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Messages - FaberAST

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1
SignalScope / Re: RTA Averaging
« on: November 16, 2017, 10:05:20 PM »
Yes. With those settings, you'll get the average sound level over 20 seconds in each whole or 1/3 octave band, plus an overall (full bandwidth) average level. You can see the overall level by tapping the graph to turn on the cursor.

2
SignalScope / Re: RTA Averaging
« on: November 16, 2017, 08:45:38 AM »
Based on your description, I would recommend that you look in the Octave Analyzer options menu and set Level Type to Leq, turn on Auto Stop, and set the duration to 20 seconds.

3
SignalScope / Re: RTA Averaging
« on: November 07, 2017, 03:39:50 PM »
What would you like to do with averaging?

4
SignalScope / Re: RTA Averaging
« on: November 01, 2017, 02:46:45 PM »
In SignalScope, you'll see an info button (a little 'i' in a circle) on the right side of the toolbar at the top of the screen. Tap that, and then tap on Help.

5
SignalScope / Re: RTA Averaging
« on: October 30, 2017, 06:10:15 PM »
Hi,

The Octave analyzer tool (RTA) supports both exponential (Lp) and linear (Leq) averaging of the signal in each whole or 1/3-octave frequency band. For exponential averaging, Fast, Slow, and Impulse time weightings are supported. For linear averaging, the average level is calculated over the entire duration of the measurement.

SignalScope's built-in documentation includes information on how to access the averaging options.

Let us know if you have more questions.

6
Electroacoustics Toolbox / Re: Basic setup guide
« on: April 27, 2017, 06:46:29 PM »
Steve,

If you are trying to perform dual-channel measurements (e.g. frequency or impulse response), I would point you to the tutorial on the blog for reference.
Frequency Response Measurement with Electroacoustics Toolbox 3

Why can't you use the output of the Duet to use the built-in test signals? Perhaps, a more detailed description of what you are trying to do, and how you would like to set it up, would help us zero in on a suitable solution.

Ben

7
Stuart,

Bluetooth mic input is typically sampled at 8 kHz. The weighting filters in the Meter and the bandpass filters in the Octave analyzer are designed to operate at multiples of 44.1 kHz and 48 kHz, which would explain the "Unsupported Sample Rate" message.

It seems that some time ago Apple changed the behavior of Bluetooth audio in iOS (at least in the Measurement Mode that SoundMeter uses). Since SoundMeter requires both input and output from the audio system, Bluetooth won't work unless you are using a Bluetooth headset (or hearing aids, in your case) with both input and output. Unfortunately, if you use a headset for input and output, then the sample rate will be restricted to 8 kHz (for both input and output).

This is a change from how Bluetooth used to work on iOS, when it was possible to use the built-in mic with Bluetooth output.

I wish I had better news.

Ben

8
Zoe,

I'm not aware of any affordable sound level meter software for Windows.

You might consider an iPod touch as a less expensive alternative to the iPhone. The accuracy of your measurements will depend on the quality of your calibration, regardless of which device you use. You can get more reliable measurements with an external measurement microphone, like the MicW i436.

Ben

9
SoundMeter / Re: Using Exteral Microphones and Calibration
« on: January 25, 2016, 10:27:37 AM »
SoundMeter's built-in documentation includes a device input voltage calibration tutorial.

To access the documentation, tap the info button ("i") in the toolbar at the top of the main screen. Then, tap on Help in the Info screen.

10
Electroacoustics Toolbox / Re: nan dB
« on: October 26, 2015, 08:26:51 PM »
"nan" stands for "not a number" and indicates that some invalid arithmetic operation occurred (like dividing zero by zero).

11
SignalScope Pro / Re: THD measurement
« on: October 16, 2015, 01:43:00 PM »
Quote
Am I correct in assuming that the number of spectral lines is equivalent to the number of bins?
Yes. Each line represents one bin.

12
SignalScope Pro / Re: THD measurement
« on: August 13, 2015, 10:24:41 AM »
SignalScope Pro's FFT Analyzer tool is capable of computing THD with up to 15 harmonics.
In order to get good results, you'll need to use a test signal that's at a frequency that matches one of the frequency bins in the FFT. This is fairly simple if you use SignalScope Pro's built-in signal generator and use the same audio device for both output and input in your measurements.

13
IOScope / Re: Feature suggestions
« on: March 16, 2015, 10:26:13 AM »
IOScope 5 added frequency smoothing in 1/6th, 1/12th, and 1/24th octave band resolution. It also added support for loading previously captured measurements for direct comparison with the live curve.

14
SoundMeter / Re: Dayton Audio iMM-6 External Mic
« on: March 12, 2015, 04:27:41 PM »
Bruce,

I'm sorry, I obviously misread your post.

Are you looking for frequency response compensation (FRC) or sensitivity calibration? If you are looking for FRC, it is not supported in SoundMeter. FRC only works with FFT-based spectrum analysis.

If you are looking for sensitivity calibration, then you would need to enter the iMM-6's acoustic pressure sensitivity in the Input Channels calibration screen (there is calibration tutorial information in SoundMeter's built-in documentation).

The iMM-6's calibration file includes the mic's overall sensitivity on the first line. (You can download the file directly at http://www.daytonaudio.com/iMM6_Lookup_Tool/iMM_Text/99-00192.txt, where you replace "00-00192" with your own mic's serial number.)

The nominal sensitivity for the iMM-6, given by Dayton, is -40 dB, where 0 dB = 1V/Pa. To convert that to V/Pa (to enter into SoundMeter), you need to raise 10 to the power of the sensitivity divided by 20. That is, 10^(-40/20) = 0.01 or 10 mV/Pa (which Dayton also gives as a nominal sensitivity). The sample file they provide has a sensitivity of -37.4 dB, which equates to a sensitivity of 10^(-37.4/20) = 13.49 mV/Pa, which you could enter into SoundMeter either as "13.49m" or "0.01349" (SoundMeter can recognize the "m" and format the number appropriately).

Keep in mind that you need to have the headset input device units set to "V" and the headset input channel units set to "Pa" in order for this to work. Also, you'll still have a nominal calibration. If you need a more accurate calibration, I would recommend performing a relative calibration against another sound level meter that you know has been accurately and properly calibrated. (I recommend this, regardless of which or whose iOS sound level meter app you are working with.)

Please let me know if you have questions about any of this.

Ben

15
SoundMeter / Re: Dayton Audio iMM-6 External Mic
« on: March 12, 2015, 10:40:03 AM »
Bruce,

Here's an excerpt from a recent blog post regarding SoundMeter's hardware support:
Quote
The new SoundMeter apps also support the Dayton UMM-6 USB measurement microphone. When the UMM-6 is detected, the user will be prompted to enter its serial number, which is typically printed on a label on the UMM-6. If a valid serial number is entered, SoundMeter will automatically download a calibration file from Dayton’s website and set the microphone sensitivity based on the information in the file.

Note: The Dayton UMM-6 must be connected to your iOS device via Apple’s USB camera adapter (either for Lightning or 30-pin dock connector, depending on your device). Sometimes the UMM-6 shows up in iOS as USB PnP Sound Device. If that happens, unplugging the UMM-6 and plugging it back in will generally solve the problem (it may take 2 or 3 tries). When properly connected, “UMM-6″ will appear as the input device name in SoundMeter’s toolbar (at the top of the screen).

This should work the same on any iOS device that runs the current version of SoundMeter.

Please let us know if you have other questions.

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