Audio Precision has announced a new Android app for testing smartphone audio quality.
Serving as an interface between the Android device and one of Audio Precision’s APx audio analyzers, the app allows fast, automated profiling of new phones and tablets for network carriers, repair and refurbishment centers and other people who need to evaluate the audio performance of different models and manufacturers against a common standard.
AP’s Android app has four key features:
• Route audio through various analog signal paths not normally allowed by stock Android OS (for example, making a closed-loop test from analyzer to analog line-in to device’s speaker and back to analyzer)
• Use device’s record feature, then transfer the resulting file to an APx audio analyzer over USB for analysis
• Test Bluetooth signal paths, including the playback of stimulus waveforms over Bluetooth Handsfree Profile (HFP) without initiating a phone call over the network
• Automate the entire process with the APx desktop application to control the device over USB, allowing audio test sequences to run through all available signal paths with no user interaction required.
The ability to route analog audio through arbitrary inputs and outputs in loopback mode makes testing much faster than record and playback and enables real-time electroacoustic measurements. In addition, the default media player is bypassed, so there is no risk of user settings, EQ or resampling interfering with measurements.
The ability to open a SCO and send signals over Bluetooth HFP directly from the phone takes the mobile network’s audio performance out of the equation. The stock Android OS does not allow files to be streamed over HFP. The AP app overrides this behavior, allowing direct evaluation of the Bluetooth connection quality independent of the mobile network (the weakest link in the signal chain).
The AP Smartphone App for Android supports sine, continuous sweep and multitone signals for music playback signal paths. For voice band, AP recommends using PESQ or POLQA MOS (mean opinion score) perceptual audio measurements, which are fully supported by the AP smartphone app and are incorporated in the accompanying APx project files and test waveforms. The app supports all APx supported profiles and codecs: A2DP (with SBC and APTx codes) and HFP/HSP (with CVSD and mSBC wideband voice codecs).
The new desktop app and accompanying APx project files allow all the testing to be automated, significantly reducing test time, and minimizing the opportunity for operator error.
The APx Smartphone app is available for download at the AP.com website at no charge as part of Technote 120. The app requires Android version 4.0 and higher and a connected APx audio analyzer to function.
