SMARTPHONE AS NOISE LEVEL METER? Jacopo Fogola, Stefano Masera, Vincenzo Bevacqua Environmental Protection Agency - Piedmont Region, Turin, Italy

Transcription

1 SMARTPHONE AS NOISE LEVEL METER? Jacopo Fogola, Stefano Masera, Vincenzo Bevacqua Environmental Protection Agency - Piedmont Region, Turin, Italy

2 OBJECTIVES 1. To study accuracy and precision of environmental noise measurements through smartphones 2. To investigate the possibility of using other low cost devices

3 SMARTPHONES AND APPS SMARTPHONES GT-B5330 (Android v.4.0.4) 2.Samsung Advance GT-I9070P (Android v.2.3.6) 3.HTC Desire 601 (Android v.4.4.2) 4.iPhone 4S (ios v.8.0.2) 5.iPhone 5S (ios v.8.1.3) Noise Meter (Android) APPS Noise Immission Analyzer (ios)

4 NOISE METER FOR ANDROID Sampling frequency adjustable: 8000, 11025, 22050, 44100, Hz 1 db steps gain, in the range db Integration period from 1 sec to 10 minutes Events detection Digital filters: low-high-band pass, A ponderation Data capture: peak, minimum, maximum, arithmetic average, energetic average (equivalent level) Data storage in a txt file NO frequency spectrum

5 NOISE IMMISSION ANALYZER FOR IOS Sampling frequency: Hz Calibration with a known signal Digital filters: A-B-C-linear ponderation, fast, slow Data capture: minimum, maximum, energetic average (equivalent level) Audio file record up to 20 seconds

6 LABORATORY MEASUREMENTS Comparison of the response to white noise at different SPL with a class 1 sound level meter

7 LABORATORY MEASUREMENTS Internal microphone Sm artphones - db(a) iphone 5s iphone 4s 105 HTC Sam sung Advance 95 Sam Professional sound level meter - db(a)

8 LABORATORY MEASUREMENTS Headphones with microphones S m artphones - db(a) iphone 5s iphone 4s 105 HTC Sam sung Advance 95 Sam s Professional sound level meter - db(a)

9 LABORATORY MEASUREMENTS Class 2 external microphone (MicW i436) Smartphones - db(a) iphone 5s 105 iphone 4s 100 HTC Professional sound level meter - db(a)

10 OUTDOOR MEASUREMENTS Comparison between Samsung Advance (headphone with microphone) and class 1 sound level meter - Traffic noise measurement for 100 days

11 OUTDOOR MEASUREMENTS Short term comparison (6 minutes, 1 sample per second)

12 OUTDOOR MEASUREMENTS Long term comparison (1 sample per 5 minutes)

13 OUTDOOR MEASUREMENTS 5 minutes statistics L Aeq,Class 1 L Aeq smartphone db(a) Day Nig Den Minimum -3,3-1,9-1,6 Average -0,5 0,3-0,1 Maximum 1,6 2,5 1,3 Standard deviation 0,8 0,7 0,5

14 FROM SMARTPHONES TO A SELF-BUILT LOW COST NOISE LEVEL METER

15 + RADXA ROCK PRO Android ARM Cortex-A9 quad 1.6Ghz 2GB 800Mhz Wifi Bluetooth USB HDMI STEVAL-MKI116V1 Sound card automatically recognized by the PC as an audio device Powered and connected to PC through USB Digital MEMS microphones 62.6 db signal-to-noise ratio 120 dbspl acoustic overload point 26 dbfs sensitivity using a self-built app for Android

16 Comparison with a Class 1 sound level meter (outdoor measurements for 19 days ) Day (6-22) Day (6-20) Evening (20-22) Night (22-6) DEN Min -0,8-0,7-1,5-1,6-1,4 Average -0,1-0,1-0,1-0,1-0,1 Max 0,5 0,5 0,4 0,8 0,4 Standard deviation 0,3 0,3 0,5 0,7 0,5

17 85 80 Mini-pc Radxa - db(a) min statistic Min -9,8 Average 0,2 Standard deviation Max 9,5 1,0 Count Class 1 Noise Meter - db(a)

18 Graphical overlapping (1 sample per second) Mini pc Radxa Class 1 Noise Meter /06/15 17/06/15 18/06/15 19/06/15 20/06/15 21/06/15 22/06/15 23/06/15 24/06/15 25/06/15 26/06/15 27/06/15 28/06/15 29/06/15 30/06/15 01/07/15 02/07/15 03/07/15 04/07/15 05/07/15 06/07/15 07/07/15 08/07/15 db(a)

19 CONCLUSIONS Good accuracy in measurements with tested smartphones in the range db(a), in some cases up to 110 db(a) Results not valid for all smartphones, due to the presence of automatic gain to adapt microphone response to voice Tests using MEMS microphones and programmable electronic boards give back optimum results Are we ready for the construction of a Class 1 low cost noise level meter?

20 Thank you for your attention