SignalScope Pro 4 for iOS uniquely identifies USB audio devices

SignalScope Pro version 4 can uniquely identify USB audio devices attached to iPhone, iPod touch, or iPad, and remember user settings for each device the next time it is connected. Direct support has been added for The Modal Shop’s model 333D01 USB digital accelerometer and miniDSP’s UMIK-1 USB measurement microphone. With the 333D01, SignalScope Pro automatically loads serial number and sensitivity calibration information directly from the device as soon as it is connected. When the UMIK-1 is connected, SignalScope Pro recognizes it and prompts the user for its serial number. Sensitivity calibration and frequency response data for the UMIK-1 can then be downloaded automatically, just by entering the UMIK-1’s serial number.

Another major new feature in version 4 is SignalScope Pro’s ability to load microphone frequency response data (FRD) and apply frequency response correction (FRC) to FFT spectrum measurements. FRD can be loaded for any input channel, for any kind of transducer (i.e. it’s not just for microphones). Sophisticated interpolation techniques are employed to generate a smooth frequency response
correction curve that matches the loaded data. This correction curve can then be applied to an FFT spectrum
of arbitrary length or frequency resolution.

SSP4 Accel and Mic

Also new in version 4:

– SignalScope Pro directly supports The Modal Shop’s model 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. Factory calibration information is embedded in exported audio files (from the Oscope tool) when data is acquired with the 333D01.

– SignalScope Pro directly supports the miniDSP UMIK-1 USB measurement microphone. Sensitivity calibration and frequency response data for the UMIK-1 can be downloaded automatically, just by entering the UMIK-1’s serial number. Making calibrated sound level measurements is as easy as plugging in the UMIK-1 and typing in its serial number (the serial number only needs to be entered once, after which SignalScope Pro will remember the microphone sensitivity).

– Additional dB scales of 3, 6, 12, 15, and 18 dB per div are now supported by the FFT analyzer. Also, when adjusting the dB scale manually, the dB offset will always be set as a multiple of the scale so that 0 dB is always available in the vertical axis labels.

– Minor bug fixes and cosmetic enhancements.

– Apple’s Lightning to USB Camera Adapter or iPad Camera Connection Kit is required for connecting USB Audio devices to your iPhone, iPod touch, or iPad.

– SignalScope Pro 4 requires iOS 7 or later.

Similar features have been added to SignalScope 5.0, although select in-app upgrades may be required (available via in-app purchase).

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Looking for the best sound level meter app

Last year, researchers at NIOSH (the National Institute for Occupational Safety and Health) began looking at mobile sound level meter apps, hoping to find that such apps could be suitable for occupational noise measurements. After defining specific criteria to qualify sound level meter apps as suitable for their tests, they set out to find matching apps for  iOS, Android, and Windows-based mobile devices. Ten iOS apps, out of over 130 available, were examined as part of their research. Of 62 Android apps downloaded for examination, only 4 apps partially met their criteria. No Windows-based apps qualified.

The results of the study were recently published in the Journal of the Acoustical Society of America (JASA). According to the published article, “The evidence suggests that for A-weighted data, SoundMeter is the app best suited for occupational and general purpose noise measurements. In addition to having the smallest mean difference for the A-weighted data, SoundMeter had the narrowest distribution of differences…”

SoundMeter Screenshot iPhone 5

The article concludes, “This study showed that certain sound measurement apps for Apple smartphones and tablets may be considered accurate and reliable to be used to assess occupational noise exposures. Android and Windows developers do not offer apps that meet the functionality needed for occupational noise assessments.”

Download SoundMeter

Download SoundMeter Pro

Noted at the end of the article: “The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health. Mention of any company or product does not constitute endorsement by NIOSH.”

JASA Article

NIOSH Blog Article (with images and video)

 

Faber Acoustical announces SoundMeter Pro for iOS

Building on the success of SoundMeter, which debuted on the iPhone App Store in August of 2008, Faber Acoustical has announced the release of SoundMeter Pro. SoundMeter Pro turns your iPad, iPhone, or iPod touch into a handheld data-logging sound level meter (SLM), data-logging noise dosimeter, and real-time analyzer (RTA).

SoundMeter Pro works with built-in or external measurement microphones to deliver reliable sound level measurements, including time-weighted and equivalent sound levels in addition to percentile-exceeded sound levels and noise dose. Measured levels can be logged at intervals as small as 0.1 seconds for durations of up to two weeks (longer measurement durations may require larger logging intervals). The built-in Octave tool performs sound level measurements in whole or 1/3-octave frequency bands.

In a recent article published in the Journal of the Acoustical Society of America, NIOSH researchers found that, out of over 130 sound measurement apps for iOS, “SoundMeter is the app best suited for occupational and general purpose noise measurements.” SoundMeter Pro builds on everything SoundMeter has to offer.

With the built-in or headset microphone, SoundMeter Pro can measure peak sound levels of up to approximately 130 dB. Results may vary between iOS devices and headset microphones. External microphones may enable the measurement of much higher sound levels.

SoundMeter Pro also includes various features that users have come to expect from Faber apps, including the ability to save measurement data to CSV, TXT, or MAT files, save measurement displays to high resolution PDF files, switch between three different color schemes, and calibrate microphone input sensitivity. Exported data files may be retrieved from the iOS device via iTunes File Sharing or by enabling the app’s built-in file server and downloading the files to another device or computer via a standard web browser. The built-in signal generator tool further extends SoundMeter Pro’s utility by producing any of various test signals, including white noise, pink noise, frequency sweeps, and periodic waveforms.

Faber Acoustical has simultaneously announced the availability of SoundMeter 5.0. The new version of SoundMeter adds support for a new Data Logging Upgrade, which is available via in-app purchase. SoundMeter Pro includes all the functionality of SoundMeter 5 with all its available in-app purchase upgrades. Although both apps run on iOS 6, each also features a user interface tailored for iOS 7.

NOTE: Although it has been designed to do so, SoundMeter Pro is not guaranteed to meet ANSI or IEC standards for sound level meters. These standards require conformance of the entire measurement system, including software, hardware and microphones.

The built-in and headset microphones are suitable for certain, basic sound level measurements, but high precision external microphones may also be used with appropriate audio accessory hardware. Even though default sensitivity values are included for the built-in and headset microphones, for best results, SoundMeter Pro should be calibrated before use. Sound levels may be off by a few dB when using the default microphone sensitivity.

   SoundMeter Pro Screenshot iPhone 1 SoundMeter Pro Screenshot iPhone 2

   SoundMeter Pro Screenshot iPhone 3 SoundMeter Pro Screenshot iPhone 4

 

Minimum Requirements:
* iOS 6.0 or later
* iPhone, iPod touch, or iPad
* 4.12 MB

Pricing and Availability:
SoundMeter Pro is now available for download on the App Store for $99.99 (USD). External hardware may be required for analog input capability. More information on SoundMeter Pro can be found at Faber Acoustical online. More information regarding suitable input devices for specific iOS devices can be found on the Faber Acoustical blog.

Download SoundMeter Pro

Download SoundMeter 5.0

SoundMeter and dB support new iPads

Nominal microphone sensitivities for the iPad Air and iPad mini with Retina display have been added to SoundMeter 4.0.1 and dB 3.0.1.

Both apps also display dark blue toolbars in the black color scheme to make it easier to view the screen in dark environments.

SoundMeter additionally corrects the HTTP file server configuration screen, which now scrolls to reveal the web URL on 3.5-inch iPhone screens (the file server is available for in-app purchase as part of the data acquisition upgrade).

SoundMeter Screenshot iPhone 5

 

SoundMeter 4.0.1 and dB 3.0.1 are both available for download on the App Store.

Download SoundMeter

Download dB

 

Pop those balloons with RoomScope 1.3

A common request for RoomScope has been to directly capture room impulse response (IR) data using impulsive noise sources, such as balloons or starter pistols. RoomScope 1.3 now supports both single-channel and dual-channel IR data acquisition. The dual-channel capability has been built-in since version 1.0 of RoomScope, enabling the use of an omnidirectional loudspeaker and various excitation signals including broadband noise and frequency sweeps. The new single-channel IR acquisition tool can capture IR data directly by popping a balloon or firing a starter pistol within an acoustic space of interest. The input signal can be triggered in order to automatically begin data acquisition when the instantaneous input level crosses a user-defined threshold.

It should be noted that single channel analysis doesn’t mean that only one channel of data can be captured at one time. In fact, with an iPad and a multi-channel USB audio interface, it is possible to capture IR data from multiple microphones simultaneously (obviously, the mics and supporting cables, adapters, etc, would also be needed). Single channel analysis simply means that each input channel is treated independently from all other input channels. In contrast, dual-channel analysis means that a single measurement is based on data acquired from two input channels (using auto and cross-spectral analysis).

RoomScope 1.3 is now available for download on the App Store.

RoomScope 1.3 Screenshot

Download RoomScope 1.3

Are you looking for a measurement microphone for your iPhone?

Since iOS 6 finally remedied the low frequency roll-off problem of the headset mic input of the iPhone, iPod touch, and iPad, the headset jack has become a suitable option for measurement microphone input. Prior to the release of iOS 6, the only way to connect an external measurement microphone, without sacrificing low-frequency information, was to go through the dock connector. Dock connector devices can still provide higher quality solutions, but working with the headset jack offers a level of portability (i.e. compact size) that cannot be matched when a 30-pin dock connector is involved (we’ll see what comes along to take advantage of the new Lightning connector).

MicW i436

Some time ago, I was made aware of the i436 measurement microphone from MicW. It looked like exactly what was needed to turn any iOS device into a quality sound level meter, or acoustical analysis tool, that you could truly carry around in your pocket. However, it was limited in its utility by that pesky low-end roll-off that plagued earlier versions of iOS. Some developers attempted to perform software correction for the input filters, but when an input signal is driven into the noise floor by the hardware (or firmware), there’s nothing app software can do to restore the lost signal at those lower frequencies. Now that iOS 6 has solved the issue, the i436 has become the attractive measurement microphone solution for iOS that it should have been when it was first introduced.

i436i436

Last weekend, I carried the i436 around the Denver Tech Center Marriott at the Rocky Mountain Audio Fest (RMAF), along with my iPhone 5. The i436 is small enough that it could slip into my pocket and remain there unnoticed or it could stay connected to the iPhone, which was perched in my shirt pocket when it wasn’t in my hand. In short, I was quite pleased to confirm that the i436 does indeed make for a portable measurement solution that you can carry in your pocket all day long.

MicW i436 Noise Measurement

As for quality, the i436 looks and feels like a proper measurement microphone. It was designed to meet the Class 2 standard for sound level meters, which addresses issues like environmental stability in addition to frequency response. The i436 also fits a standard microphone field calibrator, with a 1/4″ adapter, which you would also expect from a measurement microphone. A field calibrator makes microphone sensitivity calibration very easy with measurement software like SoundMeter or SignalScope Pro.

i436 Typical Frequency Responsei436 Typical Polar Pattern

The i436 is available in a package with just the mic, or in a kit. The kit includes a wind screen, extension cable, splitter cable (to connect headphones or an audio cable to the headphone output), a small clip, and an aluminum storage tube that doubles as a holder for the i436 that mounts to the top of a standard microphone stand (very handy).

i436 Single Packagei436 Kit Package

If Class 2 compliance meets your needs, then I highly recommend the MicW i436, especially in the kit. Either option is quite affordable for a quality measurement microphone. If you need a microphone that conforms to the Class 1 standard, then another hardware solution will be necessary.

iPhone 5 audio consistent with iPhone 4S

Today, I had the opportunity to begin testing the audio input characteristics of the new iPhone 5. As seen in the plots, below, the headset input frequency response matches that of the iPhone 4S, which was presented in the previous post. The behavior of the built-in microphone also seems to match that of the iPhone 4S, suggesting that Apple kept the audio input path essentially unchanged in the new device.

One current limitation of the iPhone 5 is that existing dock connector accessories for audio input (and output) are not compatible, due to the iPhone’s new Lightning connector. As soon as Apple’s new Lightning to 30-pin adapter arrives, we’ll be able to see if it enables existing audio accessories to work with the new iPhone. Until then, the headset input and built-in microphone will have to suffice for iPhone 5 users. Fortunately, iOS 6, which comes installed on the iPhone 5, allows us to bypass automatic gain control and the high pass filter that plagued the headset input and built-in mic in earlier versions of iOS.

iPhone 5 Headset Leq iOS 6

iPhone 5 Headset Leq iOS 6 Fine Scale

Finally! iOS 6 kills the filter on headset and mic inputs!

So, iOS 6 has finally arrived and the biggest news for SoundMeter, SignalScope, and SignalScope Pro users may just be that the high-pass filter which used to plague the built-in microphone and headset microphone inputs now gets bypassed. This exciting improvement to iOS 6 will significantly improve the quality of acoustical measurements that can be made with the iPhone, iPad, or iPod touch, without requiring a dock connector accessory for audio input.

Below are 1/3-octave headset input frequency response comparisons for the various iOS devices that support iOS 6. More details regarding the headset input and built-in microphone will be presented in the days ahead.

Update (9/19/20120, 7:32 PM): It should be noted that these are electrical frequency response measurements. When making acoustical measurements, the overall frequency response will depend also on the microphone that is used.

iPhone 4S Before iOS 6/Now

iPhone 4S Headset Leq Pre-iOS 6  iPhone 4S Headset Leq iOS 6

iPhone 4 Before iOS 6/Now

iPhone 4 Headset Leq Pre-iOS 6  iPhone 4 Headset Leq iOS 6

iPhone 3GS Before iOS 6/Now

iPhone 3GS Headset Leq Pre-iOS 6  iPhone 3GS Headset Leq iOS 6

iPod touch 4 Before iOS 6/Now

iPod touch 4 Headset Leq Pre-iOS 6  iPod touch 4 Headset Leq iOS 6

iPad 3 Before iOS 6/Now

iPad 3 Headset Leq Pre-iOS 6  iPad 3 Headset Leq iOS 6

iPad 2 Before iOS 6/Now

iPad 2 Headset Leq Pre-iOS 6  iPad 2 Headset Leq iOS 6

 

iOS 6 is now highly recommended for all SoundMeter, SignalScope, and SignalScope Pro users.

 

 

iPhone 4 Audio and Frequency Response Limitations

The iPad’s lack of line level audio input support via the dock connector certainly raised the question of what would be in store for the iPhone 4. Now that I have my hands on the new iPhone, I thought I would go ahead and report on the state of audio I/O on the new device.

Here’s what seems pretty clear, based on my initial tests of the iPhone 4:

  • The iPhone 4 does not accept standard iPod accessories with line level input
  • Unfortunately, the new iPhone doesn’t work with the USB connector of the iPad camera connection kit, either, so there really isn’t a two-channel audio input option at the present time.
  • The frequency response of the iPhone 4’s headset mic input is virtually identical to that of the iPhone 3GS.
  • The built-in microphone’s frequency response also closely matches that of the 3GS.

iPhone 4 Headset Input Frequency Response

iPhone 4 Built-in Microphone Frequency Response

It really is unfortunate that there is currently no way to get stereo signals into the new iPhone 4, although I’m confident that it’s only a matter of time before an acceptable solution presents itself. Beyond this glaring limitation, the iPhone 4 is essentially the same as the iPhone 3GS (and iPad) in terms of its audio performance. It will be interesting to see, though, what new possibilities open up with the A4 processor, the increased memory, and the high-resolution display (which is quite amazing, by the way).

USB Audio Devices that work with iPad

The discussion of issues surrounding the iPad’s USB audio support in the previous post certainly begs the question, “Which devices work properly with the iPad?” In the table below, I list the devices I have tested with the iPad, along with some observations.

iPad USB Audio Device Compatibility

Please keep in mind that the iPad Camera Connection Kit is required to connect USB audio devices to the iPad (see the previous post).

Input Output Bus Power Notes
ART USB Dual Pre Data Loss (1) Works (2) Yes The USB Dual Pre runs on bus power, even with phantom power on. It can also run on a 9V battery.
Behringer UFO202 Data Loss (1) Works (2) Yes
Blue Icicle No N/A N/A The iPad completely rejects the Icicle with the message: “The attached USB devices is not supported.”
Griffin iMic Works Works Yes I tested an older model, but others have confirmed that the newer model also works.
MXL Mic Mate Classic Data Loss (1) N/A Yes (3) Phantom power is always on. No output channels.
MXL Mic Mate Pro Data Loss (1) Works (2) No Phantom power is always on. A self-powered USB hub is required to use the Mic Mate Pro with the iPad.
Nady UIM-2X Works Works Yes (3) Unfortunately, the UIM-2X rolls off low frequencies, below 200 Hz, which makes it undesirable as a measurement device.
  1. Input data reaches the iPad, but it gets corrupted, apparently because of improper clock synchronization.
  2. Audio output works fine, as long as the iPad app does not also retrieve input data. For example, the ART USB Dual Pre works fine with SignalSuite, which only uses audio output. The same device produces audible glitches in its output when used with SignalScope Pro, which uses the device’s input and output channels.
  3. If the input device draws too much current, the iPad will refuse to work with it, even if the iPad had already been working with the device. For example, even though the Nady UIM-2X presents itself as a high power device (one that requires more than 100 mA of current from the USB bus), the iPad will work with it until you turn the UIM-2X’s phantom power on. At that point, the iPad will indicate that it draws too much power and switch audio back to the internal mic and speaker.

In summary, of the devices mentioned above, only the Griffin iMic and Nady UIM-2X work properly for both audio input and output with the iPad. Audio output generally works on output-capable devices, although some devices produce audible glitches when both input and output are used by an iPad app. Unfortunately, there still isn’t a simple, bus powered solution for connecting a phantom-powered measurement microphone to the iPad.

Feel free to share your iPad USB audio experience in the comments.

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