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

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Jacopo Fogola, Stefano Masera, Vincenzo Bevacqua

Environmental Protection Agency - Piedmont Region, Turin, Italy

AS

(2)

OBJECTIVES

1. To study accuracy and precision of environmental noise

measurements through smartphones

(3)

SMARTPHONES AND APPS

SMARTPHONES

1.Samsung @chat 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)

APPS

Noise Meter

(4)

NOISE METER FOR ANDROID

Sampling frequency adjustable: 8000, 11025, 22050, 44100, 48000 Hz

1 dB steps gain, in the range -40 - +40 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: 44100 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

25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 Professional sound level meter - dB(A)

S m ar tp ho ne s - dB (A ) iPhone 5s iPhone 4s HTC 601

Sam s ung Advance Sam s ung @chat

(8)

LABORATORY MEASUREMENTS

Headphones with microphones

25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 Professional sound level meter - dB(A)

S m ar tp ho ne s - dB (A ) iPhone 5s iPhone 4s HTC 601

Sam s ung Advance Sam s ung @chat

(9)

LABORATORY MEASUREMENTS

Class 2 external microphone (MicW i436)

25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 Professional sound level meter - dB(A)

S m ar tp ho ne s - dB (A ) iPhone 5s iPhone 4s HTC 601

(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

(12)

OUTDOOR MEASUREMENTS

(13)

OUTDOOR MEASUREMENTS

5 minutes statistics

LAeq,Class 1 – LAeq 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

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FROM SMARTPHONES

TO A

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+

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

STEVAL-MKI116V1

Android 4.4.2

ARM Cortex-A9 quad core @

1.6Ghz

2GB DDR3 @ 800Mhz

Wifi

Bluetooth

USB

HDMI

RADXA ROCK

PRO

(16)

Comparison with a Class 1 sound level

meter (outdoor measurements for 19

days )

  (6-22)Day (6-20)Day 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

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40 45 50 55 60 65 70 75 80 85 40 45 50 55 60 65 70 75 80 85

Class 1 Noise Meter - dB(A)

M in i-p c R ad xa d B (A ) Min -9,8 Average 0,2 Max 9,5 Standard deviation 1,0 Count 5474

5 min statistic

(18)

45 50 55 60 65 70 75 80 85 16 /0 6/ 15 17 /0 6/ 15 18 /0 6/ 15 19 /0 6/ 15 20 /0 6/ 15 21 /0 6/ 15 22 /0 6/ 15 23 /0 6/ 15 24 /0 6/ 15 25 /0 6/ 15 26 /0 6/ 15 27 /0 6/ 15 28 /0 6/ 15 29 /0 6/ 15 30 /0 6/ 15 01 /0 7/ 15 02 /0 7/ 15 03 /0 7/ 15 04 /0 7/ 15 05 /0 7/ 15 06 /0 7/ 15 07 /0 7/ 15 08 /0 7/ 15 dB (A ) Mini pc Radxa Class 1 Noise Meter

(19)

CONCLUSIONS

Good accuracy

in measurements with tested smartphones in the range

45-80 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

(20)

References

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