Suspended audio device with bass boost performance
Disclosed is a suspended audio device with bass enhancement performance, including a low-pass filter, a high-pass filter, an energy controller and a harmonic generator. The low-pass filter is configured to extract a low-frequency signal in an original input signal, and input the low-frequency signal as a fundamental wave of the harmonic generator; the high-pass filter is configured to extract a mid-high frequency signal in the original input signal; the harmonic generator is configured to process the low-frequency signal extracted by the low-pass filter through the NLD algorithm, and generate at least one enhanced harmonic signal in the low-frequency signal; the energy controller is configured to control an overall gain of the at least one enhanced harmonic signal generated by the harmonic generator.
1 . An audio device with bass enhancement performance, comprising:
a low-pass filter configured to extract a low-frequency signal in an original input signal and input the low-frequency signal as a fundamental wave of a harmonic generator;
a high-pass filter configured to extract a mid-high frequency signal in the original input signal;
the harmonic generator configured to process the low-frequency signal extracted by the low-pass filter through a Non-Linear Device (NLD) algorithm, and generate at least one enhanced harmonic signal in the low-frequency signal; and
an energy controller configured to control an overall gain of the at least one enhanced harmonic signal generated by the harmonic generator;
wherein the NLD algorithm adopted in the harmonic generator comprises:
step S 1 , defining a power series and a polynomial, using a sum of an infinite power series to represent a function y:
y
=
f
(
x
)
=
∑
n
=
0
∞
h
n
x
n
,
(
2.1
)
where h n represents a coefficient of the nth power series, and x and y represent an input and output, respectively,
y is expressed approximately by using finite items and finite power series ŷ,
y
^
=
f
^
(
x
)
=
∑
n
=
0
Q
h
^
n
x
n
,
(
2.2
)
and setting
lim
Q
→
∞
y
^
=
y
,
wherein Q represents the highest order;
step S 2 , harmonic analysis:
defining a single-tone signal with an initial phase set to 0:
x ( t )= A cos( wt ), (2.3),
where A represents amplitude, w represents angular velocity in radians per second, and t represents time in seconds,
substituting formula (2.3) into formula (2.2) to get:
g
ˆ
(
t
)
=
c
^
0
2
+
∑
k
=
1
P
c
^
k
cos
(
kwt
)
,
(
2.4
)
where P is an upper bound of a harmonic order, ĉ k is the coefficient of an finite Fourier series and is also the amplitude of the kth harmonic, and
c
o
^
2
is a direct current component,
deriving the relationship between ĉ k and ĥ n from formulas (2.2) and (2.4);
c
ˆ
k
=
𝒥
^
a
(
A
,
h
ˆ
n
)
=
1
2
k
-
1
∑
j
=
0
L
j
=
[
(
Q
-
k
)
/
2
]
A
k
+
2
j
h
ˆ
n
2
2
j
(
k
+
2
j
j
)
,
(
2.5
)
where
n
=
k
+
2
j
,
and
k
=
0
,
1
,
2
,
…
,
(
L
k
=
Q
)
;
h
ˆ
n
=
𝒥
^
s
(
A
,
c
^
k
)
=
2
n
-
1
A
n
-
1
∑
j
=
0
L
j
=
[
(
P
-
n
)
/
2
]
(
-
1
)
j
n
+
2
j
n
+
j
(
n
+
j
j
)
c
^
k
,
(
2.6
)
where k=n+2j, and n=0,1,2 . . . , (L n =P),
according to formula (2.5), for the coefficient ĥ n of the existing power series, analyzing the amplitudes of each harmonic component contained thereof, and according to formula (2.6), constructing the amplitude coefficients ĉ k of each harmonic component to calculate the corresponding coefficients ĥ n of the power series,
and substituting ĥ n into the formula (2.1) after obtaining ĥ n and making calculations to obtain the harmonic; and
step S 3 , selecting a series of functions f(x) and calculating ĥ n and ĉ k finding suitable ĥ n and ĉ k , modulating an audio data stream by the f(x), testing the modulated audio stream, and selecting the most appropriate modulation function f(x) according to the test results.
2 . The audio device with bass enhancement performance according to claim 1 , wherein the harmonic generator is configured to generate two-path harmonic signals.
3 . The audio device with bass enhancement performance according to claim 2 , further comprising a delayer configured to perform delay processing before adding the two-path harmonic signals to ensure that the two-path harmonic signals remain consistent before adding.
4 . The audio device with bass enhancement performance according to claim 2 , wherein the energy controller comprises a gain controller G1 and a gain controller G2, and the gain controller G1 and the gain controller G2 are respectively configured to control the gains of the two-path harmonic signals.