EP3621314A1 - Processeur audio et procédé de traitement d'un signal audio - Google Patents

Processeur audio et procédé de traitement d'un signal audio Download PDF

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Publication number
EP3621314A1
EP3621314A1 EP18192859.9A EP18192859A EP3621314A1 EP 3621314 A1 EP3621314 A1 EP 3621314A1 EP 18192859 A EP18192859 A EP 18192859A EP 3621314 A1 EP3621314 A1 EP 3621314A1
Authority
EP
European Patent Office
Prior art keywords
audio signal
audio
processor
power
frequencies
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP18192859.9A
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German (de)
English (en)
Inventor
Ísmail YILMAZLAR
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Vestel Elektronik Sanayi ve Ticaret AS
Original Assignee
Vestel Elektronik Sanayi ve Ticaret AS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Vestel Elektronik Sanayi ve Ticaret AS filed Critical Vestel Elektronik Sanayi ve Ticaret AS
Priority to EP18192859.9A priority Critical patent/EP3621314A1/fr
Publication of EP3621314A1 publication Critical patent/EP3621314A1/fr
Pending legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers, loudspeakers or microphones
    • H04R3/04—Circuits for transducers, loudspeakers or microphones for correcting frequency response
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2430/00—Signal processing covered by H04R, not provided for in its groups
    • H04R2430/03—Synergistic effects of band splitting and sub-band processing

Definitions

  • the present disclosure relates to an audio processor and a method of processing an audio signal.
  • a problem that often occurs with sound reproduction apparatus is that some part of the apparatus, such as a cabinet or casing or the like, vibrates during playback of audio.
  • Common solutions to this include fitting vibration dampeners, such as felt or rubber pads or the like, tightening screws or the like that hold the cabinet together, or simply turning down the playback volume.
  • vibration dampeners such as felt or rubber pads or the like
  • tightening screws or the like that hold the cabinet together, or simply turning down the playback volume.
  • such solutions are often not convenient for the manufacturer and/or user of the apparatus.
  • a method of processing an audio signal comprising:
  • the reduction of the power, in particular the instantaneous power, of the input audio signal at the resonant audio frequency can reduce or even entirely eliminate the resonance being caused to some sound reproduction apparatus and therefore the vibration or buzzing that can occur.
  • the increase of the power of the input audio signal at at least some other audio frequencies can help to "disguise" the reduction of the power at the resonant frequency, which makes the reduction in volume at the resonant frequency less noticeable for the user.
  • the resonant frequency is a resonant frequency of a cabinet in which the loudspeaker is mounted, the resonant frequency being identified using a vibration sensor which is attached to a cabinet in which the loudspeaker is mounted.
  • the output of the vibration sensor is subject to a Fast Fourier Transform FFT to identify the resonant frequency.
  • the total or average power of the output audio signal is substantially the same as the total or average power of the input audio signal.
  • the total or average power of the output audio signal may be within around 5% of the total or average power of the input audio signal.
  • the other audio frequencies are frequencies that are within 5% of the resonant frequency. In an example, the other audio frequencies are frequencies that are within 2% of the resonant frequency.
  • an audio processor for processing an input audio signal, the audio processor being arranged to: process an input audio signal to provide an audio signal to be output to a loudspeaker, wherein the processor is configured such that the processing of the input audio signal reduces the power of the input audio signal at a resonant audio frequency and increases the power of the input audio signal at at least some other audio frequencies other than the resonant audio frequency.
  • the processor is arranged to obtain the resonant frequency from data storage in which the resonant frequency is stored.
  • the processor is arranged to obtain the resonant frequency using a vibration sensor which is attached to a cabinet in which said loudspeaker is mounted.
  • the output of the vibration sensor is arranged to be subject to a Fast Fourier Transform FFT to identify the resonant frequency.
  • the processor is configured such that the total or average power of the output audio signal is substantially the same as the total or average power of the input audio signal.
  • the processor is configured such that the other audio frequencies are frequencies that are within 5% of the resonant frequency.
  • a sound reproduction apparatus comprising an audio processor as described above and at least one loudspeaker which is arranged to receive an output audio signal which is output by the audio processor.
  • Examples of the present disclosure are applicable to audio processors for various types of sound reproduction apparatus as well as being applicable to various types of sound reproduction apparatus.
  • Such sound reproduction apparatus typically includes one or more loudspeakers.
  • the term "loudspeaker” is in general used to describe an electroacoustic transducer which converts an electrical audio signal into a corresponding sound.
  • the loudspeaker may be of the "dynamic cone speaker” type having a diaphragm or cone which is driven to move by a voice coil.
  • the loudspeaker may be of another type, including for example a magnetostatic speaker, an electrostatic loudspeaker, etc.
  • the sound reproduction apparatus may be a standalone system, such as a combination of one or more speakers with a separate sound processing unit, or an integrated system of speakers and sound processing unit (often called a "sound bar” or the like).
  • the sound reproduction apparatus may be provided as part of some other equipment, such as a television set, a computer, especially a laptop or notebook computer or the like, etc., which has integral and/or separate speakers.
  • a problem that often occurs with sound reproduction apparatus is that some part of the apparatus, such as a cabinet or casing or the like, vibrates during playback of audio, often giving rise to an audible buzzing of the equipment. This is usually because of some resonance occurring at one or more resonant frequencies during audio playback. This is often some resonance occurring in the cabinet or casing in which the speakers are housed or some adjacent part of the cabinet or casing owing to the natural frequency of the cabinet or casing or the like being excited.
  • vibration dampeners such as felt or rubber pads or the like
  • tightening screws or the like that hold the cabinet together.
  • This may be carried out by the manufacturer of the sound reproduction apparatus as a final step in the manufacturing process.
  • the resonant frequency may change over time and/or when the sound reproduction apparatus is deployed by the end consumer or other user.
  • End consumers or other users may try to fit vibration dampeners or tighten up loose parts of the cabinet, etc., but this is inconvenient and troublesome for the user.
  • Another option for the end user is simply to turn down the playback volume, but inevitably this spoils the enjoyment of the apparatus for the user.
  • an input audio signal is processed to provide an audio signal to be output to a loudspeaker.
  • the processing of the input audio signal reduces the power of the input audio signal at a resonant audio frequency and increases the power of the input audio signal at at least some other audio frequencies other than the resonant audio frequency.
  • the reduction of the power, in particular the instantaneous power, of the input audio signal at the resonant audio frequency can reduce or even entirely eliminate the resonance being caused to some sound reproduction apparatus and therefore the vibration or buzzing that can occur.
  • the increase of the power of the input audio signal at at least some other audio frequencies can help to "disguise" the reduction of the power at the resonant frequency, which makes the reduction in volume at the resonant frequency less noticeable for the user.
  • the other audio frequencies, for which the power is increased may be frequencies close to or adjacent to the resonant frequency.
  • the total or average power of the output audio signal is substantially the same as the total or average power of the input audio signal.
  • FIG. 1 shows a schematic block diagram of an example of an audio processing arrangement 10 according to the present disclosure.
  • the audio processing arrangement 10 has an audio processor 12.
  • the audio processor 12 receives as an input an input audio signal 14.
  • the audio processor 12 processes the input audio signal 14 and outputs an output audio signal 16.
  • the output audio signal 16 may then be passed to a separate amplifier to be amplified as required before being passed to one or more speakers for audio playback.
  • the audio processor 12 may itself already amplify the output audio signal 16 as necessary.
  • the input audio signal 14 may be provided from one of a number of audio sources, depending on for example the equipment in which the audio processor 12 is used.
  • the input audio signal 14 may be provided by a television broadcast signal (whether satellite, cable or terrestrial), or by a DVD player or Internet source, etc., which is feeding the television set.
  • the input audio signal 14 may be provided from files stored on the computer, such as video or audio files.
  • the input audio signal 14 may be provided by a CD or MP3 or other audio or media player. Other examples of sources for the input audio signal 14 are possible.
  • Figure 1 also shows the audio processing arrangement 10 having a vibration sensor 18 which provides an output to a processing block 20 which in turn processes the output of the vibration sensor 18 to identify one or more resonant frequencies.
  • the processing block 20 may be provided as part of the audio processor 12. There may be a single vibration sensor 18 or plural vibration sensors 18, located at different positions, may be used.
  • the senor 18 and the processing block 20 in some examples are only used during a manufacturing stage to identify one or more resonant frequencies at the time of manufacture.
  • the audio processor 12 needs to be incorporated into a sound reproduction apparatus for end use by a user.
  • the senor 18 and the processing block 20 are incorporated with the audio processor 12 into a sound reproduction apparatus for end use by a user.
  • the vibration sensor 18 is fitted to some part of the sound reproduction apparatus to allow one or more resonant frequencies of the sound reproduction apparatus to be determined.
  • the vibration sensor 18 outputs an electrical signal that corresponds to vibration of the sound reproduction apparatus which occurs when sound is being output.
  • a particularly suitable vibration sensor for this purpose is a piezoelectric transducer, though other vibration sensors, including other electroacoustic transducers, may be used.
  • the processing block 20 receives the output of the vibration sensor 18 and processes it to identify one or more resonant frequencies of the sound reproduction apparatus when sound is being output. A number of techniques for this are possible. A suitable technique is for the processing block 20 to carry out a Fast Fourier Transform (FFT) to identify the resonant frequency or frequencies.
  • FFT Fast Fourier Transform
  • An FFT samples a signal over a period of time and divides it into its frequency components. These components are single sinusoidal oscillations at distinct frequencies each with their own power or amplitude (and phase).
  • a sound reproduction apparatus 30 such as a television set, a computer, a sound processing unit, etc., has a cabinet or casing 32 in which are mounted a main processor 34 and data storage 36.
  • the sound reproduction apparatus 30 has integral loudspeakers 38.
  • the loudspeakers 38 are provided separately and connected to the sound reproduction apparatus 30 using wired and/or wireless connections.
  • the sound reproduction apparatus 30 also has an audio processor 12 as described herein. This may be a separate processor or its function may be provided by the main processor 34. In such a case, the vibration sensor 18 and the processing block 20 may be used during the manufacturing stage and are not (necessarily) provided in the end product version of the sound reproduction apparatus 30 which is made available to consumers or other end users.
  • the sensor 18 and the processing block 20 may be incorporated into the sound reproduction apparatus for use by the end user.
  • An example of such a sound reproduction apparatus is shown schematically in Figure 3 , in which the same reference numerals are used for the same or corresponding parts as in the example of Figure 2 and the description thereof is not repeated here.
  • the sound reproduction apparatus 30 additionally has a vibration sensor 18 and a processing block 20 as described herein.
  • the processing block 20 may be a separate processor or its function may be provided by the main processor 34 or the audio processor 12.
  • the vibration sensor 18 is fitted to the cabinet or casing 32 to detect vibrations of the cabinet or casing 32.
  • a vibration sensor 18 may be fitted to one or both loudspeaker cabinets instead of or in addition to a vibration sensor 18 fitted to the main cabinet or casing 32.
  • the sensor 18 and the processing block 20 may be used during a preliminary set-up of the sound reproduction apparatus when the sound reproduction apparatus is installed or deployed by the user so as to identify one or more resonant frequencies. Again, the data concerning the identified one or more resonant frequencies may be stored in the data storage 36 so as to be accessible later by the audio processor 12 during end use of the sound reproduction apparatus by the end user.
  • the sensor 18 and the processing block 20 may be used dynamically, in real time, when the sound reproduction apparatus 30 is being used by the end user.
  • the audio processor 12 processes the input audio signal 14 based at least in part on the identified one or more resonant frequencies and outputs the output audio signal 16.
  • the audio processor 12 operates to reduce the power at the resonant frequency, in particular the instantaneous power at the resonant frequency.
  • the objective here is to prevent resonance and therefore vibration of the sound reproduction apparatus occurring at the resonant frequency.
  • the audio processor 12 may only operate to reduce the power at the resonant frequency if the power was greater than some threshold.
  • the threshold may be preset, for example by the manufacturer who determines a suitable threshold for the specific sound reproduction apparatus through testing, and/or may be adjustable by the user so that the user can "fine-tune” this aspect of the operation of the audio processor 12.
  • the audio processor 12 may operate to reduce the power at the resonant frequency regardless of its power in the input audio signal 14.
  • the amount of reduction of the power at the resonant frequency may be by a fixed amount (corresponding for example to a certain number of decibels, say 1 or 2 decibels, or Watts of output power, say 3 to 5 mWatts) or a percentage or proportion of the power at the resonant frequency (of say 5% or 10% or so say).
  • the audio processor 12 processes the input audio signal 14 to increase the power of the input audio signal 14 at at least some other audio frequencies other than the resonant audio frequency.
  • the objective here is to "disguise" the reduction of the power at the resonant frequency, which makes the reduction of volume at the resonant frequency less noticeable for the user.
  • the reduction of the power at the resonant frequency and the increase of the power of the other frequencies is such that the total power (or, equivalently, the average power) of the output audio signal 16 is the same, or at least substantially the same, as the total (or average) power of the input audio signal 14 (to within 1% or within 5% or less say). Keeping the total (or average) power of the output audio signal 16 to be (at least approximately) the same as the original input audio signal 14 further helps to make the reduction at the resonant frequency less noticeable to the end user.
  • the other frequencies which are increased in power may be frequencies that are adjacent to or neighbouring to the resonant frequency.
  • the other frequencies which are increased in power may be frequencies that are within say 1 % or somewhere in the range of say 5% to 10% or so of the resonant frequency.
  • Figure 4 show plots of power against frequency of waveforms for audio signals.
  • the upper part of Figure 4 shows schematically an example of a waveform for an input audio signal 14.
  • the lower part of Figure 4 shows schematically an example of the waveform for the corresponding output audio signal 16 produced by processing the input audio signal 14.
  • the output of the processing block 20 shows that there is a large peak at a frequency f R having a power P R .
  • the power P R at this frequency f R is used as a trigger in this example for the audio processor 12 to reduce the power at that frequency f R because otherwise it is likely to cause a resonance and therefore vibration or buzzing.
  • this shows that the power of frequency f R has been reduced by the audio processor 12.
  • the power of the neighbouring frequencies that are adjacent to the resonant frequency f R is increased.
  • the neighbouring frequencies whose power are increased extend either side of the resonant frequency f R in this example.
  • the extent of the neighbouring frequencies whose power are increased is indicated schematically by vertical dashed lines in Figure 4 .
  • the neighbouring frequencies may extend out by say a percentage of the resonant frequency f R , such as ⁇ 1% or ⁇ 2% or so.
  • the resonant frequency f R may be say 500 Hz and the neighbouring frequencies may be 490 Hz to 510 Hz.
  • the neighbouring frequencies may extend out by a fixed number of Hz, such as 10 Hz or 20 Hz say.
  • the reduction of the power at the resonant frequency f R and the increase of the power of the other, neighbouring frequencies is such that the total (or average) power of the output audio signal 16 is the same, or at least substantially the same, as the total (or average) power of the input audio signal 14 (to within 5% or less say).
  • This may be regarded as increasing the bandwidth of the signal at the resonant frequency f R and decreasing its peak power so that the overall power is the same, or at least substantially the same.
  • the power of the neighbouring frequencies that are closest to the resonant frequency f R may be increased by a greater amount than the neighbouring frequencies that are further from the resonant frequency f R .
  • the increase in power may for example vary linearly with the distance of the neighbouring frequency from the resonant frequency f R .
  • Examples of the present disclosure help to prevent or eliminate vibration or buzzing that can occur in a sound reproduction apparatus, whilst at the same time reduce the likelihood that the user will notice that the audio signal has been treated to prevent vibration occurring.
  • processor or processing system or circuitry referred to herein may in practice be provided by a single chip or integrated circuit or plural chips or integrated circuits, optionally provided as a chipset, an application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), digital signal processor (DSP), graphics processing units (GPUs), etc.
  • the chip or chips may comprise circuitry (as well as possibly firmware) for embodying at least one or more of a data processor or processors, a digital signal processor or processors, baseband circuitry and radio frequency circuitry, which are configurable so as to operate in accordance with the exemplary embodiments.
  • the exemplary embodiments may be implemented at least in part by computer software stored in (non-transitory) memory and executable by the processor, or by hardware, or by a combination of tangibly stored software and hardware (and tangibly stored firmware).
  • a hard disk and non-volatile semiconductor memory e.g. a solid-state drive or SSD.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Circuit For Audible Band Transducer (AREA)
EP18192859.9A 2018-09-06 2018-09-06 Processeur audio et procédé de traitement d'un signal audio Pending EP3621314A1 (fr)

Priority Applications (1)

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EP18192859.9A EP3621314A1 (fr) 2018-09-06 2018-09-06 Processeur audio et procédé de traitement d'un signal audio

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP18192859.9A EP3621314A1 (fr) 2018-09-06 2018-09-06 Processeur audio et procédé de traitement d'un signal audio

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EP3621314A1 true EP3621314A1 (fr) 2020-03-11

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4831449A (en) * 1987-05-21 1989-05-16 Sony Corp. Television apparatus incorporating receiver and video tape recorder in a common cabinet
JP2005223385A (ja) * 2004-02-03 2005-08-18 Matsushita Electric Ind Co Ltd 電気音響再生装置
JP2008085647A (ja) * 2006-09-27 2008-04-10 Funai Electric Co Ltd スピーカシステム及びスピーカの音質調整方法

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4831449A (en) * 1987-05-21 1989-05-16 Sony Corp. Television apparatus incorporating receiver and video tape recorder in a common cabinet
JP2005223385A (ja) * 2004-02-03 2005-08-18 Matsushita Electric Ind Co Ltd 電気音響再生装置
JP2008085647A (ja) * 2006-09-27 2008-04-10 Funai Electric Co Ltd スピーカシステム及びスピーカの音質調整方法

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