EP4721422A1

EP4721422A1 - Method and system for volume alignment across speaker units

Info

Publication number: EP4721422A1
Application number: EP23737859.1A
Authority: EP
Inventors: Dongcheng LI
Original assignee: Harman International Industries Inc
Current assignee: Harman International Industries Inc
Priority date: 2023-06-01
Filing date: 2023-06-01
Publication date: 2026-04-08
Also published as: WO2024243953A1; CN121079994A

Abstract

A method and system for volume alignment across a set of speaker units is disclosed. The method comprises the steps of: obtaining a set of volume indexes, each of which is associated with one speaker unit in the set of speaker units and is measured in a pre-conducted measurement; deriving a gain factor based on the set of volume indexes; applying the gain factor to an audio signal to create a gained audio signal, the gained audio signal comprising a set of gained audio signals, each of which is intended to be played on one respective speaker unit.

Description

METHOD AND SYSTEM FOR VOLUME ALIGNMENT ACROSS SPEAKER UNITS

TECHNICAL FIELD

The present disclosure relates generally to a method and a system for volume alignment across speaker units.

BACKGROUND

An immersive sound ecosystem comprising multiple connected speaker units is very popular as the system enables users to enjoy an enriched sound experience, with each speaker unit contributing to a cohesive sound output. However, one of the major challenges in such multi-speaker system is the different volume or loudness among different speaker units. These differences can lead to uneven sound experiences and potentially degrade the overall acoustic performance.
Conventionally, to deliver best sound performance, it is essential to align the volume or loudness of all speaker units in the multi-speaker system to a same level. However, the process of aligning volume or loudness often relies on manual calibration techniques using a microphone, which may be complicated and unreliable. Moreover, such manual calibration techniques may not be able to achieve a maximum volume of the speaker units in a system or group, potentially compromising the true potential of the audio system.
There is a need for a simple, reliable, and efficient method for aligning the volume or loudness of different speaker units in a multi-speaker system. This method aims not only to align the volume or loudness across all speaker units but also to ensure an optimized acoustic performance of all speaker units.

SUMMARY OF THE INVENTION

The present disclosure provides a novel volume alignment method, aiming to substantially simplify volume aligning logic and quickly synchronize the volume of a set of speaker units without relying on microphone calibration. The method can align volumes across a set of speaker units while maximizing the acoustic performance of the set.
According to one aspect of the disclosure, a method for volume alignment across a set of speaker units is provided. The method comprises the steps of: obtaining a set of volume indexes, each of which is associated with one speaker unit in the set of speaker units and is measured in a pre-conducted measurement; deriving a gain factor based on the set of volume indexes; applying the gain factor to an audio signal to create a gained audio signal, the gained audio signal comprising a set of gained audio signals, each of which is intended to be played on one respective speaker unit.
According to another aspect of the disclosure, a method for volume alignment across a set of speaker units is provided. The method comprises the steps of: obtaining a set of volume indexes, each of which is associated with one speaker unit in the set of speaker units; calculating a set of gain factors based on differences between volume indexes in the set of volume indexes, with each of the gain factor being associated with one speaker unit in the set of speaker units; applying each gain factor in the set of gain factors to a respective one from a set of audio signals, thereby creating a set of gained audio signals, wherein each of the set of audio signals is for one respective speaker unit; providing each of the set of gained audio signals to a respective speaker unit in the set of speaker units.
According to another aspect of the disclosure, a method for volume alignment across a set of speaker units is provided. The method comprises the steps of: obtaining a set of volume indexes, each of which is associated with one speaker unit in the set of speaker units; applying a main gain factor to a main audio signal to create a gained main audio signal, the gained main audio signal comprising a set of gained audio signals, each of which is for one respective speaker unit, the main gain factor is dependent on the negative of at least one volume index in the set of volume indexes; providing each of the set of gained audio signals to a respective speaker unit in the set of speaker units; and applying a set of secondary gain factors, with each secondary gain factor being applied to a respective gained audio signal provided to one of the set of speaker units, each of the set of secondary gain factors being dependent on one of the set of volume indexes.
According to another aspect of the present disclosure, a system for volume alignment across a set of speaker units is provided. The system comprises a controller configured to perform the aforesaid claim.
According to still another aspect of the present disclosure, an audio system is provided. The audio system comprises a set of speaker units and the aforesaid system for volume alignment across a set of speaker units.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will be better understood by reference to the following drawings and description. The components shown in the drawings are not necessarily to scale, instead, emphasis should be placed upon the principles illustrated by the disclosure. Moreover, in the figures, like reference numerals designate like parts throughout the drawings.
Fig. 1 is a block diagram illustrating an audio system according to one or more embodiments of the present disclosure;
Fig. 2 is a flow chart illustrating a method for volume alignment across a set of speaker units according to one or more embodiments of the present disclosure;
Fig. 3 illustrates detailed steps for step S21 shown in Fig. 2, according to one or more embodiments of the present disclosure;
Fig. 4 illustrates detailed steps for step S22 shown in Fig. 2, according to one or more embodiments of the present disclosure;
Fig. 5 illustrates a schematic diagram of the audio streams of an audio system according to one or more embodiment of the present disclosure;
Fig. 6 is a flow chart illustrating a method for volume alignment across a set of speaker units according to one or more other embodiments of the present disclosure;
Fig. 7 illustrates detailed steps for step S61 shown in Fig. 6, according to one or more embodiments of the present disclosure;
Fig. 8 illustrates a schematic diagram of the audio streams of an audio system according to one or more embodiment of the present disclosure.
BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, various embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings.
As used herein, the singular forms “a” , “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises” , “comprising” , “includes” and/or “including” , as used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or combinations thereof. As used herein, the term “and/or” and the symbol “/” are meant to include any and all combinations of one or more of the associated listed items. Additionally, while the terms first, second etc., may be used herein to describe various elements, components, steps or calculations, these elements, components, steps, or calculations should not be limited by these terms, rather, these terms are only used to distinguish one element, component, step or calculation from another. For example, a first component may be referred to as a second component, similarly a first calculation may be referred to as a second calculation; likewise, a first step may be referred to as a second step, all without departing from the scope of this disclosure.
To clarify the use in the pending claims and to hereby provide notice to the public, the phrases “at least one of <A> , <B> , ... and <N> ” or “at least one of <A> , <B> , ... <N> , or combinations thereof” are defined by the Applicant in the broadest sense, superseding any other implied definitions herebefore or hereinafter unless expressly asserted by the Applicant to the contrary, to mean one or more elements selected from the group comprising A, B, ... and N, that is to say, any combination of one or more of the elements A, B, ... or N including any one element alone or in combination with one or more of the other elements which may also include, in combination, additional elements not listed.
The present disclosure provides a method and a system for volume alignment across a set of speaker units. The method comprises the steps of: obtaining a set of volume indexes, each of which is associated with one speaker unit in the set of speaker units and is measured in a pre-conducted measurement; deriving a gain factor based on the set of volume indexes; applying the gain factor to an audio signal to create a gained audio signal, the gained audio signal comprising a set of gained audio signals, each of which is intended to be played on one respective speaker unit.
The volume alignment method according to the present disclosure may be simple and fast because the volume indexes are measured in a pre-conducted measurement, eliminating the need for an on-the-spot volume alignment using a microphone, which may be complicated and unreliable. Additionally, each of the volume indexes is representative of or dependent on the volume or loudness of the speaker unit with which it is associated. Thus, the gain factors derived based on based on the set of volume indexes may compensate for the volume or loudness differences between the speaker units.
According to one or more embodiments of the present disclosure, the audio signal comprises a set of audio signals, and the method comprises calculating a set of gain factors based on differences between volume indexes in the set of volume indexes and each gain factor in the set of gain factors, applying each gain factor to a respective one from the set of audio signals, thereby creating the set of gained audio signals. In some embodiments, the method comprises: identifying a lowest volume index in the set of volume indexes, the lowest volume index is associated with the speaker unit having a lowest volume or loudness; calculating each gain factor in the set of gain factors based on a difference between the lowest volume index and the respective volume index in the set of volume indexes.
The differences between volume indexes may be indicative of volume or loudness differences between the speaker units. Therefore, the gain factors calculated based on the differences between the volume indexes may represent tuning amounts that are necessary to compensate for the volume or loudness differences between the speaker units, allowing each speaker unit in the set to output sound at a same level despite loudness differences between the speaker units.
In one or more other embodiments of the present disclosure, the gain factor comprises a main factor that is dependent on the negative of at least one volume index in the set of volume indexes and a set of secondary gain factors that is dependent on one of the set of volume indexes. The method further comprises applying the main gain factor to the audio signal to create a gained main audio signal, and applying the set of secondary gain factors, with each secondary gain factor being applied to a respective gained audio signal provided to one of the set of speaker units. In some embodiments, the method further comprises identifying the lowest volume index in the set of volume indexes, and the main gain factor is dependent on the negative of the lowest volume index.
The set of secondary gain factors may involve tuning amounts used to compensate for the loudness difference between the speaker units, so that they may generate a sound output sound at a same level. Additionally, the main gain factor may involve a tuning amount used to adjust the overall loudness range of the set of gained audio signals to accommodate the set of speaker unit, ensuring relatively high performance for the set of speaker units. In the embodiments where the main gain factor is dependent on the negative of the lowest volume index, the main gain factor may serve to overall adjust the sound output to a same level of volume or loudness as the speaker unit in the set having the lowest volume or loudness. This is the highest possible volume or loudness level to which all the speaker units in the set can be aligned or adjusted, allowing a same level of loudness of the speaker units while achieving the best possible performance of the set of speaker units.
Fig. 1 is a block diagram illustrating an audio system 100 according to one or more embodiments of the present disclosure. The audio system 100 comprises a set of speaker units 122, 124, 126, 128, and 130, and a system 110. The system 110 comprises a controller configured to communicate with each speaker unit in the set of speaker units 122, 124, 126, 128, and 130, and to perform a method for volume alignment across a set of speaker units according to one or more embodiments of the present disclosure. In some embodiments of the present disclosure, the system 110 may be implemented in a device that is separate from each of the speaker units 122, 124, 126, 128, and 130. In some other embodiments of the present disclosure, the system 110 may be integrated in or with the speaker unit 122, as shown in dashed line of Fig. 1.
In the embodiments shown in Fig. 1, the audio system 100 comprises five speaker units 122, 124, 126, 128, and 130. The present disclosure is not limited thereto, and in some other embodiments of the present disclosure, the audio system 100 may comprise any suitable number of speaker units, such as 2, 3, 4, 6, 7, 8, 9 or more speaker units. In some embodiments of the present disclosure, the audio system 100 may be a 2.1 audio system, a 5.1 audio system, a 7.1 audio system, a 5.1.2 audio system, a 7.1.2 audio system, a 5.1.4 audio system, or a 7.1.4 audio system. In some embodiments of the present disclosure, at least one speaker unit in the set of speaker units 122, 124, 126, 128, and 130 has a different model than the others of the set of speaker units 122, 124, 126, 128, and 130.
Typically, an audio system or a set of speaker units may comprise speaker units of different models, and thus there may be different volume or loudness among different speaker units. These differences can lead to uneven sound experiences and potentially degrade the overall acoustic performance. Conventionally, a manual volume or loudness alignment is required when grouping the speaker units together to align the volume or loudness of the speaker units to a same level. Such manual volume or loudness alignment requires a microphone and may be complicated and unreliable.
Fig. 2 is a flow chart illustrating a method for volume alignment across a set of speaker units according to one or more embodiments of the present disclosure. While the method may be described in connection with the audio system 100 as shown in Fig. 1, a skilled person would understand that the method can be applied to any suitable audio system or any suitable set of speaker units.
The method as illustrated in Fig. 2 (or a few steps of the method, such as steps S21 and S22) may be typically performed when the set of speaker units are grouped together or regrouped. The process starts at step S21, where a set of volume indexes is obtained, with each volume index being associated with one speaker unit in the set of speaker units. Each of the volume indexes is a representative of the volume or loudness of the speaker unit with which it is associated. In some embodiments, the volume indexes may be expressed in decibels (dB) . The volume indexes are measured in a pre-conducted measurement, which will be described in detail later. The volume indexes may be pre-stored in any suitable storage location, such as in the speaker units, in a remote computer or server, or in any device the controller of the system 110 can communicate with.
The process then goes to step S22, where a set of gain factors is calculated based on differences between volume indexes in the set of volume indexes. Each of the gain factor is associated with one speaker unit in the set of speaker units. The gain factors are crucial to the method of the present disclosure, as they involve tuning amounts used to compensate each speaker unit in the set of speaker units. Since the volume indexes are representative of the volumes or loudness of the speaker units, the differences between volume indexes may be indicative of volume or loudness differences between the speaker units. Therefore, the gain factors calculated based on the differences between the volume indexes may represent tuning amounts that are necessary to compensate for the volume or loudness differences between the speaker units, and to tune respective speaker unit to a same level.
The steps of S23 and S24 may be performed while the audio system or the set of speaker units is operating. In step S23, each gain factor calculated from step S22 may be applied to an audio signal for a speaker unit with which the gain factor is associated, creating a set of gained audio signals. The gain factor may be applied to the audio signal by using any suitable technique, and detailed description thereof is omitted. In step S24, each gained audio signal in the set of gained audio signals is provided to a respective speaker unit in the set of speaker units. Each gained audio signal in the set of gained audio signals has been compensated for the volume or loudness differences between the speaker units by being applied with a corresponding gain factor, allowing each speaker unit in the set of speaker units to output sound at a same level despite loudness differences between the speaker units.
As described above, the volume indexes may be measured in a pre-conducted measurement. The pre-conducted measurement may be carried out in a laboratory or a factory by professional personnel and/or instruments, ensuring accurate volume indexes, which may result in a reliable volume alignment. Additionally, the method according to the present disclosure may be simple and fast because the volume indexes are measured in a pre-conducted measurement, eliminating the need for an on-the-spot volume alignment using a microphone.
Fig. 3 illustrates detailed steps for step S21 shown in Fig. 2, according to one or more embodiments of the present disclosure. In step S31, the controller of the system 110 communicates with each speaker unit to obtain information about the speaker unit. The information may be any suitable information about the speaker unit, such as serial number or model number of the speaker unit. In step S32, after the information about the speaker units is obtained, the controller searches a pre-stored table that contains correspondence between the information about speaker units and their corresponding volume indexes, to retrieve a volume index for each of the speaker units. In one or more other embodiments of the present disclosure, each speaker unit stores its own volume index, and in the step S21 of Fig. 2, the controller communicates with each of the speaker units and obtains the volume indexes directly from the speaker units.
Fig. 4 illustrates detailed steps for step S22 shown in Fig. 2, according to one or more embodiments of the present disclosure. In step S41, the controller identifies a lowest volume index in the set of volume indexes. The lowest volume index is associated with the speaker unit in the set of speaker units that has a lowest volume or loudness. In step S42, the controller calculates each gain factor in the set of gain factors based on a difference between the lowest volume index and a respective volume index in the set of volume indexes. That is, the gain factor associated with each speaker unit is calculated based on the difference between the lowest volume index and volume index associated with the speaker unit. Thus, the gain factors calculated based on the differences between the lowest volume index and each volume index associated with one speaker unit may represent tuning amounts that are necessary to compensate for the volume or loudness differences between each speaker unit and the speaker units having the lowest volume or loudness. With such a set of gain factors, each speaker unit in the set of speaker units can be adjusted, aligned, or compensated to have a same level of volume or loudness as the speaker unit in the set having the lowest volume or loudness. This is the highest possible volume or loudness level to which all the speaker units in the set can be aligned or adjusted. In this way, the set of speaker units may be volume aligned to a same level while achieve the best possible performance of the set of speaker units.
According to one or more embodiments of the present disclosure, the pre-conducted measurement for measuring or determining the volume indexes may be conducted as follows in a laboratory or a factory.
1. Defining a reference loudness: The reference loudness, which is normally denoted as X dB, can be defined by different standards or use cases. As an example, the reference loudness can be set at 75 dB, which is roughly equivalent to the loudness of normal conversation.
2. Volume Maximization: Set the volume of the speaker unit being tested to its maximum level.
3. Test Signal Input: Input a test signal to the speaker unit. Any suitable test signal may be used. In some embodiments, the test signal may be a Pink Noise signal with a Root Mean Square (RMS) level of -12 dB and a peak factor of -6 dB.
4. Volume Tuning: Tune the volume of the speaker unit or apply a gain factor to the test signal while the test signal is being inputted to the speaker unit, until the loudness received by a microphone specifically positioned relative to the speaker unit matches the reference loudness (e.g., 75 dB) .
5. Value Recording: The tuned dB value or the applied gain value may be recorded as a volume index for the speaker unit or speaker units of the same model. Normally, the recorded value should be negative.
In some embodiments, the recorded volume index may be stored in the speaker unit or all speaker units of a same model. In some other embodiment, volume indexes for speaker unit of each model are recorded and all the volume indexes and their corresponding speaker unit model are then compiled into a Table that contains correspondence between the speaker unit models and their corresponding volume indexes. In some embodiments, the reference loudness may be any suitable loudness as long as it is lower than the loudness of any possible speaker unit measured in the pre-conducted measurement before the step of Volume Tuning, i.e., when the speaker unit is not tuned or no gain factor is applied to the speaker unit.
Fig. 5 illustrates a schematic diagram of the audio streams of an audio system according to one or more embodiment of the present disclosure. An example of the method according to the present disclosure will be described in connection with Fig. 5. The table below shows the volume indexes obtained in step S21 in the example.
As shown in the table, the speaker unit 122 has a volume index of a lowest value, i.e., -20 dB while the speaker unit 130 has a volume index of a highest value, i.e., -5 dB. The volume index of -20 dB means that the speaker unit 122 needs to be tuned by -20 dB or applied a gain factor of -20 dB to match a reference loudness (e.g., 75 dB) , while volume index of -5 dB means that the speaker unit 130 needs to be tuned by -5 dB or applied a gain value of -5 dB to match the reference loudness (e.g., 75 dB) . That is, initially, speaker unit 122 has the highest volume or loudness and the speaker unit 130 has the lowest volume or loudness. Specifically, the speaker unit 122 is initially -5dB - (-20dB) = 15dB louder than speaker unit 130. Similarly, the speaker unit 124 is initially -5dB - (-12dB) = 7 dB louder than speaker unit 130; the speaker unit 126 is initially -5dB - (-9dB) = 4 dB louder than speaker unit 130; and the speaker unit 128 is initially -5dB - (-8dB) = 3 dB louder than speaker unit 130.
In step S22, a set of gain factors is calculated by subtracting the lowest volume index from a respective volume index in the set of volume indexes. Each gain factor is associated with one speaker unit in the set of speaker units. Specifically, the gain factor associated with each speaker unit = the volume index associated with the speaker unit –the lowest volume index. The gain factors associated with each speaker unit are:
the gain factor associated with the speaker unit 122 (channel A gain) = -20dB - (-5dB) = -15dB;
the gain factor associated with the speaker unit 124 (channel B gain) = -12dB - (-5dB) = -7 dB;
the gain factor associated with the speaker unit 126 (channel C gain) = -9dB - (-5dB) = -4dB;
the gain factor associated with the speaker unit 128 (channel D gain) = -8dB - (-5dB) = -3dB;
the gain factor associated with the speaker unit 130 (channel Z gain) = -5dB - (-5dB) = 0dB.
In step S23, each gain factor calculated from step S22 is applied to an audio signal for a speaker unit with which the gain factor is associated, creating a set of gained audio signals. Specifically, the channel A gain of -15dB is applied to the audio signal or signal channel (channel A) to be provided to the speaker unit 122; the channel B gain of -7 dB is applied to the audio signal or signal channel (channel B) to be provided to the speaker unit 124; the channel C gain of -4dB is applied to the audio signal or signal channel (channel C) to be provided to the speaker unit 126; the channel D gain of -3dB is applied to the audio signal or signal channel (channel D) to be provided to the speaker unit 128; and the channel Z gain of 0dB, i.e., no gain factor, is applied to the audio signal or signal channel (channel Z) to be provided to the speaker unit 130, as shown in Fig. 5.
In step S24, each gained audio signal in the set of gained audio signals is provided to a respective speaker unit in the set of speaker units. Specifically, the audio signal of the channel A is provided to the speaker unit 122; the audio signal of the channel B is provided to the speaker unit 124; the audio signal of the channel C is provided to the speaker unit 126, the audio signal of channel D is provided to the speaker unit 128, and the audio signal of channel Z is provided to the speaker unit 130.
Therefore, the volume or loudness differences between the speaker units 122, 124, 126, 128, and 130 have been completely compensated, allowing all the speaker units to output sound at a same level despite their initial loudness differences. Additionally, no gain factor has been applied to the speaker unit 130, which has the lowest volume or loudness, allowing the speaker unit 130 to work or operate at its highest performance, and thus ensuring the highest possible performance of the set of speaker units.
Fig. 6 is a flow chart illustrating a method for volume alignment across a set of speaker units according to one or more other embodiments of the present disclosure. While the method may be described in connection with the audio system 100 as shown in Fig. 1, a skilled person would understand that the method can be applied to any suitable audio system or any suitable set of speaker units.
The method as illustrated in Fig. 6, or only the first step S61 of the method, may be typically performed when the set of speaker units are grouped together or regrouped. The process starts at step S61, where a set of volume indexes is obtained, with each volume index being associated with one speaker unit in the set of speaker units. Each of the volume indexes is dependent on or positively correlated with the volume or loudness of the speaker unit with which it is associated. In one or more embodiments, each of the volume indexes is representative of a volume or loudness difference between the speaker unit with which it is associated and a virtual speaker unit. The virtual speaker unit may have a loudness higher than or equal to any possible speaker unit that may be grouped in the set of speaker unit. In some embodiments, the volume indexes may be expressed in decibels (dB) . The volume indexes may be measured and defined in a pre-conducted measurement, which will be described in detail later. The volume indexes may be pre-stored in any suitable storage location, such as in its respective speaker unit, in a remote computer or server, or in any device the controller of the system 110 can communicate with.
The steps of S62-S64 may be performed while the audio system or the set of speaker units is operating. In step S62, a main gain factor is applied to a main audio signal, which in some embodiments may be an audio signal received from an external audio source. This produces a gained main audio signal, which may comprise a set of gained audio signals, each of which is for one respective speaker unit. In some embodiments, the main gain factor may be dependent on or positively correlated with the negative of at least one volume index in the set of volume indexes.
In step S63, each gained audio signal in the set of gained audio signals is provided to a respective speaker unit in the set of speaker units. In step S64, a set of secondary gain factors is applied, with each secondary gain factor being applied to a respective gained audio signal provided to one of the set of speaker units. Each of the set of secondary gain factors is dependent on or positively correlated with one of the set of volume indexes.
Each of the volume indexes is dependent on or positively correlated with the volume or loudness of the speaker unit with which it is associated, while each of the set of secondary gain factors being dependent on or positively correlated with one of the set of volume indexes. In one or more embodiments, each of the volume indexes is representative of a volume or loudness difference between the speaker unit with which it is associated and a virtual speaker unit. Thus, the set of secondary gain factors may involve tuning amounts used to compensate for the loudness difference between the speaker units, so that they may generate a sound output sound at a same level. Moreover, the main gain factor is dependent on or positively correlated with the negative of at least one volume index in the set of volume indexes. The main gain factor may involve a tuning amount used to adjust the overall loudness range of the set of gained audio signals to accommodate the set of speaker unit, ensuring relatively high performance for the set of speaker units.
According to one or more embodiments of the present disclosure, the method comprises identifying the lowest volume index in the set of volume indexes, which is associated with the speaker unit having a lowest volume or loudness. The main gain factor is dependent or positively correlated with on the negative of the lowest volume index. In some embodiment, the main gain factor is equal to the negative of the lowest volume index, and/or each of the set of secondary gain factors is equal to one of the set of volume indexes.
By using such a main gain factor, the overall loudness range of the set of gained audio signals can be adjusted to best accommodate the set of speaker unit. Specifically, the set of secondary gain factors may compensate for the loudness difference between the speaker units to have a sound output at a same level while the main gain factor serves to overall adjust the sound output to a same level of volume or loudness as the speaker unit in the set having the lowest volume or loudness. This is the highest possible volume or loudness level to which all the speaker units in the set can be aligned or adjusted. In this way, the set of speaker units may be volume aligned to a same level of volume or loudness while achieving the best possible performance of the set of speaker units.
As described above, the volume indexes may be measured in a pre-conducted measurement. The pre-conducted measurement may be carried out in a laboratory or a factory by professional personnel and/or instruments, ensuring accurate volume indexes which may result in a reliable volume alignment. Additionally, the method according to the present disclosure may be simple and fast because the volume indexes are measured in a pre-conducted measurement, eliminating the need for an on-the-spot volume alignment using a microphone.
Fig. 7 illustrates detailed steps for step S61 shown in Fig. 6, according to one or more embodiments of the present disclosure. In step S71, the controller of the system 110 communicates with each speaker unit to obtain information about the speaker unit. The information may be any suitable information about the speaker unit, such as serial number or model number of the speaker unit. In step S72, after the information about the speaker units is obtained, the controller searches a pre-stored table that contains correspondence between the information about speaker units and their corresponding volume indexes, to retrieve a volume index for each of the speaker units. In one or more other embodiments of the present disclosure, each speaker unit stores its own volume index, and in the step S61 of Fig. 6, the controller communicates with each of the speaker units and obtains the volume indexes directly from the speaker units.
In one or more embodiments of the present disclosure, each of the set of secondary gain factors (volume indexes) is pre-stored or solidified in a respective speaker unit. When a speaker unit works or operates in a stand-alone manner, the secondary gain factor is not applied. On the other hand, when the speaker unit is grouped with other speaker units, the pre-stored or solidified secondary gain factor is applied to the audio signal during operation. This means when the speaker units 122, 124, 126, 128, and 130 are grouped together, each speaker unit 122, 124, 126, 128, and 130 applies its pre-stored or solidified secondary gain factor to the audio signal it receives. Thus, the system 110 only needs to calculate and apply one gain factor, i.e., the main gain factor, which is easier and simpler.
According to one or more embodiments of the present disclosure, the pre-conducted measurement for measuring or determining the volume indexes may be conducted as follows in a laboratory or a factory.
1. Defining a reference loudness: The reference loudness, which is normally denoted as X dB, can be defined by different standards or use cases. As an example, the reference loudness can be set at 75 dB, which is roughly equivalent to the loudness of normal conversation.
2. Volume Maximization: Set the volume of the speaker unit being tested to its maximum level.
3. Test Signal Input: Input a test signal to the speaker unit. Any suitable test signal may be used. In some embodiments, the test signal may be a Pink Noise signal with a Root Mean Square (RMS) level of -12 dB and a peak factor of -6 dB.
4. Volume Tuning: Tune the volume of the speaker unit or apply a gain factor to the test signal while the test signal is being inputted to the speaker unit, until the loudness received by a microphone specifically positioned relative to the speaker unit matches the reference loudness (e.g., 75 dB) .
5. Defining a preset gain factor: The preset gain factor represents a tuning factor of a virtual speaker unit that has a volume or loudness higher than or equal to any possible speaker unit that may be grouped in the set of speaker units.
6. Value Recording: Recording the volume index of the speaker unit being testing as a difference between the tuned value of the speaker unit derived in step of Volume Tuning with the preset gain factor. For example, the volume index is derived by subtracting the preset gain factor from the tuned value of the speaker unit. Normally, the recorded value should be positive.
In some embodiments, the recorded volume index may be stored in the speaker unit or all speaker units of the same model. In some other embodiment, volume indexes for all models of the speaker units are recorded and all the volume indexes and their corresponding speaker unit model are then compiled into a Table that contains correspondence between the speaker unit models and their corresponding volume indexes. In some embodiments, the reference loudness may be any suitable loudness as long as it is lower than the loudness of any possible speaker unit measured in the pre-conducted measurement before the step of Volume Tuning, i.e., when the speaker unit is not tuned or no gain factor is applied to the speaker unit.
Fig. 8 illustrates a schematic diagram of the audio streams of an audio system according to one or more embodiment of the present disclosure. An example of the method according to the present disclosure will be described in connection with Fig. 8. The table below shows an example of the tuned values obtained in the above step of Volume Tuning.
As shown in the table, the speaker unit 122 has a tuned value of a lowest value, i.e., -20 dB while the speaker unit 130 has a tuned value of a highest value, i.e., -5 dB. The tuned value of -20 dB means that the speaker unit 122 needs to be tuned by -20 dB or applied a gain factor of -20 dB to match a reference loudness (e.g., 75 dB) , while tuned value of -5 dB means that the speaker unit 130 needs to be tuned by -5 dB or applied a gain value of -5 dB to match the reference loudness (e.g., 75 dB) . That is, initially, speaker unit 122 has the highest volume or loudness and the speaker unit 130 has the lowest volume or loudness. Specifically, the speaker unit 122 is initially -5dB - (-20dB) = 15dB louder than speaker unit 130. Similarly, the speaker unit 124 is initially -5dB - (-12dB) = 7 dB louder than speaker unit 130; the speaker unit 126 is initially -5dB - (-9dB) = 4 dB louder than speaker unit 130; and the speaker unit 128 is initially -5dB - (-8dB) = 3 dB louder than speaker unit 130.
In this example, the preset gain factor is defined as -30 dB, which is lower than any of the tuned values of the speaker units 122, 124, 126, 128, and 130. This means the virtual speaker unit represented by the present gain factor has a volume or loudness higher than any of the speaker units 122, 124, 126, 128, and 130.
The table below shows the volume indexes in the example.
In step S62, a main gain factor is applied to a main audio signal. In the example, the main gain factor is equal to the negative of the lowest volume index, which is the volume index of the speaker unit having a lowest volume or loudness, i.e., the speaker unit 130. Thus, the main factor is equal to -25 dB.
In step S63, each gained audio signal in the set of gained audio signals is provided to a respective speaker unit in the set of speaker units. Specifically, the channel A signal is provided to the speaker unit 122, the channel B signal is provided to the speaker unit 124, the channel C signal is provided to the speaker unit 126, the channel D signal is provided to the speaker unit 128, and the channel Z signal is provided to the speaker unit 130.
In step S64, each of the speaker units 122, 124, 126, 128, and 130 applies a secondary gain factor to the audio signal it receives. In the example, each secondary gain factor applied by a speaker unit 122, 124, 126, 128, and 130 is equal to the volume index associated with the speaker unit. That is, the secondary gain factor applied by the speaker 122 (AGain) is 10 dB, the secondary gain factor applied by the speaker 124 (B Gain) is 18 dB, the secondary gain factor applied by the speaker 126 (C Gain) is 21 dB, the secondary gain factor applied by the speaker 128 (D Gain) is 22 dB, and the secondary gain factor applied by the speaker 130 (Z Gain) is 25 dB.
Thus, the total gain factor associated with each speaker unit is:
the total gain factor associated with the speaker unit 122 = main gain factor +secondary gain factor for speaker 122 (Again) = -25dB + 10dB= -15dB;
the total gain factor associated with the speaker unit 124 = main gain factor +secondary gain factor for speaker 124 (B gain) = -25dB + 18dB= -7dB;
the total gain factor associated with the speaker unit 126 = main gain factor +secondary gain factor for speaker 126 (C gain) = -25dB + 21dB= -4dB;
the total gain factor associated with the speaker unit 128 = main gain factor +secondary gain factor for speaker 128 (D gain) = -25dB + 22dB= -3dB;
the total gain factor associated with the speaker unit 130 = main gain factor +secondary gain factor for speaker 130 (Z gain) = -25dB + 25dB= 0dB.
Therefore, the volume or loudness differences between the speaker units 122, 124, 126, 128, and 130 have been completely compensated by the combination of the main gain factor and the set of second gain factors, allowing all the speaker units to output a sound at a same level despite their initial loudness differences. Additionally, the total gain factor associated with the speaker unit 130 is 0dB, that is, no gain factor has been applied to the speaker unit 130, which has the lowest volume or loudness, allowing the speaker unit 130 to work or operate at its highest performance, and thus ensuring the highest possible performance of the set of speaker units.
The present disclosure is not limited to the embodiments shown in Figs. 1-5 and the embodiments of Figs. 6-8. For example, any suitable gain factor which is derived based on the set of volume indexes may be used to compensate the volume or loudness differences between the speaker units. The gain factor may also be applied to the audio signal in any suitable way. In one or more embodiments of the present disclosure, the method for volume alignment across a set of speaker units may be implemented as comprising the steps of: obtaining a set of volume indexes, each of which is associated with one speaker unit in the set of speaker units and is measured in a pre-conducted measurement; deriving a gain factor based on the set of volume indexes; applying the gain factor to an audio signal to create a gained audio signal, the gained audio signal comprising a set of gained audio signals, each of which is intended to be played on one respective speaker unit.
The method according to the present disclosure may be simple and fast because the volume indexes are measured in a pre-conducted measurement, eliminating the need for an on-the-spot volume alignment using a microphone, which may be complicated and unreliable.
According to one or more embodiments of the disclosure, the present disclosure can be implemented as follows.
Item 1: A method for volume alignment across a set of speaker units, comprising the steps of: obtaining a set of volume indexes, each of which is associated with one speaker unit in the set of speaker units and is measured in a pre-conducted measurement; deriving a gain factor based on the set of volume indexes; applying the gain factor to an audio signal to create a gained audio signal, the gained audio signal comprising a set of gained audio signals, each of which is intended to be played on one respective speaker unit.
Item 2: The method of Item 1, wherein the audio signal comprises a set of audio signals, and the step of deriving a gain factor comprises calculating a set of gain factors based on differences between volume indexes in the set of volume indexes, with each of the gain factor being associated with one speaker unit in the set of speaker units; the step of applying the gain factor to an audio signal comprises applying each gain factor in the set of gain factors to a respective one from the set of audio signals, thereby creating the set of gained audio signals; the method further comprises providing each of the set of gained audio signals to a respective speaker unit in the set of speaker units.
Item 3: The method of any one of Items 1-2, wherein the step of calculating a set of gain factors comprises: identifying a lowest volume index in the set of volume indexes, the lowest volume index is associated with the speaker unit having a lowest volume or loudness; calculating each gain factor in the set of gain factors based on a difference between the lowest volume index and the respective volume index in the set of volume indexes.
Item 4: The method of any one of Items 1-3, wherein each gain factor in the set of gain factors is calculated by subtracting the lowest volume index from a respective volume index in the set of volume indexes.
Item 5: The method of any one of Items 1-4, wherein each volume index in the set of volume indexes is a measured gain factor for a respective speaker unit, by which the speaker unit is tuned to output a reference loudness while receiving a reference audio signal.
Item 6: The method of any one of Items 1-5, wherein the gain factor comprises a main factor and a set of secondary gain factors,
the step of applying the gain factor comprises: applying the main gain factor to the audio signal to create a gained main audio signal, the gained main audio signal comprising a set of gained audio signals, each of which is for one respective speaker unit, the main gain factor is dependent on the negative of at least one volume index in the set of volume indexes, wherein the method further comprises providing each of the set of gained audio signals to a respective speaker unit in the set of speaker units, the step of applying the gain factor further comprises: applying the set of secondary gain factors, with each secondary gain factor being applied to a respective gained audio signal provided to one of the set of speaker units, each of the set of secondary gain factors being dependent on one of the set of volume indexes.
Item 7: The method of any one of Items 1-6, further comprising: identifying the lowest volume index in the set of volume indexes, the lowest volume index being associated with the speaker unit having a lowest volume or loudness, the main gain factor is dependent on the negative of the lowest volume index.
Item 8: The method of any one of Items 1-7, wherein the main gain factor is equal to the negative of the lowest volume index.
Item 9: The method of any one of Items 1-8, wherein each of the set of secondary gain factors is equal to one of the set of volume indexes.
Item 10: The method of any one of Items 1-9, wherein each volume index in the set of volume indexes is derived by subtracting a preset gain factor from a measured gain factor for a respective speaker unit, wherein the respective speaker unit is tuned by the measured gain factor to output a reference loudness while receiving a reference audio signal, and the preset gain factor represents a loudness no lower than any possible speaker unit that may be grouped in the set of speaker units.
Item 11: The method of any one of Items 1-10, wherein each of the set of secondary gain factors is pre-stored in a respective speaker unit, which applies its secondary gain factor to the gained audio signal it receives.
Item 12: The method of any one of Items 1-11, wherein the step of obtaining a set of volume indexes comprises: communicating with each speaker unit in the set of speaker units to obtain information about the speaker unit; retrieving each volume index in the set of volume indexes by searching a table that contains correspondence between the information about speaker units and their corresponding volume indexes.
Item 13: The method of any one of Items 1-12, wherein the step of obtaining a set of volume indexes comprises: communicating with each speaker unit in the set of speaker units to obtain the volume index pre-stored in the speaker unit.
Item 14: The method of any one of Items 1-13, wherein each volume index and/or each gain factor is represented as a decibel value.
Item 15: The method of any one of Items 1-14, wherein at least one volume index in the set of volume indexes is different from others in the set of volume indexes.
Item 16: The method any one of Items 1-15, wherein the set of speaker units are speaker units in an audio system and the set of audio signals are different audio channel signals for respective speaker units.
Item 17: A system for volume alignment across a set of speaker units, the system comprises a controller configured to perform any one of Items 1-16.
Item 18: The system of Item 17, wherein the system is implemented in a device separate from the set of speaker units or is integrated in one of the set of speaker unit.
Item 19: An audio system, comprising a set of speaker units and a system for volume alignment across a set of speaker units of any one of Items 17-18.
Item 20: The audio system of Item 19, wherein the audio system is a 2.1 audio system, 5.1 audio system, 7.1 audio system, 5.1.2 audio system, 7.1.2 audio system, 5.1.4 audio system, or 7.1.4 audio system.
Systems and methods have been described in general terms as an aid to understanding details of the disclosure. In some instances, well-known structures, materials, and/or operations have not been specifically shown or described in detail to prevent obscuring aspects of the disclosure. In other instances, specific details have been given to provide a thorough understanding of the disclosure. One skilled in the relevant art will recognize that the disclosure may be embodied in other specific forms, for example to adapt to a particular system or apparatus or situation or material or component, without departing from the spirit or essential characteristics thereof. Therefore, the disclosures and descriptions herein are intended to be illustrative, but not limiting, of the scope of the disclosure. Accordingly, the disclosure is not to be restricted except considering the attached claims and their equivalents.

Claims

A method for volume alignment across a set of speaker units, comprising the steps of:

obtaining a set of volume indexes, each of which is associated with one speaker unit in the set of speaker units and is measured in a pre-conducted measurement;

deriving a gain factor based on the set of volume indexes;

applying the gain factor to an audio signal to create a gained audio signal, the gained audio signal comprising a set of gained audio signals, each of which is intended to be played on one respective speaker unit.
The method of claim 1, wherein the audio signal comprises a set of audio signals, and

the step of deriving a gain factor comprises calculating a set of gain factors based on differences between volume indexes in the set of volume indexes, with each of the gain factor being associated with one speaker unit in the set of speaker units;

the step of applying the gain factor to an audio signal comprises applying each gain factor in the set of gain factors to a respective one from the set of audio signals, thereby creating the set of gained audio signals;

the method further comprises providing each of the set of gained audio signals to a respective speaker unit in the set of speaker units.
The method of claim 2, wherein the step of calculating a set of gain factors comprises:

identifying a lowest volume index in the set of volume indexes, the lowest volume index is associated with the speaker unit having a lowest volume or loudness;

calculating each gain factor in the set of gain factors based on a difference between the lowest volume index and the respective volume index in the set of volume indexes.
The method of clam 3, wherein each gain factor in the set of gain factors is calculated by subtracting the lowest volume index from a respective volume index in the set of volume indexes.
The method of claim 2, wherein each volume index in the set of volume indexes is a measured gain factor for a respective speaker unit, by which the speaker unit is tuned to output a reference loudness while receiving a reference audio signal.
The method of claim 1, wherein the gain factor comprises a main factor and a set of secondary gain factors,

the step of applying the gain factor comprises: applying the main gain factor to the audio signal to create a gained main audio signal, the gained main audio signal comprising a set of gained audio signals, each of which is for one respective speaker unit, the main gain factor is dependent on the negative of at least one volume index in the set of volume indexes,

wherein the method further comprises providing each of the set of gained audio signals to a respective speaker unit in the set of speaker units,

the step of applying the gain factor further comprises: applying the set of secondary gain factors, with each secondary gain factor being applied to a respective gained audio signal provided to one of the set of speaker units, each of the set of secondary gain factors being dependent on one of the set of volume indexes.
The method of claim 6, further comprising

identifying the lowest volume index in the set of volume indexes, the lowest volume index being associated with the speaker unit having a lowest volume or loudness, the main gain factor is dependent on the negative of the lowest volume index.
The method of claim 7, wherein the main gain factor is equal to the negative of the lowest volume index.
The method of claim 6, wherein each of the set of secondary gain factors is equal to one of the set of volume indexes.
The method of claim 6, wherein each volume index in the set of volume indexes is derived by subtracting a preset gain factor from a measured gain factor for a respective speaker unit, wherein the respective speaker unit is tuned by the measured gain factor to output a reference loudness while receiving a reference audio signal, and the preset gain factor represents a loudness no lower than any possible speaker unit that may be grouped in the set of speaker units.
The method of claim 6, wherein each of the set of secondary gain factors is pre-stored in a respective speaker unit, which applies its secondary gain factor to the gained audio signal it receives.
The method of any one of claims 1-11, wherein the step of obtaining a set of volume indexes comprises:

communicating with each speaker unit in the set of speaker units to obtain information about the speaker unit;

retrieving each volume index in the set of volume indexes by searching a table that contains correspondence between the information about speaker units and their corresponding volume indexes.
The method of any one of claims 1-11, wherein the step of obtaining a set of volume indexes comprises:

communicating with each speaker unit in the set of speaker units to obtain the volume index pre-stored in the speaker unit.
The method of any one of claims 1-11, wherein each volume index and/or each gain factor is represented as a decibel value.
The method of any one of claims 1-11, wherein at least one volume index in the set of volume indexes is different from others in the set of volume indexes.
The method any one of claims 1-11, wherein the set of speaker units are speaker units in an audio system and the set of audio signals are different audio channel signals for respective speaker units.
A system for volume alignment across a set of speaker units, the system comprises a controller configured to perform any one of claims 1-16.
The system of claim 17, wherein the system is implemented in a device separate from the set of speaker units or is integrated in one of the set of speaker unit.
An audio system, comprising a set of speaker units and a system for volume alignment across a set of speaker units of any one of claims 17-18.
The audio system of claim 19, wherein the audio system is a 2.1 audio system, 5.1 audio system, 7.1 audio system, 5.1.2 audio system, 7.1.2 audio system, 5.1.4 audio system, or 7.1.4 audio system.