CN113192525A

CN113192525A - Audio playing device and method with anti-noise mechanism

Info

Publication number: CN113192525A
Application number: CN202010036957.7A
Authority: CN
Inventors: 何维鸿
Original assignee: Realtek Semiconductor Corp
Current assignee: Realtek Semiconductor Corp
Priority date: 2020-01-14
Filing date: 2020-01-14
Publication date: 2021-07-30

Abstract

The invention comprises an audio playing device with an anti-noise mechanism and a method thereof. The device comprises: a radio circuit, an adjusting parameter generating circuit, a frequency warping filter circuit and an audio playing circuit. The radio circuit receives radio audio. The adjusting parameter generating circuit generates a plurality of adjusting parameters at least according to the received audio frequency. The frequency warping filter circuit includes: a first-order all-pass filter unit, a multiplication unit and a superposition circuit connected in series. The first-order all-pass filtering unit sequentially filters according to the received audio frequency to generate a plurality of filtering results. The multiplication units respectively multiply one of the received audio and the filtering result with one of the adjusting parameters to generate one of a plurality of adjusting filtering results. The superposition circuit superposes and adjusts the filtering result to be used as the anti-noise audio. The audio playing circuit plays the actual audio and the anti-noise audio simultaneously.

Description

Audio playing device and method with anti-noise mechanism

Technical Field

The present invention relates to audio playing technologies, and in particular, to an audio playing device and method with an anti-noise mechanism.

Background

In order to make a user have a better listening effect when listening to music, many earphones are provided with an anti-noise mechanism to avoid the ambient noise interfering with the listening. In recent years, earphones are often equipped with an active anti-noise mechanism, in which a microphone receives noise and filters the noise according to a filter coefficient to generate anti-noise audio in an inverted phase to cancel the effect of the noise.

However, in general earphone applications, if an adaptive filtering mechanism is required, the order of the filter must be more than several hundreds to have sufficient frequency resolution due to the high sampling rate required by the filter. However, if a lower sampling rate is to be used, the additional down-conversion and up-conversion processes both add delay. When the delay is too large, the noise cancellation mechanism cannot cancel the noise in real time.

Disclosure of Invention

In view of the foregoing, it is an object of the present invention to provide an audio playback apparatus and method with an anti-noise mechanism to improve the prior art.

An objective of the present invention is to provide an audio playing device and method with an anti-noise mechanism, which compress the received audio to low frequency through the filtering of the frequency warping filter circuit, so that the frequency warping filter circuit can operate at a high sampling rate without requiring excessive orders.

The invention includes an audio playing device with an anti-noise mechanism, comprising: the device comprises a radio receiving circuit, an adjusting parameter generating circuit, a frequency warping (filtering) circuit and an audio playing circuit. The sound receiving circuit is configured to receive sound receiving audio. The adjusting parameter generating circuit is configured to generate a plurality of adjusting parameters at least according to the received audio. The frequency warping filter circuit includes: a plurality of first-order all-pass filter units connected in series, a plurality of multiplication units and a superposition circuit. The first-order all-pass filtering unit is configured to sequentially filter according to the received audio to generate a plurality of filtering results. The multiplication unit is configured to multiply one of the received audio and the filtering result with one of the adjusting parameters, respectively, to generate one of a plurality of adjusting filtering results. The superimposing circuit is configured to superimpose the adjusted filtering result as the anti-noise audio. The audio playback circuit is configured to play the actual audio and the anti-noise audio simultaneously.

The present invention further provides an audio playing method applied to an audio playing device with an anti-noise mechanism, comprising: enabling the radio circuit to receive radio audio; the adjusting parameter generating circuit generates a plurality of adjusting parameters at least according to the received audio frequency; the frequency warping filter circuit comprises a plurality of first-order all-pass filter units connected in series and sequentially filtering according to the received audio to generate a plurality of filtering results; the frequency warping filter circuit comprises a plurality of multiplication units which respectively multiply one of the received audio and the filtering result with one of the adjusting parameters to generate one of a plurality of adjusting filtering results; a superimposing circuit included in the frequency warping filter circuit superimposes the adjustment filter result as an anti-noise audio; and causing the audio playback circuit to play the actual audio and the anti-noise audio simultaneously.

The features, practice and effect of the present invention will be described in detail with reference to the drawings.

Drawings

FIG. 1 is a block diagram of an audio playback device with an anti-noise mechanism according to an embodiment of the present invention;

FIG. 2 is a block diagram showing a frequency warping filter circuit in more detail, according to an embodiment of the present invention;

FIG. 3 is a block diagram showing in greater detail the frequency warp delay circuit in one embodiment of the present invention;

FIG. 4 is a block diagram of an audio playback device with an anti-noise mechanism according to an embodiment of the present invention;

FIG. 5 is a block diagram of an audio playback device with an anti-noise mechanism according to an embodiment of the present invention; and

FIG. 6 is a flowchart illustrating an audio playing method with an anti-noise mechanism according to an embodiment of the present invention.

Detailed Description

An objective of the present invention is to provide an audio playing device and method with an anti-noise mechanism, which can compress the received audio to a low frequency through the filtering of the frequency warping filter circuit, so that the frequency warping filter circuit can operate at a high sampling rate without requiring excessive orders.

Please refer to fig. 1. Fig. 1 is a block diagram of an audio playback device 100 with an anti-noise mechanism according to an embodiment of the present invention. The audio playing device 100 includes: the

audio receiving circuit

110A, 110B, the adjusting parameter generating circuit 120, the frequency warping (frequency warping) filter circuit 130, and the audio playing circuit 140.

In one embodiment, the radio receiving circuit 110A is an internal radio receiving circuit, and the radio receiving circuit 110B is an external radio receiving circuit. In one embodiment, the audio playback device 100 is, for example, but not limited to, a headphone, and may include a housing (not shown). The circuits for audio processing and playing, such as the adjustment parameter generating circuit 120, the frequency warping filter circuit 130 and the audio playing circuit 140, are disposed inside the housing. The internal radio receiving circuit 110A is disposed inside the housing, and the external radio receiving circuit 110B is disposed outside the housing.

The

radio circuits

110A, 110B receive radio audios AIA n and AOA n, respectively. In more detail, the internal sound receiving circuit 110A receives the internal sound receiving audio AIA [ n ] inside the housing by being disposed inside the housing. In contrast, the external sound receiving circuit 110B is disposed outside the housing, and receives external sound receiving audio AOA [ n ] outside the housing. The parameter n varies with value and corresponds to different points in time.

In one embodiment, the audio playback device 100 may further include an analog-to-digital conversion circuit 150A (labeled as a/D in fig. 1) and a subtraction circuit 160. The analog-to-digital conversion circuit 150A receives the internal radio reception audio AIA [ n ] in analog form from the internal radio reception circuit 110A, and performs analog-to-digital conversion to generate the internal radio reception audio AID [ n ] in digital form. Since the actual audio XS [ n ] (including music or human voice, for example) played by the audio playing circuit 140 inside the housing is also received by the internal sound receiving circuit 110A, the subtracting circuit 160 subtracts the portion of the internal sound receiving audio AID [ n ] corresponding to the actual audio XS [ n ] to generate the actual internal sound receiving audio AIS [ n ].

In one embodiment, to simulate the response of the path played from the audio playing circuit 140 to the internal sound receiving circuit 110A, the audio playing apparatus 100 may further include a response simulation circuit 170A for filtering the actual audio XS [ n ] corresponding to the path response to generate simulated actual audio XSS [ n ]. The subtraction circuit 160 essentially subtracts the internal radio audio AID [ n ] and the emulated actual audio XSS [ n ] to produce the actual internal radio audio AIS [ n ].

In one embodiment, the audio playback device 100 may further include an analog-to-digital conversion circuit 150B (labeled as a/D in fig. 1) for receiving the external radio audio aoan [ n ] in analog form from the external radio circuit 110B and performing analog-to-digital conversion to generate the external radio audio AOD [ n ] in digital form. Since the external sound receiving circuit 110B does not receive the actual audio XS [ n ] played by the audio playing circuit 140 inside the housing, no subtraction is required for the external sound receiving audio AOD [ n ].

Please refer to fig. 2. Fig. 2 is a more detailed block diagram of the frequency warping filter circuit 130 according to an embodiment of the present invention. The frequency warping filter circuit 130 includes: multiple series-connected first-order all-pass filter units AF₁～AF_kA plurality of multiplication units MU₀～MU_kAnd a superimposing circuit 200.

First order all-pass filter unit AF₁～AF_kAccording to external radio audio AOD [ n ]]Sequentially filtering to generate a filtering result FR₀[n]～FR_k[n]. The different values k represent the first order all-pass filter units AF of the frequency warping filter circuit 130₁～AF_kThe order of (a).

In one embodiment, each first-order all-pass filter unit AF₁～AF_kThe response of (c) can be expressed as a (z) in the z-frequency domain, and a (z) ═ a + z^-1)/(1-a×z^-1) Wherein a is a number between 0 and 1. In one embodiment, the larger the value of a, the lower the delay at high frequencies and the higher the delay at low frequencies.

Multiplication unit MU₀～MU_kRespectively receive external audio AOD [ n ]]And a filtering result FR₁[n]～FR_k[n]One of them and the adjustment parameter W₀[n]～W_k[n]One of which is multiplied to produce the adjusted filtered result MFR₀～MFR_kOne of them.

In more detail, the multiplication unit MU₀Make the external audio AOD and the adjustment parameter W₀[n]The multiplication results in an adjusted filtering result MFR₀. Multiplication unit MU₁Let the filtering result FR₁And adjusting the parameter W₁[n]The multiplication results in an adjusted filtering result MFR₁. Multiplication unit MU₂Let the filtering result FR₂And adjusting the parameter W₂[n]The multiplication results in an adjusted filtering result MFR₂. And so on until the multiplication unit MU_kMake the filter junctionFruit FR_kAnd adjusting the parameter W_k[n]The multiplication results in an adjusted filtering result MFR_k。

Superimposing circuit 200 superimposes and adjusts filter result MFR₀～MFR_kFor anti-noise audio FAS [ n ]]. In one embodiment, the overlay circuit 200 includes an overlay unit ADD₁～ADD_kIn which the ADD unit ADD₁Will adjust the filter result MFR₀And adjusting the filtered result MFR₁And (6) performing superposition. Add-on unit ADD₂ADD the superposition unit ADD₁The result of the superposition and the result of the adjustment filtering MFR₂And (6) performing superposition. And so on until the superposition unit ADD_kADD the superposition unit ADD_k-1The result of the superposition and the result of the adjustment filtering MFR_kSuperimposing to output anti-noise audio FAS [ n ]]. Anti-noise audio FAS [ n ]]The response of (c) may be expressed as:

due to the adjustment of the parameter W₀[n]～W_k[n]The frequency warping filter circuit 130 is an adaptive filter circuit because it varies with time.

The adjustment parameter generating circuit 120 generates AID [ n ] according to the received audio, such as the internal received audio]And an external radio audio AOD [ n ]]Generating an adjustment parameter W₀[n]～W_k[n]。

In one embodiment, the tuning parameter generating circuit 120 actually receives the actual internal received audio AIS [ n ] for the internal received audio AID [ n ], which is generated by subtracting the simulated actual audio XSS [ n ] simulated by the response simulation circuit 170A from the internal received audio AID [ n ].

In one embodiment, the tuning parameter generation circuit 120 receives the external radio audio AOD [ n ] through the process of response simulation and frequency warping for the external radio audio AOD [ n ].

In more detail, the audio playback device 100 further includes a response simulation circuit 170B simulating a response of a path played back from the audio playback circuit 140 to the internal sound receiving circuit 110A, and filtering the external sound receiving audio AOD [ n ] according to the path response to generate a filtered sound receiving audio XOS [ n ].

Furthermore, the audio playback apparatus 100 further comprises a frequency warping delay circuit 180 for generating a plurality of delay results DR by performing a filtering delay on the filtered received audio XOS₀[n]～DR_k[n]。

Please refer to fig. 3. Fig. 3 is a more detailed block diagram of the frequency warp delay circuit 180 in accordance with one embodiment of the present invention. The frequency warping delay circuit 180 includes: cascaded first-order all-pass filter delay units AFD₁～AFD_kAccording to the filtered radio frequency XOS [ n ]]Sequentially filtering and delaying to generate a delayed result DR₀[n]～DR_k[n]. Wherein the result DR is delayed₀[n]Equivalent to the filtered radio reception audio XOS [ n ]]The result after 0 delays. Delayed result DR₁[n]For filtered radio reception audio XOS [ n ]]After passing through 1 first-order all-pass filtering delay unit AFD₁As a result of the delay of (c). Delayed result DR₂[n]The filtered radio reception audio XOS passes through 2 first-order all-pass filtering delay units AFD₁、AFD₂As a result of the delay of (c). By analogy, the result DR is delayed_k[n]For filtered radio reception audio XOS [ n ]]Through k first-order all-pass filtering delay units AFD₁～AFD_kAs a result of the delay of (c).

Therefore, the tuning parameter generating circuit 120 actually receives the external audio AOD [ n ]]Delay result DR generated after response simulation and frequency warping processing₀[n]～DR_k[n]。

In one embodiment, the tuning parameter generating circuit 120 may generate the tuning parameter W according to, for example, but not limited to, a Least Mean Square (LMS) algorithm₀[n]～W_k[n]. To adjust the parameter W₀[n]For example, it can be calculated by:

W₀[n]＝W₀[n-1]-μ×AIS[n]×DR₀[n]

wherein, W₀[n]For the adjustment parameter at the corresponding time point n, W₀[n-1]AIS [ n ] is a previous adjustment parameter corresponding to a previous time point n-1]For actual internal reception audio corresponding to time point n，DR₀[n]As a result of the delay corresponding to time point n. And μ is an adjustable parameter, the size of which determines the speed of convergence.

All tuning parameters W_K[n]All can pass through the corresponding previous adjusting parameter W_K[n-1]And delayed result DR_K[n]With the parameter mu and the actual internal reception audio AIS [ n ]]And performing calculation generation. Wherein K is 0 to K.

In other embodiments, the tuning parameter generating circuit 120 may generate the tuning parameter W according to a Normalized Least Mean Square (NLMS) algorithm or other suitable algorithm₀[n]～W_k[n]The present invention is not limited to the above embodiments.

According to the above, the adjustment parameter generating circuit 120 is actually based on the delay result DR₀[n]～DR_k[n]Actual internal reception audio AIS [ n ]]And a previous tuning parameter W₀[n-1]～W_k[n-1]Generating an adjustment parameter W₀[n]～W_k[n]. Wherein the parameter W is adjusted previously₀[n-1]～W_k[n-1]The feedback signal may be calculated by the frequency warping filter circuit 130 as shown in fig. 1, or may be stored and retrieved when needed by a storage circuit (not shown) additionally disposed in the audio playback apparatus 100.

Therefore, the frequency warping filter circuit 130 generates the tuning parameter W according to the tuning parameter generating circuit 120₀[n]～W_k[n]After filtering the external radio audio AOD, outputting anti-noise audio FAS [ n ]]. The audio playback circuit 140 plays the actual audio XS [ n ] simultaneously]And anti-noise audio FAS [ n ]]。

In one embodiment, the audio playback device 100 further includes a synthesizing circuit 190 and a digital-to-analog converting circuit 195 (labeled as D/a in fig. 1). The synthesizing circuit 190 superimposes the actual audio XS [ n ] and the anti-noise audio FAS [ n ], and the digital-to-analog conversion circuit 195 performs digital-to-analog conversion on the superimposed result and transmits the result to the audio playing circuit 140 for playing.

In some techniques, the processing of the external received audio by the filter circuit often requires a relatively high number of filter unit orders to achieve sufficient frequency resolution. Even with lower sampling rates, this is of limited benefit for order reduction, and requires additional up-conversion and down-conversion of the signal, resulting in undesirable delays.

Therefore, the audio playback device 100 of the present invention can compress the external audio AOD [ n ] to low frequency by the filtering of the frequency warping filter circuit 130, and concentrate the compressed audio in the range of 20 Hz to 2 kHz, which is easily perceived by human ears, for example, but not limited thereto. Thus, the frequency warped filter circuit 130 may operate at a high sampling rate (e.g., without limitation, 768 kilohertz) without requiring an excessive number of orders (e.g., without limitation, 30 orders or less).

In the audio playback device 100, the frequency warping filter circuit 130 filters the externally received audio AOD [ n ] to generate anti-noise audio FAS [ n ], which is thus a feed-forward mechanism. In other embodiments, the audio playing device may also generate the anti-noise audio only by using the feedback mechanism through the internal radio audio AID [ n ].

Please refer to fig. 4. Fig. 4 is a block diagram of an audio playback device 400 with an anti-noise mechanism according to an embodiment of the present invention. The audio playing device 400 includes: the audio receiving circuit 110A, the adjusting parameter generating circuit 420, the frequency warping filter circuit 430 and the audio playing circuit 140.

In the embodiment, the audio playing apparatus 400 only includes the internal audio receiving circuit 110A to receive the internal audio receiving audio AIA [ n ].

The audio playing apparatus 400 may further include an analog-to-digital conversion circuit 150A (labeled as a/D in fig. 4) and a subtraction circuit 160, which respectively receive the analog form of the internal picked-up audio AIA [ n ] for analog-to-digital conversion to generate the digital form of the internal picked-up audio AID [ n ] and subtract a portion of the internal picked-up audio AID [ n ] corresponding to the actual audio XS [ n ] to generate the actual internal picked-up audio AIS [ n ].

Moreover, the audio playback apparatus 400 may further include a response simulation circuit 170A for performing a corresponding path response filtering on the actual audio XS [ n ] to generate a simulated actual audio XSs [ n ]. The subtraction circuit 160 essentially subtracts the internal received audio AID [ n ] from the emulated actual audio XSS [ n ] to produce the actual internal received audio AIS [ n ].

The structure of the frequency warping filter circuit 430 is the same as the frequency warping filter circuit 130 shown in fig. 2, and therefore, the description thereof is omitted. The difference with the frequency warping filter circuit 130 shown in FIG. 2 is that the frequency warping filter circuit 430 receives the actual internal sound pickup audio AIS [ n ] minus the feed sound pickup audio FIS [ n ] generated by the previously generated anti-noise audio BAS [ n-1] and performs frequency warping filtering to output the feedback anti-noise audio BAS [ n ]. In an embodiment, the audio playback device 400 may further include a response simulation circuit 470A and a subtraction circuit 460. The response simulation circuit 470A is configured to receive the anti-noise audio BAS [ n-1] from the frequency warping filter circuit 430, perform path response filtering to generate a simulated anti-noise audio BSS [ n ], and generate a feed-in audio FIS [ n ] by subtracting the simulated anti-noise audio BSS [ n ] from the actual internal radio audio AIS [ n ] by the subtraction circuit 460, and transmit the feed-in audio FIS [ n ] to the frequency warping filter circuit 430 for frequency warping filtering.

Further, the tuning parameter generating circuit 420 generates the tuning parameter according to the received audio, such as the actual internal received audio AIS [ n ]]Generating an adjustment parameter W₀[n]～W_k[n]。

In one embodiment, the audio playback device 400 may further include a response simulation circuit 470B and a frequency warping delay circuit 480 for respectively responding to the actual internal received audio AIS [ n ]]Performing response simulation filtering and frequency warping delay to generate delay result DR₀[n]～DR_k[n]. The adjusting parameter generating circuit 420 can generate the DR according to the delay result₀[n]～DR_k[n]Actual internal reception audio AIS [ n ]]And a previous tuning parameter W₀[n-1]～W_k[n-1]Generating an adjustment parameter W₀[n]～W_k[n]。

Therefore, the frequency warping filter circuit 430 generates the tuning parameter W according to the tuning parameter generating circuit 420₀[n]～W_k[n]After filtering the external radio audio AOD, the output anti-noise audio BAS [ n [ ]]. The audio playback circuit 140 plays the actual audio XS [ n ] simultaneously]And anti-noise audio BAS [ n ]]。

In one embodiment, the audio playback device 400 further comprises a synthesizer circuit 190 and a DAC circuit 195 for respectively superimposing the actual audio XS [ n ] and the anti-noise audio BAS [ n ] and performing digital-to-analog conversion on the superimposed audio and the anti-noise audio BAS [ n ] and transmitting the superimposed audio and the anti-noise audio BAS [ n ] to the audio playback circuit 140 for playback.

Please refer to fig. 5. Fig. 5 is a block diagram of an audio playback device 500 with an anti-noise mechanism according to an embodiment of the present invention. Similar to the audio playback device 100 of fig. 1, the audio playback device 500 includes: the audio receiving circuit 110A, the audio receiving circuit 110B, the adjusting parameter generating circuit 120, the frequency warping filter circuit 130 and the audio playing circuit 140. These components are the same as the corresponding components of FIG. 1, and the filtering mechanism that performs the feedforward produces the anti-noise audio FAS [ n ].

In the present embodiment, the audio playback device 500 further includes a feedback filter circuit 510, and the feedback filter circuit 510 may have an adjustment parameter generating circuit 420, a frequency warping filter circuit 430, a subtracting circuit 460, a response simulating circuit 470A, a response simulating circuit 470B and a frequency warping delay circuit 480 as included in the audio playback device 400 of fig. 4, and a filter mechanism for performing feedback generates the anti-noise audio BAS [ n ].

In one embodiment, the audio playback device 500 further includes a synthesizer circuit 190 and a digital-to-analog converter circuit 195, which superimpose the actual audio XS [ n ], the anti-noise audio FAS [ n ] and the anti-noise audio BAS [ n ], respectively, and then perform digital-to-analog conversion on the superimposed result and transmit the result to the audio playback circuit 140 for playback.

Therefore, the audio playback device 500 can generate anti-noise audio by using both feedforward and feedback mechanisms.

It should be noted that the above embodiments are exemplified by adaptive filtering of both feedforward and feedback mechanisms. In other embodiments, the feedforward mechanism of adaptive filtering and the feedback mechanism of fixed coefficient filtering, or the feedforward mechanism of fixed coefficient filtering and the feedback mechanism of adaptive filtering, may be selectively adopted.

In one embodiment, for better performance, the audio playback device 100 may optionally set a fixed coefficient boost (boost) filter after the analog-to-digital conversion circuit 150B to perform boost filtering on the externally received audio AOD [ n ] to enhance the performance of a specific frequency band, such as but not limited to increasing the gain of low frequencies, for the subsequent processing of the frequency warping filter circuit 130 and the response simulation circuit 170B.

In another embodiment, for better performance, the audio playback device 100 may selectively set a band pass filter 710 between the analog-to-digital conversion circuit 150B and the response simulation circuit 170B to filter the analog-to-digital converted external audio AOD [ n ] to enhance the specific frequency band, so as to converge the convergence effect to a specific frequency band, such as but not limited to 200 hz to 1 khz, for the subsequent processing of the response simulation circuit 170B.

Both of the above-described filtering mechanisms can be applied to the path of the feedback mechanism.

Please refer to fig. 6. Fig. 6 is a flowchart of an audio playing method 600 with an anti-noise mechanism according to an embodiment of the present invention.

In addition to the aforementioned devices, the present invention further discloses an audio playing method 600 with an anti-noise mechanism, which is applied to, for example, but not limited to, the audio playing device 100 of fig. 1. One embodiment of an audio playback method 600 is shown in FIG. 6, comprising the following steps:

s610: the radio circuit receives radio audio.

In one embodiment, the sound receiving circuit may include an internal sound receiving circuit 110A and/or an external sound receiving circuit 110B for receiving the received audio including an internal received audio AIA and/or an external received audio AOD.

S620: the adjusting parameter generating circuit 120 generates the adjusting parameter W at least according to the received audio₀[n]～W_k[n]。

S630: the frequency warping filter circuit 130 includes an all-pass filter unit AF₁～AF_kSequentially filtering according to the external audio AOD to generate a filtering result FR₁[n]～FR_k[n]。

S640: the frequency warping filter circuit 130 includes a multiplication unit MU₀～MU_kRespectively receiving the external audio AOD and the filtering result FR₁[n]～FR_k[n]One of them and the adjustment parameter W₀[n]～W_k[n]One of which is multiplied to produce a modified filterResults MFR₀～MFR_kOne of them.

S650: the frequency warping filter circuit 130 includes a superimposing circuit 200 for superimposing the adjustment filter result MFR₀～MFR_kAs anti-noise audio FAS [ n ]]。

S660: the audio playback circuit 140 is caused to play the actual audio XS simultaneously with the anti-noise audio FAS n.

The above flow is described in terms of a feed forward mechanism. In one embodiment, the above process can also be applied to a feedback mechanism.

It should be noted that the above-mentioned embodiments are only examples. In other embodiments, one of ordinary skill in the art can make modifications without departing from the spirit of the present invention.

In summary, the audio playing apparatus and method of the present invention can compress the received audio to low frequency through the filtering of the frequency warping filter circuit, so that the frequency warping filter circuit can operate at a high sampling rate without excessive orders.

Although the embodiments of the present invention have been described above, these embodiments are not intended to limit the present invention, and those skilled in the art can apply variations to the technical features of the present invention according to the explicit or implicit contents of the present invention, and all such variations may fall within the scope of the patent protection sought by the present invention.

[ notation ] to show

100. 400, 500 audio playing device

110A, 110B radio circuit

120. 420 adjusting parameter generating circuit

130. 430 frequency warping filter circuit

140 audio playing circuit

150A, 150B analog-to-digital conversion circuit

160. 460 subtraction circuit

170A, 170B, 470A, 470B response simulation circuit

180. 480 frequency warping delay circuit

190 synthesizer circuit

195 digital-to-analog conversion circuit

200 superposition circuit

510 feedback filter circuit

600 audio playing method

S610 to S660

ADD₁～ADD_kSuperimposing unit

AF₁～AF_kFirst-order all-pass filtering unit

AFD₁～AFD_kFirst-order all-pass filtering delay unit

AIA [ n ], AID [ n ] internal radio reception audio

AIS [ n ] actual internal reception audio

AOAN, AODn external sound reception audio

BAS [ n ], BAS [ n-1], FAS [ n ] anti-noise audio

BSS [ n ] simulation anti-noise audio

DR₀[n]～DR_k[n]Delay the result

FIS [ n ] feed-in radio audio

FR₁[n]～FR_k[n]Result of filtering

MFR₀～MFR_kAdjusting the filtering result

MU₁～MU_kMultiplication unit

W₀[n]～W_k[n]Adjusting parameters

W₀[n-1]～W_k[n-1]Previous adjustment parameters

XOS [ n ] filtered radio reception audio

XS [ n ] actual audio

XSS [ n ] emulates the actual audio.

Claims

1. An audio playback device with an anti-noise mechanism, comprising:

a radio circuit configured to receive a radio audio;

an adjustment parameter generating circuit configured to generate a plurality of adjustment parameters at least according to the received audio;

a frequency warped filter circuit, comprising:

a plurality of first-order all-pass filtering units connected in series and configured to sequentially filter according to the received audio to generate a plurality of filtering results;

a plurality of multiplication units configured to multiply the received audio frequency and one of the plurality of filtering results with one of the plurality of adjustment parameters, respectively, to generate one of a plurality of adjustment filtering results; and

a superposition circuit configured to superpose the plurality of adjusted filtering results as an anti-noise audio; and

an audio playback circuit configured to simultaneously play an actual audio and the anti-noise audio.

2. The audio playback device of claim 1, wherein the audio playback circuit is disposed inside a housing, the radio circuit is an internal radio circuit disposed inside the housing, the radio audio is an internal radio audio, and the audio playback device further comprises:

an analog-to-digital conversion circuit configured to perform analog-to-digital conversion on the internal reception audio;

the subtracting circuit is configured to subtract a part of the internal radio frequency corresponding to the actual frequency, and the plurality of first-order all-pass filtering units connected in series and the adjusting parameter generating circuit respectively filter and generate the plurality of adjusting parameters according to an actual internal radio frequency after subtraction.

3. The audio playback device of claim 2, wherein the plurality of first-order all-pass filtering units connected in series filter a feed radio audio generated by subtracting a portion corresponding to the anti-noise audio from the actual internal radio audio received in practice, and the audio playback device further comprises:

a first response simulation circuit configured to filter the feed radio audio according to a frequency response between the audio playing circuit and the internal radio circuit to generate a filtered radio audio; and

a frequency warping delay circuit, comprising a plurality of first-order all-pass filtering delay units connected in series, configured to perform filtering delay in sequence according to the filtered received audio to generate a plurality of delay results;

wherein the tuning parameter generating circuit actually generates the tuning parameters according to the delay results, the actual internal audio frequency and the previous tuning parameters.

4. The audio playback device of claim 2, further comprising a second response simulation circuit configured to filter the actual audio according to a frequency response between the audio playback circuit and the internal sound pickup circuit to generate a simulated actual audio, and the subtraction circuit is configured to subtract the simulated actual audio from the internal sound pickup audio to generate the actual internal sound pickup audio.

5. The audio playback device of claim 1, wherein the audio playback circuit is disposed inside a housing, the radio circuit is an external radio circuit disposed outside the housing, the radio audio is an external radio audio, and the audio playback device further comprises:

a first analog-to-digital conversion circuit configured to perform analog-to-digital conversion on the external reception audio.

6. The audio playback device of claim 5, wherein the audio playback device further comprises a fixed-coefficient enhancement filter for performing enhancement filtering on the analog-to-digital converted external reception audio.

7. The audio playback device of claim 5, further comprising:

an internal radio circuit disposed inside the housing and configured to receive an internal radio audio;

a second analog-to-digital conversion circuit configured to perform analog-to-digital conversion on the internal reception audio; and

a subtraction circuit configured to subtract a portion of the internal received audio corresponding to the actual audio to generate an actual internal received audio;

wherein the tuning parameter generating circuit is configured to generate the plurality of tuning parameters according to the external received audio and the actual internal received audio after analog-to-digital conversion and enhancement filtering.

8. The audio playback device of claim 7, further comprising:

a first response simulation circuit configured to filter the external radio audio according to a frequency response between the audio playing circuit and the internal radio circuit to generate a filtered radio audio; and

a frequency warping delay circuit, which comprises a plurality of first-order all-pass filtering delay units connected in series and is configured to carry out filtering delay in sequence according to the filtered received audio to generate a plurality of delay results;

9. The audio playback device of claim 7, further comprising a second response simulation circuit configured to filter the actual audio based on a frequency response between the audio playback circuit and the internal sound pickup circuit to generate a simulated actual audio, and the subtraction circuit is configured to subtract the simulated actual audio from the internal sound pickup audio to generate the actual internal sound pickup audio.

10. An audio playing method applied to an audio playing device with an anti-noise mechanism includes:

enabling a radio circuit to receive a radio audio;

enabling an adjusting parameter generating circuit to generate a plurality of adjusting parameters at least according to the received audio frequency;

a plurality of first-order all-pass filtering units connected in series and contained in a frequency warping filtering circuit are sequentially filtered according to the received audio frequency to generate a plurality of filtering results;

multiplying the received audio frequency and one of the filtering results by one of the adjusting parameters to generate one of a plurality of adjusting filtering results;

a superimposing circuit included in the frequency warping filter circuit superimposes the adjusted filter results as an anti-noise audio; and

an audio playing circuit is enabled to play an actual audio and the anti-noise audio simultaneously.