Table 1: buzzer buzzing testing results.
60dB 80dB 90dB 105dB
2KHz No No No Yes
3KHz No No No Yes
4KHz No Yes Yes Yes
5KHz No No No Yes
6KHz No No No Yes
10KHz No No No Yes
14KHz No No No Yes
16KHz No Yes Yes Yes
18KHz No No No Yes
20KHz No No No Yes
90dB and 105dB, varying the frequency from 2kHz to
20kHz. The results of our tests are shown in Table 1:
if the buzzer buzzes at the corresponding frequency
and pressure, in the table is reported “Yes”, “No” oth-
erwise. We tested our device in a silent room, without
external sounds, to prevent interferences given from
them.
6 DISCUSSION
This paper started with an introduction to Arduino
and why it is so useful to cope with problems that
are always more relevant nowadays. We choose Ar-
duino for our project for a number of reasons: it is
open-source, it is cheap, it is all-in-one and can be
programmed using C++. Via the combination of all
these features, we got a dedicated microcontroller that
is easily expandable. The sensors and actuators are
relatively cheap, permitting, with a very low budget,
to build one’s own devices. There are a lot of Arduino
libraries available online, that permits rapid develop-
ment of code for any device. Without Arduino and
all its features, a work such as the one described in
this paper would have been more complicated and, in
some cases, it would have not been possible.
For example, a similar work could have been done
using the smartphone, with an App that samples and
analyzes the sounds. We discarded this option, be-
cause, the microphone of the smartphone is not sensi-
ble enough to sample and record the sounds that sur-
round the user, while, with Arduino, we can choose
the most useful microphone, with specific sensibility
and characteristics.
Within the data obtained from the testing, it is
possible to verify that the devices work well, cor-
rectly identifying the potentially dangerous frequen-
cies/pressures. When the noises produced from our
wave generator had a pressure of 60dB, the buzzer on
our device had not been active, because the analyzed
sound was not potentially harmful. When we tested
the device with noises with the pressure set at 80dB,
the buzzer buzzed when the noises reached 4kHz and
16kHz frequencies, correctly advising the user of the
analyzed harmful frequencies. When the noises pro-
duced from our wave generator had a pressure of
90dB, the buzzer buzzed when the noises reached
4kHz and 16kHz frequencies, correctly warning the
user of the potential danger for his ears. When the
noises had a pressure of 105dB, the buzzer was ac-
tive within all the frequencies reached from our wave
generator, because we consider dangerous noises at so
high pressure. The buzzer buzzing volume is propor-
tional to the pressure of the analyzed noises.
A problem that is possible to identify in our sys-
tem is the microphone sensibility, that, in some cases,
cannot be enough to sample very high sound pres-
sures: the microphone we used for testing is a con-
sumer one, that can be bought from everybody to
build own devices, and not a professional one; so, the
precision is not so high for professional use; it may
lead to a loss of precision during measurements.
Another problem that is possible to identify is the
”backtracking effect”: using a buzzer to alert the user
when dangerous noises are revealed, the sound of the
buzzer may act as an input for our microphone, loop-
ing through the system. To prevent this, our buzzer
produces sounds with a frequency of 10kHz and with
a volume between 30dB and 50dB (reprogrammable);
being this kind of sound unharmful, our algorithm
simply discards it and does not act as a recursive in-
put for our device. If, for example, our buzzer had a
frequency of 4kHz and a volume of 70dB, it will have
acted as a dangerous sound source, producing sounds
considered harmful by our device, and causing our
buzzer to increase the volume, causing detection of
more dangerous sounds, and so on.
Another problem that is possible to identify is that,
if our device is used in a place with other people in the
near surroundings, the device can eventually be dis-
turbing for them, if the buzzer buzzes continuously.
A way to avoid this, without losing the feature of be-
ing suitable for blind people, is simply to decrease the
volume of the buzzer: being the device volume repro-
grammable, it is possible to set to a very low buzzing
volume range, for example, 5dB to 10dB, resulting no
more disturbing for people in the surroundings.
From the testing results, we can ensure that our
device works correctly with respect to the workflow,
properly identifying the potentially dangerous fre-
quencies/pressures.
An Arduino-based Device to Detect Dangerous Audio Noises
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