DR-7100 Frequently Asked Questions

Instructions for use ■ Recording sound data for analysis

1. Device Setup

-1. Regarding the input condition settings for the DR-7100

The V_RNG (voltage range) is initially set to 1 V, so considering the AC output of the sound level meter, please set it to the "3.16 V" or "10 V" range (10 V for safety, 3.16 V for accuracy). When recording sound data with Ono Sokki 's 1/2-inch microphone with constant current preamplifier, set the voltage range as a guideline: 0.1 V if the expected sound pressure level is 94 dB or less, 1 V if it is 114 dB or less, and 10 V if it is higher.

Please leave both the HPF (high-pass filter) and LPF (low-pass filter) at their default settings (OFF). Leave the SAMP_RNG (sampling frequency) at its default setting (20 kHz, AC), and the SAMP_MOD can be set to either "FFT" or "AUDIO". For INPUT (input format), set it to AC if the recording sensor is a sound level meter, or to CCLD if it is a microphone with a constant current preamplifier.

-2. Setting up the sound level meter

We recommend recording the sound data output from the sound level meter to the DR-7100 without applying frequency weighting.

When using models such as LA-1410, LA-1440, LA-4440, LA-2560, LA-3560, and LA-3570, it is possible to set the sound pressure display of the sound level meter to have frequency weighting enabled, while the signal from the AC output terminal is not frequency weighted. However, to monitor for range overload of the sound level meter, it is recommended to set the display to not have frequency weighting.
Before recording with the DR-7100, measure the sound you plan to record using a sound level meter and check that the sound level meter does not show a range over error within the set level range. If a range over error occurs, readjust the level range to an appropriate one. If the sound you plan to record is not reproducible and you cannot adjust the level range, we recommend using the wide range setting.

2. Recording of calibration signal data

-1. When recording sound with a sound level meter

Before recording sound data, calibration signal data will be recorded. Please refer to "Equipment Settings" above for the settings of the sound level meter and DR-7100. Connect the AC-OUT terminal of the sound level meter to the DR-7100.

● When using the internal calibration signal of the sound level meter
Press the "CAL" button on the sound level meter to output calibration signal, which will then be recorded on the DR-7100. A data length of approximately 10 seconds is sufficient. When recording actual sound data and when recording the "calibration signal," ensure the sound level meter is set to the same level range. If recording at multiple level ranges, record the "calibration signal" each time the level range is changed. When recording the "calibration signal," be sure to record the displayed value on the sound level meter. Also, record which sound data was measured at the same level range.

● When using an acoustic calibration
Use an acoustic calibration to input a calibration signal from the microphone and record the output signal of the sound level meter on the DR-7100. When recording actual sound data and when recording the "calibration signal," set the sound level meter to the same level range. If recording at multiple level ranges, record the "calibration signal" each time the level range is changed. When recording the "calibration signal," be sure to record the sound pressure value indicated on the acoustic calibration. Also, record which sound data was measured at the same level range.

● When recording sound using a microphone with a constant current preamplifier
Before recording audio data, record a "calibration signal." Refer to the "Equipment Settings" section above for microphone and DR-7100 settings. Use an acoustic calibration to input calibration signal from the microphone and record the output signal on the DR-7100. When recording the "calibration signal," be sure to record the sound pressure value indicated on the acoustic calibration.

3. Recording of audio data

Record audio data to the DR-7100 using a sound level meter or a microphone with a constant-current preamplifier. When recording data with a sound level meter, pay attention to the level range. If you record audio data at a certain level range using a sound level meter, be sure to record a calibration signal at the same level range.

■ Calculation of calibration values using Ausscope Basic

calibration signal data recorded in the DR-7100 is imported into Ausscope Basic, and the voltage value per 1 Pa of sound pressure is calculated.

● Determine the voltage value of calibration signal.
The RMS value is calculated on calibration signal data, and the magnitude is read at the point where the RMS value stabilizes. The reading "x dB" at this time indicates that "when 1 Vrms is used as the reference (0 dB), the current signal magnitude is "x dBVrms"." From this, when the RMS value is "x dB," the voltage value expressed without decibels is 10 ^(x/20) Vrms.

*When performing RMS calculations on calibration signal data, please set the frequency weighting to "Z characteristic (FLAT)".

● Determine the Pa value of calibration signal
We determine what Pa corresponds to calibration value displayed on the sound level meter or the value displayed on the sound pressure calibration. The value displayed on the sound level meter indicates the "sound pressure level when the sound pressure is 20 × ^10⁻⁶ Pa as the reference." If calibration value displayed on the sound level meter or the value displayed on the sound pressure calibration is "a dB," then the sound pressure at that time is 10⁻⁶ Pa ⁽where b is the sound pressure level at 1 Pa = 20 log(1/(20 × ^10⁻⁶)) = 93.9794).

● Calculate V/EU (how many volts are equivalent to 1 Pa).
Divide the voltage value obtained above by the Pa value. V / Pa = 10 ^{((x-a+93.9794)/20)}

Calculation example

When calibration using the internal signal of the sound level meter, if the displayed value of the sound level meter is 104.0 dB and the effective value of calibration signal on the audioscope is -9.031 dBVrms, then:

The sound pressure is 3.1698, the RMS voltage is 0.35355, and calibration value (V/Pa) is 0.1115 V/Pa.

■ Changing file information using Ausscope Basic

By setting calibration values for the sound data included in Auscope Basic, it becomes possible to read sound pressure and sound pressure level.

● Changing calibration value
Open "Channel Settings" in "Data Editing". Change the "Signal Type" of the audio data to "Sound Pressure Level" (because the reference value when calculating the sound pressure level is 20 × ^10⁻⁶ Pa). Write calibration value you calculated earlier into "1/EU" in "Channel Settings" (0.1115 if following the previous example).

After changing this setting, sound data can be read in Pa units. Furthermore, by performing RMS calculations, it becomes possible to read the data as sound pressure level (dB).

* Open the "Channel Settings" for calibration signal data, set the "Signal Type" to "Sound Pressure Level," and write the calculated calibration value to "1/EU." After changing these settings, perform an RMS calculation on the sound data. If the sound pressure level (dB) is the same as the recorded calibration value, you can confirm that the calculation was correct.