2の周波数補正特性を切り替えてください。
• 測定を開始する。
  測定時間をパネルスイッチ［MEAS TIME］で設定した後、パネルスイッチ［START］を押して測定を開始します。
  測定中は測定実行中マークが、測定時間の設定表示には測定の経過時間がそれぞれ表示されます。
• Read the measured value from the digital display.
  The measurement will end once the set measurement time has elapsed.
  The measured data can be switched by pressing the panel switch [LP/Leq…].
  Additionally, by pressing the panel switch [FILTER FREQ] and moving the cursor, you can read the band data of the bar graph selected by the cursor.
  The bar graph screen can be switched to the list view screen by pressing the [LIST] panel switch.

 

5. Measurement of NC (Noise Criteria) values

The NC value is an evaluation quantification proposed in 1957 by L.L. Beranek in the United States. This evaluation quantification was compiled based on a large-scale survey of office noise and a questionnaire survey of employees working in offices, targeting steady-state noise with a broadband spectrum, such as air conditioning noise. For the target noise, the sound pressure level for each octave band of the noise is compared with the NC curve shown below, and if all bands fall below a reference curve, the numerical value of that curve is taken as the evaluation quantification (NC value).

 

■NC curve

 

■Measurement method

◆Operation

• Set the measurement conditions for instantaneous values.

  Frequency Correction Characteristics	: FLAT (Panel switch [A/C/FLAT])
  Dynamic characteristics	: Optional (Panel switch [F/S/IMP])
  Measurement mode	: Instantaneous value (Panel switch [Tact Max])
  Level range	: Except wide range (Panel switch [LEVEL ▲ ▼])
  Measurement time	: Within 100 hours (Panel switch [MEAS TIME])

• Select the 1/1 real-time octave filter.
  Pressing the panel switch [THRU/FILTER] selects the 1/1 real-time octave filter, and the screen switches to the normal 1/1 real-time octave screen (bar graph screen). Note that if other options are installed, after pressing the panel switch [THRU/FILTER], press the panel switch [1/11/3
• Start measurement.
  After setting the measurement time using the [MEAS TIME] panel switch, press the [START] panel switch to begin the measurement. During measurement, a measurement progress indicator will be displayed, and the elapsed measurement time will be displayed on the measurement time setting display.
• Read the displayed measurement value.
  The measurement will end once the set measurement time has elapsed. The NC value will be displayed when the measurement is complete. The following is an example screen showing the measurement of an NC value of 70.

 

6. Memory Operations

This section describes the procedure for storing measurement data in memory using a 1/1 real-time octave filter, and the procedure for recalling the stored data. For details on the memory function, please refer to Chapter 4, "Memory Function and Operation," in this manual. Note: If the calculation data is not real-time data, data cannot be stored. Please be aware of this.

 

■ Procedure for storing measurement data

Data measured with a 1/1 real-time octave filter can be stored in memory using the following procedure.

 

◆Operation

• メモリーモード（FSCAN）を起動する。
  パネルスイッチ［Mem Mode］を押すとメモリーモードが起動します。
• Set the memory address where the data will be stored.
  Each time you press the panel switch [Address▲・▼], the address number will increase or decrease. Note that a mark (#) will appear after address numbers that already have data stored.
• 測定を開始する。
  測定の詳細については、本節「7.3 瞬時値の測定」～「7.5 NC値の測定」をご覧ください。
• Select the data to store.
  Press the panel switch [Lp/Leq] to select the type of data to store.
• Store the measured data.
  Pressing the [Store] panel switch will store the data measured in operation ③ into the memory address set in operations ① and ②. Once the storage is complete, the address number will automatically increment by one level.

 

■Continuous storage procedure for measurement data

◆Operation

• メモリーモード（FSCAN）を起動する。
  パネルスイッチ［Mem Mode］を押すとメモリーモードが起動します。
• Set the memory address where the data will be stored.
  Each time you press the panel switch [Address▲・▼], the address number will increase or decrease. Note that a mark (#) will appear after address numbers that already have data stored.
• 測定を開始する。
  測定時間をパネルスイッチ[MEAS TIME]で設定した後、パネルスイッチ[2nd]、[START]を押して連続測定を開始します。
• ストアするデータを選択する。
  パネルスイッチ[2nd]、［Lp/Leq］を押しストアするデータの種類を選択します。
• Store the measured data.
• パネルスイッチ[2nd]、［Store］を押すと、操作③で測定したデータが、操作①と②で設定したメモリーのアドレスへストアされます。ストアが終了すると、アドレス番号が自動的に1段繰り上がり再び測定を開始し、測定が終了するとメモリーにストアされます。ストアを終了させるまでこれを繰り返します。
• We are closing the store.
  Pressing the panel switch [2nd] or [Store] will end the store operation, but the measurement will continue until the measurement time is up. (During this time, the memory cannot be recalled.) If you want to recall the data immediately, press the panel switch [PAUSE].

 

■Store Data Recall Procedure

Measurement data stored in memory can be recalled using the following procedure.

<Memo>

• If you switch the address number while the data is recalled, the recall data will also be switched.

 

◆Operation

• メモリーモード（FSCAN）を起動する。
  パネルスイッチ［Mem Mode］を押すとメモリーモードが起動します。
• Set the address of the memory to be recalled.
  Press the panel switch [Address▲・▼] to switch to the address number where the data to be recalled is stored. Note that a mark (#) will be displayed after the address number where the data is stored.
• We will carry out a recall.
  Pressing the [Recall] panel switch will read (recall) the data stored in memory. The recalled measurement data can be switched to a list display by pressing the [LIST] panel switch. To turn off (cancel) the recall, press the [Recall] panel switch again. The following is an example screen showing the recall of data for address number 2.

<Memo>

• Addresses where real-time data is stored will be marked with a # symbol.
• Addresses where filter scan data is stored will be marked with an asterisk (*).