1Android Audio Quality Verifier App 2================================== 3 4This app runs a set of audio quality tests on an Android device, 5to verify the end-end sound recording path. 6 7If any of these tests fail, the device is probably unsuitable 8for demanding audio tasks such as speech recognition. 9If all the tests pass, the device audio is of a good standard. 10Note that not all possible audio defects can be detected by this 11test suite, so passing does not guarantee ideal audio quality. 12 13Hardware setup 14-------------- 15 16The required physical set-up consists of a powered speaker, 17connected to the Android's headphone output by a standard 18audio cable. 19 20For loudspeakers which come in pairs, you only need to use 21one speaker (typically the powered or master speaker); you 22can leave the second speaker disconnected. 23If the speakers are stereo within a single unit (sometimes 24with speakers facing in opposite directions), place the phone 25in front of either of them. 26Speakers with multiple drivers per channel (e.g. a tweeter 27and a woofer) are not suitable. 28 29The phone should be placed in front of the centre of the 30speaker cone. The distance from the speaker will be adjusted 31during calibration; typically you could expect it to be around 323cm or so. 33Use a supporting platform such as a stack of books to raise 34the phone to the correct height to line up with the speaker. 35 36Bluetooth connection is possible but cable connection is 37usually preferable. 38 39Recommended loudspeakers 40------------------------ 41 42Using suitable loudspeakers ensures that test failures highlight 43problems with the Android device under test, and not limitations 44of the loudspeakers. The following loudspeakers work well for this 45purpose: 46 471. Yamaha NX-B02 48 49Use on AC power, not batteries. 50This speaker works well with Bluetooth as well as a wired connection. 51Note that it's not uncommon for the devices to exhibit different 52bugs under Bluetooth. 53 542. Cakewalk MA-7A (Edirol / Roland) 55 56The "Bass Enhancer" feature MUST be switched off. 57Note that it turns itself on again every time the speakers are 58powered on, so it is easy to forget to switch it off! 59 60Software setup 61-------------- 62 631. Build the application's apk. 642. Install the apk using adb. 653. Run the app. 664. Click "Calibrate". Position the phone as described in 67 Hardware setup above, with the microphone facing the speaker, 68 and adjust the volume of the speaker until the status message 69 indicates it is correct. 705. Click on any test in the list to run it, or "Run All" to run 71 each test in sequence. 726. Click "Results" to view the outcomes. A correctly functioning 73 device should pass all tests. 747. Click "Send by email" from the results page to send the 75 results to an e-mail address of your choice. The recordings 76 made are also attached as raw 16 bit, 16 kHz audio files to 77 help you diagnose any failed tests. 78 79Q&A 80--- 81 82Q. What if the sound level check fails? 83A. Go back to the calibration step before running any other test. 84 Make sure the device has not been moved. 85 We also recommend that once the setup is calibrated there are no 86 moving objects or people near the device under test, since these 87 will change the acoustic properties of the environment from the 88 calibrated state. 89 90Q. Some of the tests sound very loud. Is this normal? 91A. The clipping test will generally be very loud indeed; 92 the others should be at a moderate volume. 93 94Q. What sort of room should the tests be performed in? 95A. Any, as long as the background noise levels are kept low, to 96 avoid interference with the test recordings. 97