EP0844805A1 - Amplificateur à compression du signal - Google Patents
Amplificateur à compression du signal Download PDFInfo
- Publication number
- EP0844805A1 EP0844805A1 EP96650053A EP96650053A EP0844805A1 EP 0844805 A1 EP0844805 A1 EP 0844805A1 EP 96650053 A EP96650053 A EP 96650053A EP 96650053 A EP96650053 A EP 96650053A EP 0844805 A1 EP0844805 A1 EP 0844805A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- output
- amplifier
- gain
- signal
- compression
- 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.)
- Withdrawn
Links
- 230000006835 compression Effects 0.000 title claims abstract description 109
- 238000007906 compression Methods 0.000 title claims abstract description 109
- 238000000034 method Methods 0.000 abstract description 4
- 230000006870 function Effects 0.000 description 15
- 239000003990 capacitor Substances 0.000 description 10
- 230000009467 reduction Effects 0.000 description 7
- 230000008878 coupling Effects 0.000 description 6
- 238000010168 coupling process Methods 0.000 description 6
- 238000005859 coupling reaction Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 6
- 108010074506 Transfer Factor Proteins 0.000 description 5
- 230000003321 amplification Effects 0.000 description 5
- 230000008859 change Effects 0.000 description 5
- 238000003199 nucleic acid amplification method Methods 0.000 description 5
- 238000009738 saturating Methods 0.000 description 5
- 230000002829 reductive effect Effects 0.000 description 4
- 239000004065 semiconductor Substances 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 3
- 230000001419 dependent effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000002238 attenuated effect Effects 0.000 description 2
- 230000000670 limiting effect Effects 0.000 description 2
- 230000000873 masking effect Effects 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000000593 degrading effect Effects 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000002123 temporal effect Effects 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R25/00—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception
- H04R25/35—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception using translation techniques
- H04R25/356—Amplitude, e.g. amplitude shift or compression
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R25/00—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception
- H04R25/50—Customised settings for obtaining desired overall acoustical characteristics
- H04R25/502—Customised settings for obtaining desired overall acoustical characteristics using analog signal processing
Definitions
- Distortion in the hearing aid art is defined as the generation of added undesired sounds in the output signal that are not present in the input signal. It is believed that such distortion, that is, these additional sounds, act as a type of masking noise for speech, both by direct masking of low-level speech cues that fill in the temporal structure of speech sounds and by degrading important amplitude cues. Peak-clipping has been used as a technique for limiting the amplitude of the output stage of a standard hearing aid, however, the peak-clipping technique often creates distortions in the output stage of the hearing aid circuitry.
- a similar overload effect may also occur when using class D amplifiers in the output stage, though the saturation mechanism is different.
- the output stage 34 operates by producing a variable pulse-width modulated signal across the transducer 50, for example, the speaker coil. As either the input sound level or the amount of system amplification is increased, the pulses eventually merge into each other and the output signal reaches saturation, thus causing distortion, for example, in the form of peakclipping.
- distortion begins at about 3 dB below maximum acoustic output.
- Fig. 2 The high-distortion effects of saturation can be seen graphically in Fig. 2 for a typical class D peak-clipping hearing aid used in the hearing aid circuit of Fig. 1.
- the peak acoustic gain of this hearing aid was 35 dB
- the peak saturated sound pressure level (SSPL) was 107 dB
- the frequency response matrix slope i.e., the difference in acoustic gain between peak and 500 Hz.
- Fig. 2 a plot of the harmonic distortion versus frequency for input sound levels of 60, 70, 80 and 90 dB is provided. These input sound levels correspond to soft speech, conversational speech, loud speech, and shouted speech, respectively.
- Fig. 3 is a graphical representation of an example of two possible non-linear compression functions compared to a linear compression function for a compression amplifier with a compression ratio of 2 to 1. The graph illustrates a 10 dB change in the input acoustic sound pressure level over a range of between 60 dB and 90 dB.
- the change in the output acoustic sound pressure level should be 5 dB for every 10 dB change in input acoustic sound pressure level.
- the conventional compression amplifier has a non-linear compression function over the dynamic range of the amplifier.
- the compression function is linear between 60 dB and 80 dB and the output sound pressure level change is compressed by 5 dB for every 10 dB change in the input sound level.
- the compression function becomes non-linear and the output acoustic sound pressure level is compressed by, for example, 4 dB or 6 dB.
- the gain control circuit has an input coupled to the amplifier output and an output coupled to the gain controller.
- the gain control circuit is configured to compare an output voltage on the amplifier output with a predetermined threshold voltage and to generate the gain control signal on the gain control circuit output.
- this signal when activated, provides continuous gain adjustment of the amplifier when the amplifier output voltage is greater than the threshold voltage.
- the gain control circuit provides means, such as a relay, for selectively controlling the gain control signal so that when the amplifier output exceeds the threshold signal level the gain control signal is generated.
- the predetermined threshold voltage is set to a value below a voltage where the amplifier saturates.
- the gain control circuit preferably includes a rectifier circuit portion having an input coupled to the output of the amplifier and an output.
- the output of the rectifier circuit portion is a DC voltage.
- a voltage comparing circuit portion is provided to receive the rectified voltage and the predetermined threshold voltage and to generate an output voltage which is the difference between the rectified voltage and the threshold voltage.
- a summing circuit portion has a first input coupled to the output of the voltage comparing circuit portion and a second input coupled to a sub-threshold amplifier. The summing circuit portion generates an output signal that is the sum of the voltages on the first and second inputs.
- the gain control circuit also includes a current generating circuit portion having an input coupled to the output of the summing circuit and an output coupled to the gain controller. The current generating circuit generates the required control current to adjust the gain of the amplifier. The control current is proportional to the rectified voltage and the threshold voltage.
- the present invention also provides a hearing aid that utilizes the compression amplifier of the present invention to improve the sound quality heard by a user.
- the hearing aid includes a preamplifier network having an input connected to a sound detector and an output connected to an output drive network.
- the output drive network has an input connected to the output of the preamplifier network and an output connected to a sound transducer.
- the preamplifier network includes the compression amplifier of the present invention.
- the preamplifier network has an amplifier with input and output legs, a gain controller coupled between the input leg and output leg of the amplifier, and a gain control circuit connected to the amplifier and the gain controller.
- the gain controller is responsive to a gain control signal generated by the gain control circuit so as to permit continuous gain adjustment of the amplifier.
- the output drive network also includes the above-described compression amplifier of the present invention.
- the output drive network has an amplifier, a gain controller, and a gain control circuit which operate to automatically adjust the gain of the amplifier to provide a quality sound to be emitted by the sound transducer.
- the hearing aid also includes a volume control circuit connected between the output of the preamplifier network and the input of the output drive network which permits the user to attenuate the volume of the sound emitted from the sound transducer.
- a volume control circuit is a variable resistor connected in a voltage divider configuration between the output of the preamplifier network and the input of the output drive network.
- the hearing aid according to the present invention includes a preamplifier network and an output drive network wherein the preamplifier network uses the compression amplifier and the output drive network has a fixed gain.
- the hearing aid includes a preamplifier network and an output drive network wherein the preamplifier network has a fixed gain and the output drive network has a fixed gain and the output drive network use the compression amplifier of the present invention.
- Compression parameters of the compression amplifier according to the present invention are dependent upon certain mathematical representations defined herein.
- the compression amplifier according to the present invention provides two basis modes of operation. The first mode is identified as a "below threshold mode" and the second mode is identified as an "above threshold mode". In the below threshold mode, the compression amplifier provides a fixed gain independent Of the input acoustic sound pressure level. In the above threshold mode, the compression amplifier provides a variable gain that is dependent upon the input acoustic sound pressure level, the desired compression ratio and the gain transfer compression threshold factor of the compression amplifier.
- the compression amplifier 60 includes an amplifier 62, preferably an operational amplifier, a gain controller 64, a rectifier and peak detector circuit 70, and a gain control circuit 66 responsive to the rectified output of the amplifier so as to control the gain controller 64.
- the gain controller may be a variable resistor or other equivalent devices which are capable of controlling the gain of the amplifier 62.
- the gain controller 64 is a current-controlled variable resistor that has a small signal resistance that is inversely proportional to the DC current flowing through the gain control circuit.
- the gain of the operational amplifier 62 is controlled by fixed resistor 68 having a value R and the gain controller 64. As seen in Fig.
- the gain control circuit 66 is connected in the feedback path of the operational amplifier 62.
- the desired compression function can be realized by modulating the current flowing through the fixed resistor 68, such that as the current increases the gain of the amplifier 60 decreases, and as the current decreases the gain increases.
- the compression amplifier continues to operate as such until the compression amplifier is operating in the below threshold mode where the gain is fixed.
- the gain control current (I cm ) required for a certain compression ratio is the ratio of the rectified compression amplifier output voltage
- GR 20log 10 R st R - 20log 10 R cm
- GR 20 log 10 R st R - log 10 R cm
- GR 20[log 10 [ R st ] - log 10 [ R cm ]]
- GR 20log 10 R st R cm where R is the value of resistor 68.
- equation 12 provides that the gain control current (I cm ) required for a certain compression ratio is the ratio of the rectified compression amplifier output voltage
- the preamplifier stage gain control circuit 66 senses or measures the voltage of the output signal of the amplifier 62. If the voltage of the amplifier output signal exceeds the predefined threshold voltage the gain of the amplifier 62 is automatically decreased by adjusting the resistance of variable resistor 64.
- the predefined threshold voltage is 7.8 mV (rms) input-referred which typically corresponds to an 85 dB sound pressure level acoustic input with a battery voltage of 1.25 volts.
- the resistance of the variable resistor 64 is adjusted so that the amplifier continues to operate in the linear region and thus inhibits the amplifier 62 from saturating.
- the gain control circuit 66, the resistor 68, the variable resistor 64, and the amplifier 62 form an output stage compression amplifier 60, that controls the gain of the amplifier 62.
- the output stage compression amplifier is provided to reduce the gain of the output stage just before the output signal of the amplifier 62 exceeds the capabilities of the supply voltage, that is, prior to amplifier saturation. Utilization of the gain control circuit 66 causes the output stage amplifier 62 to amplify within its linear region and thus prevents the amplifier from saturating. Hence, saturation distortion, for example, peak-clipping is limited or substantially minimized even when the input sound level exceeds 85 dB.
Landscapes
- Health & Medical Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Neurosurgery (AREA)
- Otolaryngology (AREA)
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Tone Control, Compression And Expansion, Limiting Amplitude (AREA)
- Control Of Amplification And Gain Control (AREA)
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002190787A CA2190787C (fr) | 1996-11-20 | 1996-11-20 | Un amplificateur a compression de gain dote d'une fonction de compression lineaire |
| EP96650053A EP0844805A1 (fr) | 1996-11-20 | 1996-11-25 | Amplificateur à compression du signal |
| AU74031/96A AU7403196A (en) | 1996-11-20 | 1996-11-27 | A gain compression amplifier providing a linear compression function |
| JP8351602A JPH10200352A (ja) | 1996-11-20 | 1996-12-27 | 利得圧縮増幅器及び補聴器 |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002190787A CA2190787C (fr) | 1996-11-20 | 1996-11-20 | Un amplificateur a compression de gain dote d'une fonction de compression lineaire |
| EP96650053A EP0844805A1 (fr) | 1996-11-20 | 1996-11-25 | Amplificateur à compression du signal |
| AU74031/96A AU7403196A (en) | 1996-11-20 | 1996-11-27 | A gain compression amplifier providing a linear compression function |
| JP8351602A JPH10200352A (ja) | 1996-11-20 | 1996-12-27 | 利得圧縮増幅器及び補聴器 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP0844805A1 true EP0844805A1 (fr) | 1998-05-27 |
Family
ID=27423807
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP96650053A Withdrawn EP0844805A1 (fr) | 1996-11-20 | 1996-11-25 | Amplificateur à compression du signal |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0844805A1 (fr) |
| JP (1) | JPH10200352A (fr) |
| AU (1) | AU7403196A (fr) |
| CA (1) | CA2190787C (fr) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6549755B2 (en) * | 2001-05-04 | 2003-04-15 | Glowlink Communications Technology, Inc. | Method and apparatus for monitoring and controlling gain compression in a transmitted signal |
| US7120392B2 (en) | 2002-10-11 | 2006-10-10 | Glowlink Communications Technology, Inc. | Uplink power control using loopback communications carriers |
| US7639761B2 (en) | 2002-03-04 | 2009-12-29 | Glowlink Communications Technology, Inc. | Detecting and measuring interference contained within a digital carrier |
| US8031893B2 (en) | 2006-08-11 | 2011-10-04 | Panasonic Electric Works Co., Ltd. | Hearing aid |
| CN102739178A (zh) * | 2011-04-15 | 2012-10-17 | 快捷半导体(苏州)有限公司 | 混频信号动态范围压缩装置及相关方法 |
| WO2013057718A1 (fr) * | 2011-10-19 | 2013-04-25 | Cochlear Limited | Règle de prescription acoustique basée sur une plage dynamique mesurée in situ |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006162463A (ja) * | 2004-12-08 | 2006-06-22 | Takenaka Engineering Co Ltd | 人体検知器 |
| DE102006046403A1 (de) * | 2006-09-29 | 2008-04-03 | Robert Bosch Gmbh | Schaltungsanordnung für ein mikromechanisches Sensorelement mit einer Kondensatoranordnung |
| JP5510559B2 (ja) * | 2010-12-20 | 2014-06-04 | 株式会社ニコン | 音声制御装置および撮像装置 |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0087893A1 (fr) * | 1982-02-19 | 1983-09-07 | Linear Technology Inc. | Détecteur de valeur de pointe |
| US5128566A (en) * | 1989-11-03 | 1992-07-07 | Etymotic Research, Inc. | Variable attenuator circuit |
-
1996
- 1996-11-20 CA CA002190787A patent/CA2190787C/fr not_active Expired - Fee Related
- 1996-11-25 EP EP96650053A patent/EP0844805A1/fr not_active Withdrawn
- 1996-11-27 AU AU74031/96A patent/AU7403196A/en not_active Abandoned
- 1996-12-27 JP JP8351602A patent/JPH10200352A/ja not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0087893A1 (fr) * | 1982-02-19 | 1983-09-07 | Linear Technology Inc. | Détecteur de valeur de pointe |
| US5128566A (en) * | 1989-11-03 | 1992-07-07 | Etymotic Research, Inc. | Variable attenuator circuit |
Non-Patent Citations (2)
| Title |
|---|
| CLANCY D A: "HIGHLIGHTING DEVELOPMENTS IN HEARING AIDS", HEARING INSTRUMENTS, vol. 46, no. 12, December 1995 (1995-12-01), pages 18, 20, XP000628032 * |
| SERDIJN W A ET AL: "LOW-VOLTAGE LOW-POWER FULLY-INTEGRATABLE AUTOMATIC GAIN CONTROLS", INTERNATIONAL SYMPOSIUM ON CIRCUITS AND SYSTEMS. (ISCAS), LINEAR CIRCUITS AND SYSTEMS (LCS), ANALOG SIGNAL PROCESSING (ASP) LONDON, MAY 30 - JUNE 2, 1994, vol. 5, 30 May 1994 (1994-05-30), INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS, pages 505 - 508, XP000592893 * |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6549755B2 (en) * | 2001-05-04 | 2003-04-15 | Glowlink Communications Technology, Inc. | Method and apparatus for monitoring and controlling gain compression in a transmitted signal |
| US7639761B2 (en) | 2002-03-04 | 2009-12-29 | Glowlink Communications Technology, Inc. | Detecting and measuring interference contained within a digital carrier |
| US7120392B2 (en) | 2002-10-11 | 2006-10-10 | Glowlink Communications Technology, Inc. | Uplink power control using loopback communications carriers |
| US8031893B2 (en) | 2006-08-11 | 2011-10-04 | Panasonic Electric Works Co., Ltd. | Hearing aid |
| CN102739178A (zh) * | 2011-04-15 | 2012-10-17 | 快捷半导体(苏州)有限公司 | 混频信号动态范围压缩装置及相关方法 |
| WO2013057718A1 (fr) * | 2011-10-19 | 2013-04-25 | Cochlear Limited | Règle de prescription acoustique basée sur une plage dynamique mesurée in situ |
| US9301068B2 (en) | 2011-10-19 | 2016-03-29 | Cochlear Limited | Acoustic prescription rule based on an in situ measured dynamic range |
Also Published As
| Publication number | Publication date |
|---|---|
| CA2190787C (fr) | 2000-02-01 |
| AU7403196A (en) | 1998-06-04 |
| CA2190787A1 (fr) | 1998-05-20 |
| JPH10200352A (ja) | 1998-07-31 |
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| 17Q | First examination report despatched |
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| STAA | Information on the status of an ep patent application or granted ep patent |
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