Hearing protection method capable of blocking external high-sound-pressure-level energy
The present disclosure provides a hearing protection method capable of blocking external high-sound-pressure-level energy, including: a second sound pressure energy threshold being greater than a first sound pressure energy threshold; when an external sound energy value is greater than the first sound pressure energy threshold and is less than the second sound pressure energy threshold, enabling a preset active noise cancellation function; and when the external sound energy value is greater than the second sound pressure energy threshold, disabling the preset active noise cancellation function, and blocking high-sound-pressure-level energy by means of passive noise cancellation. The present disclosure can block the external high-sound-pressure-level energy.
1. A hearing protection method capable of blocking external high-sound-pressure-level energy, comprising the following steps:
Step S1: presetting a first sound pressure energy threshold and a second sound pressure energy threshold, the second sound pressure energy threshold being greater than the first sound pressure energy threshold;
Step S2: obtaining an external sound energy value;
Step S3: comparing the external sound energy value with the first sound pressure energy threshold and the second sound pressure energy threshold, when the external sound energy value is greater than the first sound pressure energy threshold and is less than the second sound pressure energy threshold, performing Step S4, and when the external sound energy value is greater than the second sound pressure energy threshold, performing Step S5;
Step S4: enabling a preset active noise cancellation function to reduce high-sound-pressure-level energy; and
Step S5: disabling the preset active noise cancellation function, and blocking the high-sound-pressure-level energy by means of passive noise cancellation.
2. The hearing protection method capable of blocking external high-sound-pressure-level energy according to claim 1 , wherein in the Step S1, a sound pressure energy level of a feed forward microphone (FF MIC), equivalent to a sound pressure level (SPL) of 80 dBA at an eardrum of a user, is taken as the first sound pressure energy threshold.
3. The hearing protection method capable of blocking external high-sound-pressure-level energy according to claim 1 , wherein in the Step S1, a high sound pressure energy level, about to be saturated, of an FF MIC obtained by a laboratory test is taken as the second sound pressure energy threshold.
4. The hearing protection method capable of blocking external high-sound-pressure-level energy according to claim 1 , wherein in the Step S2, the external sound energy value is obtained by an FF MIC or a Talk MIC.
5. The hearing protection method capable of blocking external high-sound-pressure-level energy according to claim 4 , wherein in the Step S2, the process of obtaining the external sound energy value comprises: converting the change of an external sound signal acquired in real time by the FF MIC or the Talk MIC into an audio data stream, and calculating the audio data stream by means of an A-weighted digital system to obtain the current external sound energy value,
wherein a transfer function of the A-weighted digital system is as follows:
A
(
S
)
=
1
0
-
A
1
0
0
0
2
0
[
Ω
4
2
S
2
(
S
2
+
Ω
1
2
)
2
(
S
2
+
Ω
2
2
)
(
S
2
+
Ω
3
2
)
(
S
2
+
Ω
4
2
)
2
]
,
wherein
Ω
1
=
2
π
f
1
,
Ω
2
=
2
π
f
2
,
Ω
3
=
2
π
f
3
,
Ω
4
=
2
π
f
4
,
A
1
0
0
0
=
1.9997
,
f
1
=
20.6
Hz
,
f
2
=
107.7
Hz
,
f
3
=
737.9
Hz
,
f
4
=
12194
Hz
;
converting the transfer function of the A-weighted digital system into a digital filter by means of MATLAB software, and obtaining a filter coefficient h(n); and
if the input audio data stream is set as x(n), then outputting y(n) after processing by the A-weighted digital system, and calculating a sound pressure level of y(n) data to obtain a dBA value of a current audio,
wherein a formula for calculating the sound pressure level is as follows:
SPL
=
20
×
log
10
p
e
p
ref
,
wherein
p
e
=
1
N
∑
n
=
1
N
x
2
(
n
)
,
p
ref
=
2
×
10
-
5
.
6. The hearing protection method capable of blocking external high-sound-pressure-level energy according to claim 5 , wherein the transfer function of the A-weighted digital system is converted into the digital filter by means of bilinear transformation.
7. The hearing protection method capable of blocking external high-sound-pressure-level energy according to claim 1 , wherein a virtual switch is correspondingly provided in the hearing protection method and is arranged in a preset application (App), the Step S1 to the Step S5 are performed when the virtual switch is turned on, and the Step S1 to the Step S5 are not performed when the virtual switch is turned off.