SoundScope Help Guide
This is the help guide for SoundScope on the iPhone, iPod touch, and iPad platform.
GUI
This section describes how to use the Graphical User Interface to operate SoundScope .
Split-screen (iPad
only)
Use the single/split control to select from a single screen or split screen. You can use the graph type buttons on the top and the bottom of the screen to select which graphs you would like to see in either window.
These gestures apply
to the RTA screens:
Double-tap to normalize the graph. This will expand the frequency scale to 20Hz – 20kHz, and auto-scale the dB axis to fit the current graph.
Swipe horizontally to move a cursor across the screen. The cursor will show the current dB levels at the selected frequency. In octave-band mode, the cursor will only stop at the center of the bands.
Pinch-zoom horizontally (use to fingers) to expand or contract the frequency scale. Once expanded, you can hold two fingers together and swipe horizontally to pan the frequency scale left and right.
Pinch-zoom vertically to expand or contract the dB scale. You can use a single finger to pan the dB scale up and down.
These gestures apply
to the Spectrograph screen:
When the spectrograph is running vertically, you can use a single finger to pan the graph down, so see activity that is in the history buffer. If the graph is in run mode, it will snap back to real time when you let go. If it is stopped, it will stay where you leave it. A scroll indicator appears on the side of the graph to show you how far you have moved into the history buffer.
Likewise, when the spectrograph is running horizontally, you can use one finger to slide the graph, showing the data from the history buffer on the screen.
Spectrograph &
Lines behavior
On the iPhone and iPod touch only, the RTA Lines display may be overlaid on top of the Spectrograph. In this case, the Spectrograph history function is only available when the graph is not running. When it is running, the normal RTA screen swipe gesture applies.
This section describes how to use the Real Time Analyzer, or RTA.
FFT Based
The SoundScope RTA is based on data obtained from running an FFT. The more points in the FFT, the more resolution you will get on the RTA graph, but the tradeoff is update speed. You can set the FFT size on the setup page, which is accessed by tapping the wrench icon. A good balance between resolution and update speed might be 8192 points. Note that some devices will run the FFT faster than others, so experiment to find what works best for you.
Graph Type
There are several graph types available:
RTA Bars – Octave-banded modes are displayed as bars on the screen.
RTA Lines – Frequencies are shown as a continuous line, with granularity to the selected octave band mode.
RTA & FFT – Octave-banded modes are displayed as bars on the screen, with the underlying FFT also shown.
Spectrograph – See Spectrograph description, below.
Spectrograph & Lines (iPhone and iPod touch only) – Adds the RTA Lines display on top of the Spectrograph.
Banding Mode
The banding mode determines how frequency data is shown on the screen. SoundScope uses ISO standard banding and frequencies. The available banding modes are:
Log -- Frequency is displayed logarithmically across the screen. In this mode, the display is always shown in line mode.
Lin – The frequency axis is linear, where the frequency axis midpoint is in the center of the screen. In this mode, the display is always shown in line mode.
Octave – The frequencies are grouped into octave bands. Note that in an RTA, any single frequency peak will push the entire band up.
1/3rd Octave – The frequencies are grouped into 1/3rd octave bands.
1/6th Octave – The frequencies are grouped into 1/6th octave bands.
1/12th Octave – The frequencies are grouped into 1/12th octave bands.
1/24th Octave – The frequencies are grouped into 1/24th octave bands.
1/48th Octave – The frequencies are grouped into 1/48th octave bands.
Decay
There are several decay modes available.
None – No decay, the display updates as quickly as possible.
1, 2, 4, 8, or 16 – In this mode, the FFT will be linearly averaged by the number selected.
1-10 seconds – This mode is an exponential decay. It is useful for acoustic analysis, since new data will rise quickly, but will then stay visible and decay more slowly.
Inf – (Infinite). This mode will continually average FFTs, for any length of time. Use it to gather a sonic signature over time. To reset the averaging, select it again.
Fast – ANSI / ISO Fast mode, with a time constant the same as an SPL meter set to Fast.
Slow -- ANSI / ISO Slow mode, with a time constant the same as an SPL meter set to Slow.
Overall dB Display
The overall un-weighted dB level is shown on the top of the screen. To show this in a larger font, tap the number. Tap the same location to make the number smaller.
The following items are set on the Setup page:
Peak Tracking
You can turn on peak tracking on the Setup screen. If on, the highest peak for the current banding mode will be displayed near the actual frequency on the screen. In large mode, it is shown in a large font in one location on the screen.
When you have recalled a stored graph, difference mode is available. It is turned on from the Setup page. When running, difference mode causes the stored the graph to be subtracted from the current graph, and the difference is shown on the screen, in dark green.
Audio Pass-Through
Turn this on to enable input audio to pass through to the output. Turning on the generator mutes the incoming audio.
Lock Graph Scale
Turn this on to prevent any changes from being made to the graph scale.
FFT Windowing
FFT windowing improves the quality and signal-to-noise ratio of the FFT. Three variants are available, Hamming, Hann, and Blackman.
This section describes how to use the Spectrograph.
A spectrograph is basically a way to visualize frequencies over time. In essence, the audio spectral response is shown as a line across the screen, where louder frequencies are shown in brighter colors. So, as the spectrograph runs, you can see a history of sound events as color blotches on the screen.
To use the Spectrograph, you will set a high and low limit for the dB levels that you are interested in visualizing. The dB levels are set by dragging the markers that appear on the right side of any of the RTA displays. To move these, use a two-finger vertical pinch gesture, at the right side of the screen. Horizontal lines will extend out across the screen from the indicators, while you are adjusting the levels. Normally, the levels are set so that normal background noise is not visible, and only sound events above a certain threshold are visible.
You can also choose whether you want the Spectrograph bars to move up the screen, or to move from right to left. This is set on the Setup page. Tap the wrench icon to access this page. To make the Spectrograph move up the screen, turn on Vertical Run. When you are running in this mode, the RTA frequencies will be aligned with the color bars on the Spectrograph.
Horizontal run can be useful to visualize speaker array coverage. Play pink noise, and walk across the sound field, in front of the array. The frequency response can now be seen as a function of distance. If the frequency response of the coverage pattern was perfectly uniform, the color blob would not change as you moved.
You can also adjust how fast the Spectrograph moves, which also effects the amount of information that is visible on the screen. This setting is also on the Setup page.
Also, SoundScope saves a real-time history of recent Spectrograph activity. To see part of the graph that has scrolled off the screen, just touch and swipe to pull it back on the screen. If the Spectrograph is running, it will snap back to real time when you let go. If you stop the Spectrograph (by tapping the Play/Pause button on the bottom of the screen), you can scroll back to previous activity and the graph will stay put when you let go. When you tap Play again, it will move to the most current info.
Note that the Spectrograph display will be cleared any time that the banding or graph type changes, or on the iPad, when you change the screen orientation. To prevent orientation changes from occurring, you can lock screen rotation. To do this, double-tap the iPad home button to bring up the multi-tasking bar, swipe right, and you will see the screen lock icon. Tap this to prevent the screen from rotating.
Also note that changing the frequency axis only changes new data that is being saved to the Spectrograph screen, previous data will not be re-graphed to the new frequency axis.
The octave banding mode also interacts with the Spectrograph display. Larger octave modes make for more smoothed Spectrographs, and smaller octave modes (like 1/12th -1/24th octave) make for more detailed displays.
Note that the Spectrograph is not effected by the RTA decay settings. It always runs with no decay.
The Save / Recall feature is accessed by tapping the tilted-square Ұicture frameӠicon on the bottom of the screen.
The functions are the same as those available from other modules in AudioTools, and include saving the raw FFT data to a tab-delimited text file, optionally storing GPS coordinates, a photo (for devices with cameras), and a notepad. Saved data can be synced to a computer over WiFi, by using the Utilities->Files function.
When recalled, the recalled graph appears in maroon color on the screen.
If a graph has been recalled, Difference Mode is available.
Tap the Sine icon to bring up the Generator Panel. This panel gives you basic signal generator control from the SoundScope screen.
On / Off
Turn the signal generator on or off using the switch.
Signal Type
Select the signal type by tapping the selector. You can select from sine wave, square wave, white noise, or pink noise signals.
Frequency
Set the frequency by moving the slider, or by tapping the frequency number to bring up a keyboard where you can enter an exact frequency value.
Sweep Control
You can start and stop the sweep generator from this screen. The sweep start and ending frequencies and sweep time are set on the main Generator screen (on the Utilities menu) in landscape mode.
To dismiss the Generator Panel, tap the sine icon.
White or Black
Spectrograph – If your spectrograph display is solid white, it indicates
that all of the sound coming in is above the upper
spectrograph marker is set too low. If the screen is all black, it means that
the lower marker is set too high. You can use a two-finger pinch on the right
edge of the screen to adjust them, or just double-tap the screen to set them to
a good starting position.
Fastest updates – To get the quickest updates on the screen, go with a small-to-mid size FFT, say 4096 or 8192, and turn off the spectrograph. Also, you will get the quickest response drawing a single graph, and by using one of the lower decay rates, like 2, 1 second, or Fast.
Quick Screen Scaling – Double-tap the screen to auto-scale both the frequency and dB axis.