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Step 2Using the NoiseTube mobile application
Getting started
Once you have created an account on the NoiseTube website, found the necessary equipment and installed our software, you can start using the NoiseTube application.
1) You will first have to authenticate yourself with your account details. Once you successfully logged in once, the next time you start it the application will bypass this step.
2) You can now start measuring and contributing to the NoiseTube project.
The user interface
The screenshot in the first figure shows the user interface. Below we discuss the different parts, each of which corresponds to a principal feature of the application.
1) Measuring the loudness of ambient noise
The measurement will start automatically. You can see the current loudness value - measure in dB(A) - at the upper-left. To add meaning to this value it is associated with a colour representing the potential health risk of the current exposure level:
2) Commenting
Tagging adds a layer of meaning to the physical measurements to inform the community and to visualize the nature of the noise on maps afterwards. Like tagging movies on YouTube or webpages on Delicious, you can tag the noise measurements by adding any free words separated by a comma (e.g. the source of the noise or the context, a rating, etc..).
Noise is a complex phenomenon due to the highly subjective way humans perceive it. To study these subjective factors we will add more subjective components to the mobile application to use it as a "(social) annoyance meter" (the 2nd figure shows a preview of what this could look like) and build subjective maps of noise pollution.
3) Geo-localizing measurements
The user can switch to between an automatic (using GPS) or a manual localisation mode by clicking to the localisation icon (see figure 1).
Upon starting the application will activate the automatic mode and try to localize the user using GPS. If it does not succeed (e.g. because of an indoor situation) it will switch to the manual mode, where the user has to enter his location (e.g. a address, the subway station line). It is also possible to select your current location from a list of predefined locations. These locations can be personal "favourites" (e.g.: home or office) or public places (e.g.: streets, subway stations).
More information
About loudness measuring
The loudness meter displays the equivalent continuous sound level (Leq) measured in dB(A) of the sound recorded at a given interval of time. At each cycle the application records the environmental sound (at 22500 Hz, 16bits) during an interval of time, then processes the signal to extract the Leq value. Two intervals are possible: 1) Slow response (1 second, the default mode), this allows to measure the slow sound variation, useful for constant or background noise; 2) Fast response/short Leq (125ms), for time-varying sounds (e.g. short events). The fast response mode is currently still experimental so for now we advice to use the slow response mode.
About sound calibration and information credibility
To calibrate our application to get credible information on a Nokia N95 8GB, we used a sound level meter. We generated a pink noise as source of noise and compared the decibels measured by a sound level meter and those measured by our application on the N95 phone at different levels of loudness (every 5 dB, from 35 dB to 100dB). Figure 3 shows a graph of this the values we registered. We obtained a curve with a precision around +/- 10 dB(A). After using the inverse of this function as a corrector we then obtained good results (precision of +/- 3 db). We plan to do the same calibration with the future iPhone version.
Once you have understood how to use the NoiseTube application, we invite you to test it on the street in your neighbourhood!
Once you have created an account on the NoiseTube website, found the necessary equipment and installed our software, you can start using the NoiseTube application.
1) You will first have to authenticate yourself with your account details. Once you successfully logged in once, the next time you start it the application will bypass this step.
2) You can now start measuring and contributing to the NoiseTube project.
The user interface
The screenshot in the first figure shows the user interface. Below we discuss the different parts, each of which corresponds to a principal feature of the application.
1) Measuring the loudness of ambient noise
The measurement will start automatically. You can see the current loudness value - measure in dB(A) - at the upper-left. To add meaning to this value it is associated with a colour representing the potential health risk of the current exposure level:
- < 60 dB(A): Green (no risk)
- >= 60 and < 70: Yellow (annoying)
- >=70 and <80: Orange (be careful)
- > 80: Red (risky).
2) Commenting
Tagging adds a layer of meaning to the physical measurements to inform the community and to visualize the nature of the noise on maps afterwards. Like tagging movies on YouTube or webpages on Delicious, you can tag the noise measurements by adding any free words separated by a comma (e.g. the source of the noise or the context, a rating, etc..).
Noise is a complex phenomenon due to the highly subjective way humans perceive it. To study these subjective factors we will add more subjective components to the mobile application to use it as a "(social) annoyance meter" (the 2nd figure shows a preview of what this could look like) and build subjective maps of noise pollution.
3) Geo-localizing measurements
The user can switch to between an automatic (using GPS) or a manual localisation mode by clicking to the localisation icon (see figure 1).
Upon starting the application will activate the automatic mode and try to localize the user using GPS. If it does not succeed (e.g. because of an indoor situation) it will switch to the manual mode, where the user has to enter his location (e.g. a address, the subway station line). It is also possible to select your current location from a list of predefined locations. These locations can be personal "favourites" (e.g.: home or office) or public places (e.g.: streets, subway stations).
More information
About loudness measuring
The loudness meter displays the equivalent continuous sound level (Leq) measured in dB(A) of the sound recorded at a given interval of time. At each cycle the application records the environmental sound (at 22500 Hz, 16bits) during an interval of time, then processes the signal to extract the Leq value. Two intervals are possible: 1) Slow response (1 second, the default mode), this allows to measure the slow sound variation, useful for constant or background noise; 2) Fast response/short Leq (125ms), for time-varying sounds (e.g. short events). The fast response mode is currently still experimental so for now we advice to use the slow response mode.
About sound calibration and information credibility
To calibrate our application to get credible information on a Nokia N95 8GB, we used a sound level meter. We generated a pink noise as source of noise and compared the decibels measured by a sound level meter and those measured by our application on the N95 phone at different levels of loudness (every 5 dB, from 35 dB to 100dB). Figure 3 shows a graph of this the values we registered. We obtained a curve with a precision around +/- 10 dB(A). After using the inverse of this function as a corrector we then obtained good results (precision of +/- 3 db). We plan to do the same calibration with the future iPhone version.
Once you have understood how to use the NoiseTube application, we invite you to test it on the street in your neighbourhood!
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