Equipment, method and use of the equipment in an audio system

Equipment, method and use of the equipment in an audio system
US 20100202624A1
(19) United States
(12) Patent Application Publication (10) Pub. No.: US 2010/0202624 A1
Makinen et al.
(54)
(43) Pub. Date:
EQUIPMENT, METHOD AND USE OF THE
EQUIPMENT IN AN AUDIO SYSTEM
(86)
PCT No.:
Aug. 12, 2010
PCT/FI2007/050159
§ 371 (0X1),
(75) Inventors:
Jari Makinen, lisalmi (Fl); Aki
Makivirta, Lapinlahti (Fl); Jussi
(2)’ (4) Date:
(30)
Mar‘ 27’ 2009
Foreign Application Priority Data
Tikkanen, lisalmi (Fl); Juha
Urhonens Iisalmi (F1)
Mar. 28, 2006
(F1) .................................... .. 20060296
Publication Classi?cation
Correspondence
Address:
.
Muncy, Gelssler, Olds.& Lowe, PLLC
(51)
4000 Legato Road, Suite 310
FAIRFAX VA 22033 (Us)
’
(73) Assignee:
(52)
GENELEC OY, Iisalmi (Fl)
(57)
Int. Cl.
H04R 1/08
(200601)
H04R 29/00
(2006.01)
US. Cl. ........................................... .. 381/59; 381/91
ABSTRACT
A method and means for a sound-reproduction system. The
(21)
APP1- NOJ
12/294,907
(22)
PCT Filed;
Mar, 23, 2007
means include a ?rst opening arrangement for a microphone,
and a second opening arrangement for a microphone stand,
formed in an essentially planar elastic material.
Patent Application Publication
Aug. 12, 2010 Sheet 1 0f 2
z?rfél'krgl??ln
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Fig. 1
(SST
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US 2010/0202624 A1
13
Patent Application Publication
Aug. 12, 2010 Sheet 2 0f 2
US 2010/0202624 A1
ig. 4
Aug. 12, 2010
US 2010/0202624 A1
EQUIPMENT, METHOD AND USE OF THE
EQUIPMENT IN AN AUDIO SYSTEM
BACKGROUND OF THE INVENTION
[0001]
1. Field of the Invention
[0002]
The present invention relates to a means for a sound
reproduction system.
[0003]
The invention also relates to a method in a sound
reproduction equipment.
[0004] 2. Brief Discussion of the RelatedArt
[0005] According to the prior art, calibration methods are
known, in Which a test signal is fed to a loudspeaker. The
response to the test signal is measured using a measuring
system and the frequency response of the system is adjusted
to be as even as possible using an equalizer.
[0006]
A drawback of the state of the art is that, in the
measuring system, the placing and ?rm installation of the
microphone requires a microphone-speci?c support, Which is
generally very expensive and microphone speci?c. In addi
tion, even in expensive microphones the microphone support
attenuates acoustic and mechanical vibrations poorly, Which
can signi?cantly interfere With electroacoustic measurement
and calibration.
[0007] The invention is intended to eliminate the defects of
the state of the art disclosed above and for this purpose create
an entirely neW type of means, method, and use in sound
reproduction equipment, especially in connection With its
calibration.
SUMMARY OF THE INVENTION
[0008] The invention is based on arranging for the attach
ment and support of the microphone an essentially planar
attachment piece, Which is equipped With tWo opening
arrangements and is formed from a relatively thick ?exible
material, for attaching the microphone to a stand.
[0009] According to a second preferred embodiment of the
invention, the attachment device is applied in an environment,
in Which the active loudspeaker is equipped With a signal
generator, Which can be used to create a logarithmically scan
forming an essentially sinusoidal electrical variable-fre
quency calibration signal, so that the calibration signal scans
at least essentially through the entire audio-frequency range.
[0015] Considerable advantages are gained With the aid of
the invention.
[001 6] With the aid of the means according to the invention,
it is possible to connect even a very loW-priced microphone to
a measuring system in a cost-effective manner. In particular,
the attachment means has a very great economical signi?
cance in connection With the measuring and calibration meth
ods described in the present application, because the highly
developed measuring and calibration method eliminates the
need for measurement microphones of a very high quality and
With a very high price.
[0017] According to the second preferred embodiment of
the invention, because the test signal is not fed from the
computer to the loudspeaker, but arises in the loudspeaker,
there are no other distortions or changes in the test signal
besides the acoustic response.
[0018] Besides the acoustic transfer path, the measuring
signal is affected only by the measuring microphone and the
frequency response of the input of the computer sound card.
[0019] Because the measuring signal is built in, it is alWays
available.
[0020]
Because the crest factor of the signal is small, it
produces a good signal-noise ratio.
[0021] According to the third embodiment of the invention,
the folloWing advantages are achieved.
[0022] As the distance of the microphone can vary greatly,
the magnitude of the acoustic response produced by the mea
suring signal can vary Within very Wide limits.
[0023] Noise produced by the environment does not vary in
the same Way, but instead remains (in each room) relatively
constant.
[0024] If the microphone is very close to the loudspeaker,
the signal being recorded may be too large, in Which case it
Will be peak-limited in the computer sound card.
[0025] If the microphone is very far aWay, the signal may be
too small relative to ambient noise, in Which case the signal
noise ratio Will remain poor.
ning sinusoidal test signal.
[0026]
[0010] According to a third preferred embodiment of the
invention, the attachment device is applied in an environment,
in Which the level of the measuring signal is adjusted in such
a Way as to achieve the greatest possible signal-noise ratio.
[0011] According to a fourth preferred embodiment of the
invention, the attachment device is applied in an environment,
in Which the phase of the main loudspeaker and the subWoofer
ensured With the aid of level setting.
[0027] Peak limiting of the measuring signal can be pre
An advantageous signal-noise ratio can alWays be
vented by reducing the level of the signal. The signal-noise
ratio can be improved by raising the level of the signal.
[0028] The setting of the level is knoWn to the controlling
computer all the time, and can be taken into account in cal
culations.
is set to be the same at the crossover frequency, With the aid of
[0029]
a sine generator built into the active subWoofer loudspeaker.
[0012] According to a ?fth preferred embodiment of the
invention, the attachment device is applied in an environment,
in Which a logarithmic sine signal is used to equalize the
of the fourth embodiment of the invention:
frequency responses of the loudspeakers at the listening posi
tioning (the location of the microphone), in order to eliminate
differences in the mutual levels and time-of-?ight delays of
the loudspeakers in the loudspeaker system.
[0013] More speci?cally, the means according to the inven
tion is characterized in that it comprises a ?rst opening
arrangement for a microphone, and a second opening
arrangement for a microphone stand, formed in a plate-like
elastic material of even thickness.
[0014] The method according to the invention is, in turn,
characterized in that the loudspeaker comprises means for
The folloWing advantages are achieved With the aid
[0030] The correct phase settings are found, irrespective of
Where the loudspeaker is placed (the distance affects the
sound level and the placing affects the phase).
[0031] The measurement corresponds to a real situation (in
Which the subWoofer and main loudspeaker operate simulta
neously and repeat the same audio signal).
[0032] According to the sixth preferred embodiment of the
invention, all the loudspeakers of the entire loudspeaker sys
tem are brought mutually to the correct level, to a virtual
distance, and With an identical room response.
[0033] Further scope of the applicability of the present
invention Will become apparent from the detailed description
given hereinafter. HoWever, it should be understood that the
detailed description and speci?c examples, While indicating
Aug. 12, 2010
US 2010/0202624 A1
preferred embodiments of the invention, are given by Way of
illustration only, since various changes and modi?cations
Within the spirit and scope of the invention Will become
apparent to those skilled in the art from this detailed descrip
tion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] The present invention Will become more fully
understood from the detailed description given hereinbeloW
and the accompanying draWings Which are given by Way of
illustration only.
[0035] FIG. 1 shoWs a block diagram of one system suitable
for the method according to the invention.
[0036] FIG. 2 shoWs a second calibration circuit according
to the invention.
[0037] FIG. 3 shoWs graphically the signal according to the
invention, Which the computer sound card records.
[0038] FIG. 4 shoWs graphically a typical measured signal
in the calibration arrangement according to the invention.
[0039] FIG. 5 shoWs graphically the test signal formed by
the loudspeaker.
[0040] FIG. 6 shoWs the attachment means according to the
invention.
[0041]
FIG. 7 shoWs the attachment means of FIG. 6 con
nected to the microphone and to the microphone stand.
[0042]
[0043]
[0044]
[0045]
[0046]
[0047]
In the invention, the folloWing terminology is used:
1 loudspeaker
2 loudspeaker control unit
3 acoustic signal
4 microphone
5 preampli?er
[0048]
[0049]
6 analog summer
7 sound card
[0050]
8 computer
[0051] 9 measuring signal
[0052]
[0053]
[0054]
[0055]
[0056]
10 test signal
11 USB link
12 control-netWork controller
13 control netWork
14 IO line
[0070] FIG. 2 shoWs the apparatus totality of the invention,
in Which the loudspeaker 1 produces an acoustic signal 3. For
test purposes an acoustic signal 3 is created from an electrical
calibration signal formed by the generator 15 of the control
unit 2 of the loudspeaker itself. The control unit 2 typically
contains an ampli?er thus making the loudspeaker (1) an
active loudspeaker. The test signal is preferably a sinusoidal
scanning signal, such as is shoWn graphically, among others,
in FIG. 6. The frequency of the calibration signal 50 (FIG. 5)
is scanned over the range of human hearing, preferably in
such a Way that this starts from the loWest frequencies and the
frequency is increased at a logarithmic speed toWards the
higher frequencies. The generating 50 of the calibration sig
nal is started by a signal brought to the control unit 2 of the
loudspeaker 1 over the control bus 13. The acoustic signal 3 is
received by the microphone 4 and ampli?ed by a preampli?er
5. In the analog summer 6, the signal coming from the pream
pli?er 5 is combined With the test signal 10, Which is typically
a square Wave. The analog summer 6 is typically a circuit
implemented using an operation ampli?er. The test signal 10
is obtained from the control unit 12 of the control netWork. In
practice, the test signal can be obtained directly from the IO
line 14 of the microprocessor of the control unit of the control
netWork.
[0071] Thus, according to the invention the acoustic mea
suring signal 3 can be initiated by remote control through the
control bus 13. The microphone 4 receives the acoustic signal
3, With Which the test signal 10 is summed The sound card 7
of the computer 8 receives a sound signal, in Which there is
initially the test signal and then after a speci?c time (the
acoustic time-of-?ight) the response 9 of the acoustic signal,
according to FIG. 2.
[0072] FIG. 3 shoWs the signal produced in the computer’s
sound card 7 by the method described above. The time t 1 is a
randomly varying time caused by the operating system of the
computer. The time t2 to the start of the acoustic response 9 is
mainly determined on the basis of the acoustic delay (time of
travel), and random variation does not appear in it. The acous
tic response 9 is the response of the loudspeaker-room system
[0057] 15 signal generator
[0058] 16 loudspeaker element
to the logarithmic sinusoidal scanning, the frequency of
Which is increasing.
[0073] According to the second preferred embodiment of
[0059]
18 interface device
the invention, a generator 15, Which produces a calibration
[0060]
[0061]
50 calibration signal
100 microphone holder
[0062] 101 microphone opening
[0063]
[0064]
[0065]
[0066]
102 stand opening
103 groove for microphone lead
104 microphone lead
105 microphone stand
DETAILED DESCRIPTION OF THE PREFERRED
EMBODIMENTS
[0067]
FIG. 1 shoWs the apparatus totality, in Which loud
speakers 1 are connected to a computer 8 through a control
netWork 13, by means of an interface device 18.
[0068] The interface device 18 contains a control-netWork
controller 12 according to FIG. 2, a preampli?er 5 and an
analog summer 6, to Which an IO line 15 coming from the
signal 50 that is precisely knoWn beforehand, is built into the
loudspeaker 1.
[0074] The calibration signal produced by the generator 15
is sine-scanning, the speed of Which frequency scanning
increases in such a Way that the logarithm of the frequency at
the moment is proportional to the time, log(f):k t, in Which f
is the momentary frequency of the signal, k is a constant
de?ning speed, and t is time. The increase in frequency accel
erates as time passes.
[0075] Because the test signal is precisely de?ned math
ematically, it can be reproduced in the computer accurately,
irrespective of the test signal produced by the loudspeaker 1.
[0076] Such a measuring signal contains all the frequencies
and the crest factor (the relation of the peak level to the RMS
level) of the signal is very advantageous in that the peak level
control-netWork controller, through Which IO line a test sig
is very close to the RMS level, and thus the signal produces a
very good signal-noise ratio in the measurement.
[0077] As the signal 50 (FIG. 5) starts moving from the loW
nal 10 is transmitted to the summer, is connected.
[0069] FIG. 2 contains the same functions as FIG. 1, but
advantageously in rooms With a reverberation time that is
only one loudspeaker 1 is shoWn, for reasons of clarity.
usually longer at loW frequencies than at high frequencies.
frequencies and its frequency increases, the signal operates
Aug. 12, 2010
US 2010/0202624 A1
[0078] The generation of the calibration signal 50 can be
initiated using a command given through remote control.
[0079] According to the fourth preferred embodiment of
the invention, the magnitude of the calibration signal 50 pro
duced in the loudspeaker can be altered through the control
[0097] A level is set for each loudspeaker, at Which the
loudspeakers appear to produce the same sound level at the
measuring point. The level of each loudspeaker can be mea
sured from the frequency response, either at a point fre
netWork 13.
the Wider frequency range can be calculated using the mean
[0080]
value, RMS value, or median. In addition, different Weighting
The calibration signal 50 is recorded. The magni
tude of the acoustic response 9 of the calibration signal 50
relative to the calibration signal is measured. If the acoustic
response 9 is too small, the level of its calibration signal 50 is
increased. If the acoustic response 9 is peak limited, the level
of the calibration signal 50 is reduced.
[0081]
The measurement is repeated, until the optimal sig
nal-noise ratio and level of the acoustic signal 9 have been
found.
[0082]
Level setting can be performed for each loudspeaker
quency, or in a Wider frequency range and the mean level in
factors can be given to the sound level at different frequen
cies, before the calculation of the mean level. The frequency
range and the Weighting factors can be selected in such a Way
that the sound level calculated in this Way from the different
loudspeakers and subWoofers is subjectively as similar as
possible. In a preferred implementation, the mean level is
calculated from the frequency band 500 Hz- 1 0 kHZ, using the
RMS value and in such a Way that all the frequencies have the
same Weighting factor.
separately.
[0098]
[0083]
described above.
Because the extent to Which the level has been
The subWoofer(s) phase is then adjusted as
altered is controlled by the computer 8 and thus knoWn, this
[0099]
information can be taken into account When calculating the
results, so that a reliable measurement result, Which is scaled
100 is essentially planar and is formed from an elastic mate
rial such as rubber or an elastic plastic. The holder is prefer
ably formed from a plate-like material of even thickness, for
correctly relative to the level, Will be obtained irrespective of
According to FIGS. 6 and 7, the microphone holder
the distance.
example, by laser cutting, or impact cutting With the aid of a
[0084]
die. Both a microphone opening 101 and an opening for the
stand 105 are formed in the holder 100. The openings 101 and
102 can be given a conical shape, in order to adapt the holder
According to the fourth preferred embodiment of
the invention, a built-in sine generator is used in the sub
Woofer. The phase of the subWoofer is adjusted through the
control-netWork 13 from the computer and the acoustic signal
is measured by means of the microphone.
[0085] Setting the subWoofer and the main loudspeaker to
the same phase at the crossover frequency takes place in tWo
stages.
[0086]
Stage 1: the levels of the subWoofer and the ref
erence loudspeaker are set to be the same by measuring
one or both levels separately and setting the level pro
duced by each loudspeaker.
[0087] Stage 2: both loudspeakers repeat the same sine
signal, Which the subWoofer generates.
[0088] The common sound level is measured by the micro
phone.
[0089]
The phase is adjusted and the phase setting at Which
the sound level is at a minimum is sought. The loudspeaker
and subWoofer are then in an opposing phase.
[0090] The subWoofer is altered to a phase setting that is at
180 degrees to this, so that the loudspeaker and the subWoofer
are in the same phase and thus the correct phase setting has
been found.
[0091] According to the ?fth preferred embodiment of the
invention, the acoustic impulse response of all the loudspeak
ers 1 of the system is measured using the method described
above. Such a calibration arrangement is shoWn in FIG. 3.
[0092]
The frequency response is calculated from each
impulse response.
[0093] The distance of the loudspeaker is calculated from
each impulse response.
[0094] On the basis of the frequency response, settings of
the equaliZer ?lter that Will achieve the desired frequency
response in the room (even frequency response) are planned.
[0095] The (relative) sound level produced by the equaliZed
response is calculated.
to as many different kinds of stand 105 and microphone 4 as
possible. In addition, the microphone holder 100 can be
equipped With a groove 103 formed in its outer surface, for the
microphone lead. The groove 103 is intended to reduce the
mechanical loading of the microphone lead 104 on the con
tact point of the microphone 4.
[0100] The opening shapes shoWn in the ?gures can of
course be different. Thus both triangular and other polygonal
shapes are, Within the scope of the inventive idea, possible
manners of attachment for both the microphone and the stand.
Opening arrangements equipped With incisions can also be
accommodated Within the scope of the inventive idea.
[0101]
In the present application the term audio frequency
range refers to the frequency range 10 HZ-20 kHZ.
[0102] In a preferred implementation, the stages described
above are performed in the folloWing order:
[0103] the acoustic responses of all the loudspeakers are
recorded With the aid of the computer sound card,
[0104] the impulse response of the loudspeaker is calcu
lated from each of the responses,
[0105] the time of travel of the sound is measured from
each impulse response and the distance of the loud
speaker is calculated on its basis,
[0106] on the basis of the distance of each loudspeaker,
the additional delay that makes the time of travel of the
sound coming from the loudspeaker the same as that of
the time of travel of the other loudspeakers is calculated,
[0107] the frequency response is calculated from each
impulse response,
[0108] on the basis of the frequency responses, the levels
of the loudspeakers are calculated,
[0109] a correction is calculated for each loudspeaker,
Which Will make its level the same as that of the other
loudspeakers.
[0096] A delay is set for each loudspeaker, by means of
Which the measured response of all the loudspeakers contains
the same amount of delay (the loudspeakers Will appear to be
ous that the same may be varied in many Ways. Such varia
tions are not to be regarded as a departure from the spirit and
equally distant).
scope of the invention, and all such modi?cations as Would be
[0110]
The invention being thus described, it Will be obvi
Aug. 12, 2010
US 2010/0202624 A1
obvious to one skilled in the art are intended to be included
tion signal, so that the calibration signal scans at least
Within the scope of the following claims.
1. A means for a sound-reproduction system, comprising:
a ?rst opening arrangement for a microphone, and
a second opening arrangement for a microphone stand,
6. A method for supporting and attaching a microphone in
a sound-reproduction system, Wherein the microphone is
formed in a plate-like elastic material of even thickness.
2. The means according to claim 1, further comprising a
groove arrangement for a microphone lead.
3. The means according to claim 1, Wherein at least one of
essentially through the entire audio-frequency range.
attached to a microphone stand With the aid of a uni?ed,
planar, elastic attachment means, in such a Way that the
microphone is attached With the aid of a ?rst opening arrange
ment to the attachment means and the attachment means is,
for its part, attached to the microphone stand With the aid of a
the opening arrangements has a circular shape.
second opening arrangement.
4. The means according to claim 1, Wherein the cross
section of at least one of the opening arrangements is conical.
5. The means according to claim 1 for a sound-reproduc
7. The method according to claim 6, Wherein the micro
phone lead is supported in a groove arrangement.
tion system, Which comprises a loudspeaker, control appara
tus for the loudspeaker, signal and control connections to the
loudspeaker, a microphone for measuring the response of the
the opening arrangements is formed With a circular shape.
loudspeaker, and analysis and control apparatuses for analys
ing and setting the signal obtained from the microphone, on
the basis of the analysis results, Wherein:
8. The method according to claim 6, Wherein at least one of
9. The method according to claim 6, Wherein at least one of
the opening arrangements is formed With a conical cross
section.
10. Use of a plate-like elastic material of even thickness
equipped With tWo holes as a microphone holder.
the loudspeaker comprises means for forming an essen
tially sinusoidal electrical variable-frequency calibra
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