The Faber app updates released this week address the issue with the built-in iPad microphone input gain. In short, with the release of iOS 9.3.1, Apple chose to change the input gain range for the built-in microphone on iPad, which meant that apps such as SoundMeter needed to either adjust input gain or input sensitivity in order to continue to allow for reasonably accurate sound level measurements. Unfortunately, iOS versions 9.3.1 through 9.3.4 contain a bug that causes the previous input gain range to be applied after a microphone is connected to the headset jack and then removed.
The following Faber apps have been updated with a built-in workaround to properly apply the appropriate input gain on each version of iOS:
Electroacoustic’s Toolbox 3.8.3 can now be downloaded from the Mac App Store and from FaberAcoustical.com.
New in version 3.8.3:
An issue with channel sensitivity adjustments in the Meter Bridge and Sound Level Meter tools has been addressed.
When loading Room Analyzer tools from a project file, if a permissions error occurs for an audio file being used for analysis, an Open dialog will be presented with the file in question selected. Once the file is then manually loaded via the dialog, the permissions will be properly set for the next time the project is loaded. This is an issue with sandboxed copies of Electroacoustics Toolbox downloaded from the Mac App Store.
The Room Analyzer tool’s plotting is more reliable when loading the tool from a project file on recent versions of Mac OS X.
SignalScope Pro for Mac has also been updated with the same improvement to the Meter Bridge and Level Meter tools.
The FFT-based spectrum analyzer in SignalScope Pro 6.2 allows arbitrary upper and lower frequency bounds (Fmax and Fmin) to be specified for the spectrum display. The cursor peak track function will operate only within the specified frequency bounds. The hardware sample rate may optionally be automatically adjusted to best match the specified value for Fmax.
A typical minimum sample rate of iOS hardware is 8 kHz. If a frequency resolution of 1 Hz is used for the spectrum, and values of 10 and 400 are specified for Fmin and Fmax, respectively, the data between 10 and 400 Hz will be plotted and the plot will be scaled to extend only from 10 and 400 Hz. If the cursor peak track function is enabled, the cursor will find the frequency of the highest magnitude between 10 and 400 Hz.
If the option to automatically adjust the sample rate based on Fmax has been selected, the hardware sample rate (Fs) will automatically be reduced to the minimum rate required to acquire data up to 400 Hz. In the case of typical iOS or USB audio input hardware, this rate would be 8 kHz. Since FFT data would then include values between 0 and 4 kHz, an additional option allows either all data (0 to 4 kHz) or only data from 10 to 400 Hz to be exported when saving FFT data to a CSV, TXT, or MAT file. Note that the DC term may be omitted from exported data when FFT data is displayed on a logarithmic frequency scale.
Also new in SignalScope Pro 6.2:
When “cpm” is selected for units of frequency, exported data files will include frequencies specified in cpm.
The nominal microphone sensitivity is properly set on the new iPhones.
Other bug fixes/stability enhancements, including iOS 9 compatibility.
Similar improvements have been added to version 7.2 of SignalScope. Specifying values for Fmin and Fmax in SignalScope require the Data Acquisition Upgrade, which is available via in-app purchase.
SignalScope Pro 6.1 and SignalScope 7.1 have been released for sale on the App Store with some important enhancements, including the ability to mix audio output with other apps. Audio mixing means that it is possible to play music from the Music app while performing signal analysis with SignalScope or SignalScope Pro. It is also possible to mix the output of the signal generator* with the audio output from another app.
The SignalScope apps include other important enhancements:
The FFT analyzer tool now supports frequency resolution as fine as 0.1 Hz for audio input signals.
When working with an iPhone or iPad that has multiple built-in microphones, the unique name of the selected microphone is displayed (e.g. “Bottom Microphone” or “Right
When analyzing two input channels in the Octave tool, both spectra are displayed in a single line plot.
Although Faber Mac and iOS apps have offered excellent sound and vibration analysis tools from the start, the introduction of the Digiducer 333D01 USB Digital Accelerometer makes vibration measurement easier and more portable. When the 333D01 is connected to a Mac, iPhone, or iPad, it will be immediately recognized by our apps and ready for calibrated measurements.
For example, SignalScope Pro will recognize the connected 333D01 as an accelerometer and set the measurement units accordingly. SignalScope Pro will also automatically read calibration information from the 333D01 and establish the appropriate sensitivity so calibrated measurements can be made immediately. This works with both the Mac and iOS versions of SignalScope Pro.
The 333D01 communicates with Mac OS or iOS via the standard USB Audio Class driver. Connecting to a Mac is as simple as plugging the 333D01’s cable into an available USB port. For iOS, Apple’s Lightning to USB Camera Adapter is required.* When connecting to iOS, no additional power source is required, which makes Faber apps and the 333D01 part of an ultraportable vibration measurement system.
If you’re looking for a way to acquire stereo input signals in apps like SignalScope Pro or IOScope, you’ll be pleased to know that you can connect a USB audio device to your iPhone, iPad, or iPod touch via Apple’s Lightning to USB Camera Adapter. Built-in USB audio support in iOS opens up a vast array of options for getting audio signals into, and out of, your iOS device. (USB audio support on iPhone and iPod touch requires iOS 7 or later.)
The trick is to find a device that conforms to the USB Audio Device Class specification, which essentially means that no special drivers are required when connecting the device to a host, like a Mac or an iPhone. Some device manufacturers clearly state that their product works with iOS and some do not. In general, if you find a USB audio device that does not require special drivers to work with Mac OS, then it will work with iOS as well.
One thing to consider when selecting a USB audio device to connect to your iPhone or iPad is power. Some USB audio devices require an external power source, which means portability will be somewhat limited due to the need to have an A/C power outlet nearby. Other devices support USB bus power, which means they’ll draw their power from the host device (e.g. the iPhone). For portability, this would be the ideal situation since the iPhone and input device could be completely portable and operate for the life of the iPhone’s battery. However, only low-power devices can be directly powered by an iPhone or iPad, which means that a lot of otherwise compatible USB audio devices cannot be connected to iOS without some other source of power. For bus-powered USB devices that require more power, it is possible to maintain some portability with a USB battery power supply and an additional adapter cable.
A Few Examples (portable and inexpensive)
Stereo USB Audio Devices
The UCA202 from Behringer offers very inexpensive and portable stereo input for iOS.
16-bit/48 kHz sampling
2 inputs and 2 outputs with RCA jacks
Headphone output with volume control (1/8″ jack)
Low power operation so it can be powered directly by an iPhone or iPad
This adapter is all that’s needed to connect a compatible USB audio device to an iPhone, iPad or iPod touch with a Lightning connector. As indicated above, if your USB device needs additional power, additional components will be needed. That will be discussed in a separate article.
Faber Acoustical is pleased to announce that a live Spectrogram tool is now available for purchase within SignalScope and SignalScope Pro. The Spectrogram tool is offered in both 2D and 3D versions. The 3D Spectrogram includes all the functionality of the 2D version and adds powerful hardware-accelerated 3D plotting capabilities including a live 3D surface plot. A 3D upgrade is available to those who opt to purchase the 2D version.
The real-time Spectrogram plots FFT-based spectral data versus time in a colorful surface plot. Signal magnitude at each time and frequency is represented by color. Use single-finger tap and drag to place a data cursor within the plot. When the cursor is visible, details regarding time, frequency, and magnitude will be displayed above the plot.
Main Features (available in both versions of the Spectrogram tool:
Frequency resolutions between 1 Hz and 50 Hz, depending on sample rate, may be specified for audio input (between 1 Hz and 10 Hz for the built-in accelerometer).
Input data can be windowed with one of 7 different FFT data window types.
Spectrogram data can be captured over time periods ranging from 2 to 20 seconds.
Lin, log, and dB magnitude scales with Up, Down, or Full auto-scaling.
Lin and log frequency scales.
Fractional-octave band frequency smoothing in 1/6, 1/12, and 1/24-octave bands.
Cursor peak track can track peaks in time, frequency, or both.
Color scale bar graph enables manual adjustment of magnitude scale and offset. The color scale can also be hidden.
Data may be exported to CVS, MAT, or TXT files for post processing or plotting. Optionally, include GPS location information with exported data. (The data export option is included in SignalScope Pro. It requires the Data Acquisition upgrade, sold separately, in the standard version of SignalScope.)
Optionally save a high-resolution PDF file of the spectrogram plot, or save an image to your Photos library.
3D Spectrogram Features:
Choose between 2D and 3D surface plots. Each plot can be drawn live (in real time).
Trackball-style 3D rotation of the 3D surface plot, just by dragging a single finger across the plot.
Tap with a single finger to place a cursor within the 3D plot.
In 3D, the cursor outlines the time and frequency slice associated with its current location.
Optional grid planes for each axis (magnitude vs. frequency, magnitude vs. time, and frequency vs. time) are drawn at the bounds of the 3D plotting region.
By default, the 3D spectrogram is drawn as a surface and magnitude values are represented by both position and color. The surface can be turned off, which allows data to be drawn only as a mesh.
The 3D spectrogram data can be seen as a solid-colored mesh (the mesh draws nothing between its lines or points). The mesh can be overlaid on the surface or drawn alone.
The mesh can be drawn as lines in time, lines in frequency, or lines across both time and frequency. It can alternatively be drawn as a series of dots, each one representing a single spectrogram data point.
When only viewing the 3D spectrogram data as a mesh, the time and frequency slices outlined by the cursor show through the mesh, making it very easy to see them in the midst of the rest of the data.
Also new in SignalScope and SignalScope Pro:
GPS coordinates, altitude, and accuracy may now optionally be saved with FFT, Spectrogram, or Oscope data when exporting to a data file (Data Acquisition Upgrade required in SignalScope).
Downloaded frequency response data for connected microphones will automatically be saved in a file in the Frequency_Response_Data folder to make it easier to access at a later time.
Smarter selection of the maximum frequency when FFT data smoothing is enabled.
Fixed an issue with Full Autoscale in the FFT analyzer.
Versions 3.8 of SignalScope, SignalScope Pro, and Electroacoustics Toolbox for Mac OS now offer built-in support for USB measurement microphones from miniDSP and Dayton Audio as well as the model 333D01 USB accelerometer from Digiducer.
Each app directly supports the miniDSP UMIK-1 and Dayton UMM-6 USB measurement microphones. Sensitivity calibration data for these mics can be downloaded automatically, just by entering the mic’s serial number. Making calibrated sound level measurements is as easy as plugging in the UMIK-1 or UMM-6, typing in its serial number, and getting started with the analysis tool of your choice (the serial number only needs to be entered once, after which the app will remember the microphone sensitivity). An internet connection is required to download sensitivity information for the microphone.
Each of these apps also directly supports the Digiducer 333D01 USB digital accelerometer, and can automatically load serial number and sensitivity calibration information directly from the device. Making calibrated acceleration measurements is as easy as plugging in the 333D01 and getting started with the analysis tool of your choice.
Various bugs and potential instabilities in each app have been corrected.
These apps all require Mac OS version 10.7 or later.
SignalScope Pro 5.0 and SignalScope 6.0*, both now available for download on the App Store, add support for up to 7 FFT spectrum curves to be loaded from existing data files (CSV, MAT, or tab-delimited text files previously saved from the FFT analyzer tool). Live FFT data can be overlaid on these curves. When loaded data files include multiple channels of FFT data, one or more of those channels can be selected for display in the current FFT plot. The addition of controls for adjusting the line thickness and opacity of loaded data makes it easy to visually distinguish between live and static FFT data. The FFT analyzer also now supports fractional-octave band smoothing of curves displayed in the plot. (It is important to note this is simply smoothing of the FFT curve—it does not simulate the behavior of true fractional octave band filtering, such as that offered by the Octave analyzer tool, which is included in SignalScope Pro.)
The Octave analyzer tool** also now offers the option to load whole or 1/3-octave spectrum data from data files. Up to six curves can be overlaid on the live bar graph. Again, it is possible to select the individual channels from which to load data when multiple channels of data exist within a single file.
Another significant addition to SignalScope and SignalScope Pro is direct support for iTestMic and iAudioInterface2 hardware from Studio Six Digital, as well as the Dayton UMM-6 USB measurement microphone. The new hardware support is consistent with the additions made to SoundMeter Pro 2.3.
Also new in SignalScope Pro:
SignalScope Pro 5 employs a new plotting framework for real-time data graphs and high resolution image export.
The black color scheme now uses black status bar, toolbar, and tab bar backgrounds.
Support for drawing directly to an external screen (from iPad) has been removed in favor of screen mirroring, which is handled by iOS.
Audio hardware input and output options are now presented from a separate toolbar button, which looks like a microphone, on iPad, iPhone 6 and iPhone 6 Plus.
It is possible to adjust the line thickness of live and loaded frequency response data. The opacity of loaded data can also be adjusted in order to make the live data stand out in the graph.
The oscilloscope time scale can now be set from the oscilloscope options menu.
Saving an audio file no longer causes a crash when working with large oscilloscope time scales.