Note: Descriptions are shown in the official language in which they were submitted.
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METHOD AND DEVICE FOR THE DETERMINATION OF RADIO
AND TELEVISION USERS BEHAVIOUR
The present invention belongs to the field of
broadcast audience research. It is particularly
referred to a method for the determination of the pro-
gram actually listened.
Background of the Invention
In the field of television audience research, a
number of different methods have become known for de-
termining the actually received and displayed program
and the identity of the viewers which follow the dis-
played program. The feature of identifying program
portions recorded on video recorders and displayed
later on has also been realized.
Although evident and in principle capable of be-
ing realized, such methods cannot be put into practice
in the field of radio broadcasting. One reason there-
for is that each television set is monitored which is
justified under the condition that each family owns a
small number of TV sets only (one or two, as a rule)
which have a fixed place. In this case, relatively
expensive monitoring devices may be provided which are
adapted to the actual set.
In contrast thereto, several radio sets are ex-
isting in most cases in a household which are some-
times also operated outdoors. Examples thereof are
car radios, walkmen and portable sets. Furthermore,
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radio is often passively listened in department stores,
supermarkets, restaurants, etc. In addition, the frequency
ranges of the radio programs are not the same all over a
country. Thus, in order to determine a program actually
listened from the tuning of a radio set, it would be
necessary to determine the actual place of listening, too,
and to determine the displayed program during evaluation
from a voluminous list of program transmission frequencies
which has continuously to be updated.
US-5 023 929 describes an appliance that is
used for recording hearing samples of a duration of
e.g. 3 seconds every 10 minutes. The ambient noise samples
are recorded on magnetic tape in an uncompressed state.
Thus, the apparatus must be carried by the participant in
the survey at all times, which amounts to a certain
complication on account of its size and weight and may be
awkward in the long run. Moreover, it is possible for the
participant to forget to carry the appliance, in which case
the survey will be incomplete.
EP-A-299 711 indicates a compression method for
digital audio data. The method allows a high-quality
restoration of an acoustic signal from the compressed data
stored in a semiconductor memory by decompression,
inter alia. However, the information content is not reduced
in this compression method. Therefore, it requires a
relatively large amount of memory, thereby again resulting
in a relatively voluminous construction if uninterrupted
operation of monitoring over several days is intended. It
will also be noted that the energy consumption increases
with the memory capacity.
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Thus, a monitoring of the radio reproduction and
the determination of the received radio program from the
tuning of the receiver, which is usually done with
television sets, is not practical with radio receivers.
There is an object of the present invention to
provide a method for the determination of the behavior of
persons watching a radio or television program which permits
the determination of the attended radio or television
program, independently of the whereabouts of the person.
Summarv of the Invention
This object is attained by a method which
comprises recording and storing acoustical hearing samples
from the environment of the listener, the hearing sample
recordings being made at predetermined times, and/or storing
of information identifying the recording time, together with
the hearing sample, the recorded signal being digitalized
and then stored in a non-volatile memory device being free
from mechani-
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cally movable parts which are important for the
storage; such memory devices are for example non-
volatile or battery buffered semiconductor memory
devices.
In the following, broadcast receiver shall be
construed as encompassing radios, TV sets and other
broadcast receiver devices bringing forth acoustically
recognizable sound by an attendant.
According to this method, hearing samples are re-
corded in the environment of a listener and then
stored in order to correlate them later on with the
corresponding recordings of one or more transmitted
programs. For this correlation, information about the
time is recorded too, or the hearing samples are re-
corded within a predetermined time frame whose start-
ing time is defined or, e.g., stored at the beginning
of the recording of the hearing samples. In order to
reduce the memory volume necessary for storing the
hearing samples, it is preferred to record and to
store only at predetermined times and each time only
during short time intervals.
The corresponding appliance, called monitor in
the following description, may be attached to a broad-
cast receiver, or it may be carried by the test per-
son. The first variant requires the determination of
who listens to the broadcast receiver and if the
broadcast receiver is listened at all, i.e. the
listener must be in sufficient proximity to the broad-
cast receiver. This may also be done by an input in
the monitor, e.g. through a keyboard, a coded card, or
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also by coded transmitters borne by the persons in the
test household.
The second variant, namely the monitor borne by
the test person, allows straight away to determine
what the carrier of the monitor listens at the moment.
A condition for this method is a small and lightweight
monitor which may for example be carried in a shirt
pocket. The monitor must function over a sufficiently
long time period. This requires on one hand a suffi-
ciently high memory capacity and, on the other hand,
the use of batteries as a power source since the
monitor is portable, optionally supported by solar
cells or other power sources accessible in mobile op-
eration. In order to use these energy sources as eco-
nomically as possible, the hearing samples are exclu-
sively stored in memory devices which do not contain
mechanically movable components, thus in particular no
magnetic tapes, etc.
The memory means to be used, such as non-volatile
or battery buffered semiconductor memories, have how-
ever a limited capacity only and are only able to
store digital data. Thus, appropriate methods for
storage in a form as compressed as possible and a
highliest possible reduction of data volume are neces-
sary. The recording of short hearing samples only,
interrupted by relatively long time intervals, already
reduces substantially the amount of data to be stored.
A further reduction may be obtained by limiting the
recording to a predetermined frequency band within the
region of audible frequencies, i. e. the audio band.
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After the analog to digital transformation, fur-
ther compression methods may be applied which may be
performed by a processor, namely in using the dif-
ferent data compressing methods known from the digital
techniques and generally applicable, as well as trans-
formations such as the (Fast) Fourier transformations.
The degree of data reduction can be controlled by the
density of the support sites.
A further aspect is the data and personality pro-
tection. It is foreseeable that test persons will not
like to carry about or even have in their neighborhood
an appliance which is able to record and to store any
spoken word, too. The method of the invention already
provides a protection as it stores short hearing peri-
ods only. The further processing steps already menti-
oned such as reduced monitored frequency band and the
application of transformations, further make the trac-
ing of a discussion more difficult. Finally, the data
may additionally be encoded prior to the storage, pre-
ferably by an irreversible process.
The determination of the program actually listen-
ed is made by comparing the hearing samples with the
simultaneously recorded program samples. Program
samples may be taken in the broadcast studio, at any
point of the transmitting installation or also in a
cable receiving installation where the channels are
definitely related to a particular program. This sam-
pling need not be made through an acoustic interface
but can be achieved in any other way whatsoever. It
is essential that the hearing samples are recorded
overlapping in time with the program samples, and that
the recorded data can be brought in such a form that
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they can be checked for correspondence by a correla-
tion process. The program samples may be immediately
submitted to the same procedures as the hearing
samples. Another possibility is to store the program
samples first as a raw version and to adapt them at
the moment of correlation to the hearing samples. By
this way, program samples can be correlated to stored
hearing samples which have been compressed, trans-
formed and/or coded in different ways.
A precondition is that the recording time of the
hearing samples and of the program samples can be
determined at the time of correlation. This is
achieved in the most simple way in storing the begin-
ning time of the recording together with the samples.
In a series of samples recorded one after the other,
it may be sufficient to store the real time and to
store afterwards only the time intervals between two
successive samples, or to calculate the recording
times of the further samples in supposing a sample
recording at regular time intervals.
The correlation of the hearing samples with the
program samples is made in a center. The transmission
of the hearing samples from the test households may be
effected in different manners. Due to the small
dimensions of the monitors, these may be sent directly
by mail to the center. It is possible to install a
device in the test households which is able to read
the memories of the monitors and which transmits the
data to the center by a modem. Optionally, a televi-
sion audience measurement system is already installed
in such a testing household. Such systems often al-
ready comprise a modem connected to a center for data
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transmission. Then, the data of the monitors can also be
transmitted to the center, e.g. by means of a special
adapter, over that measurement system.
The recording of the program samples can be
achieved by appliances similar to the monitors. Since these
appliances are stationary in most cases, a direct recording
of the program signal, i.e. without a detour through
acoustic reproduction, is applied, and storage is possible
during longer recording intervals since the program sampler
may comprise more complex memory means of higher capacities.
This allows the compensation of time shifts between hearing
samples and program samples during the subsequent
correlation procedure due to not exactly synchronous time
bases without shortening the effective correlation interval.
According to one aspect, the invention provides a
method for the identification of a hearing impression which
is perceived by a listener, the method comprising the
recording and storing of hearing samples taken from the
environment of the listener, the hearing sample recordings
being made at predetermined times or being stored together
with information about the recording time, the hearing
sample in the form of a recorded signal being digitized,
compressed to obtain a data rate of 100 Bytes/Min. at the
most, and then stored in a non-volatile memory device being
free from mechanically movable parts which are functionally
important for the storage, thereby allowing these steps of
the method to be performed by an appliance that is
discreetly carried by the listener.
According to another aspect, the invention
provides a device for carrying out a method in accordance
with those disclosed herewith, the device comprising: a
microphone, at least one component for the filtering out of
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a frequency band; an analog to digital converter; a
processing unit for the digitized data, the processing unit
applying at least one compression method to the digitized
data such that the digitized data are available at its
output at a rate of 100 Bytes/Min. at the most; and a non-
volatile memory for digitized, compressed data, the memory
free from mechanically movable components which are
important for the storing process; wherein the device
includes a timing unit for determining the time of the
hearing samples, and wherein the device is designed so small
and light that it may be discreetly carried by a person.
According to another aspect, the invention
provides an installation comprising a device in accordance
with those disclosed herewith, wherein the installation
comprises a second microphone, a transmitter being connected
to said second microphone, said second microphone for
wireless emission of the signal received by the second
microphone, the device further comprising a receiver for
this signal.
According to another aspect, the invention
provides a method for determining the behaviour of listeners
or viewers, comprising the following steps: collecting
hearing samples in accordance with methods thereof disclosed
herewith; generating and storing program samples from at
least one radio or television program, which overlaps in
time at least in part with said hearing samples, said
hearing samples and said program samples being subjected to
the same processing steps between recording and storing, and
correlating at a later time, temporally corresponding
hearing samples and program samples, a positive correlation
result indicating consistency between the program captured
by the hearing samples and that captured by the program
samples.
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Brief Description of the Drawings
The invention will now be explained further by
means of an exemplary embodiment thereof and with the aid of
the drawings wherein:
FIGURE 1 shows the function principle by means of
a circuit block diagram, and
FIGURE 2 shows a circuit block diagram in more
detail.
Detailed Description of the Invention
The audio signal coming from microphone 1 is
passed through the band pass 2 which filters a frequency
range of from 100 to 4000 sec-1, preferably from 300
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to 3000 sec-1, out of the whole audio frequency range.
The band width limited signal is passed to the analog
to digital converter 3 and then, in digital form, into
a first intermediate memory 4. The analog to digital
converter is controlled by a timer or clock 9. This
clock switches the analog to digital converter on dur-
ing one second at the beginning of every minute. The
clock 9 comprises a quartz time base which is syn-
chronized with a time base in the center.
The hearing sample stored in the memory 4 in
digital form during the recording time of one second
is read during the recording free remainder of the
minute and stored in memory 8 after Fourier trans-
formation in the Fourier transformer unit 5, compres-
sion in the compressor 6, and encoding in the encoding
unit 7.
Possible embodiments are for example the execu
tion as a credit card, a clip or also integrated into
a watch.
The monitors which are distributed in the test
household are put once a day into a charging and syn-
chronizing station which is existing once in the
household. The synchronizing station will synchronize
the clocks 9 in the individual monitors. It is also
able to read the memory 8 from each monitor and to
store the contents of the memory 8 in an own memory of
higher capacity which may also be a tape recorder.
The memory of the monitor is preferably erased there-
after. As a further function, the synchronizing sta-
tion may charge the rechargeable energy sources of the
monitor.
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The data transmission to the center may be ef-
fected in that, for example during the night, the
charging and synchronizing station is called up by the
center, or the station calls the center computer up,
whereupon it transmits the stored. data on request.
The clock existing in the charging and synchronizing
station may then be synchronized with the time base of
the center computer, too. The connection with the
center is built up either through an own modem or
through a modem of an already existing installation
for TV audience research. The second possibility con-
sists in sending the data carrier of the charging and
synchronizing station to the center. Finally, the
monitors themselves can be sent to the center, and the
clock incorporated into the monitors can then be syn-
chronized with the time base of the center.
The monitor can be adapted in different manners
to the prevailing conditions. In particular, the dif-
ferent processing procedures can be effected by only
one processor. When the recording time is only 1 sec-
ond per minute, it has 59 seconds to effect the trans-
formation, the compression and the encoding. The car-
rying out of all these operations by a processor addi-
tionally presents the advantage that a variation of
the overall function may be achieved by changing just
the program which controls the processor. For exam-
ple, the encoder or its code may be exchanged, the
compression can be switched on and off, and other
transformation techniques may be used.
The filter 2 may also be a digital one and will
then be positioned after the analog to digital con-
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verter. In the same manner, the filtering may be ef-
fected by a processor digitally. The sequence of the
functional elements may also be selected in another
manner.
The synchronizing of the time base 9 may be left
out when the time base 9 contains a receiver for a
standard time signal, e.g., DCF-77, which is also used
by the program samplers as a time standard.
A problem with the purely acoustical recording of
the hearing sample is a possibly too high ambient
noise level. A possible solution consists in attach-
ing so-called minispies to the loudspeakers which take
up the body sound of the loudspeaker and transmit it
directly to the monitors, for instance by means of
radio signals, infrared or ultrasound radiation. The
monitor may also be connected directly to the loud-
speaker or to the headphones output of e.g. a walkman.
A monitor may also be attached stationarily to a hi-fi
stereo set by means of an adapter that enables the
input of the listening persons. The monitor could
also be equipped with a button allowing its deactiva-
tion, for example during a confidential talk.
A preferred embodiment will now be described with
reference to FIG. 2. The monitor, namely the hearing
sampler carried by the listener, is integrated into a
watch, preferably a wrist watch. The microphone 1 has
a high to a very high sensitivity within the frequency
range of from about 200 s-1 to 3000 s-1 for the sound
waves 11, outside of this range only a low one. The
microphone acts thus as a preliminary filter. The
deviation 13 for the feeding in of signals instead of
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or additionally to the recording by the microphone 1
will be described later.
The signal 14 already limited as to band width
(about 200 to 3000 s-1) coming from the microphone is
fed to an amplifier and band pass 15 which raises the
signal to the level necessary for the following analog
to digital converter 3 and effects the band width
limitation with the desired sharpness. The output
signal 18 of the amplifier 15 is passed to the analog
to digital converter 3 which converts it into a
digitalized form 20. The conversion is effected with
a scanning rate of 6000 s-1 and a resolution of 8 bits
(= 1 byte) per scanned value. The transmission of the
output signal during the scan interval is effected by
the switch 22. Since the scanning interval is one
second, 6000 values (= 6000 byte) will be passed to
the intermediate memory 4. Switch 22 and analog to
digital converter 3 are controlled by the timer or
clock 9 which may be coupled to the time display of
the watch or works independently thereof, the clock 9
providing the scan rate signal 24 of 6000 s-1 to the
analog to digital converter 3 and the switch signal 25
to the switch 22 during a time period of 1 s in every
minute.
The data 29 are read out of the intermediate
memory 4 by the Fourier transformer unit 5. This
Fourier transformer unit works on time segments of 200
ms each of the one second hearing samples so that five
Fourier coefficient sets 30 are produced as a result
of each scanning interval which are stored in an in-
termediate memory 32.
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From this memory, the Fourier coefficients 34 are
fetched by the data compressor 6 and reduced in volume
by one of the current compression techniques such as
Huffmann encoding, Lempel-Ziv-Welch method, etc.
without information losses. Compressions up to 2/5th
of the input data amounts may be obtained or even more
if more powerful techniques will become known and
available. An experienced value is that about 100
byte of compressed data are produced per scanning in-
terval, i.e. per minute. The compressed Fourier
transformation data sets 37 are stored in a non-
volatile memory 8, e.g. a flash EPROM, having a capac-
ity of, e.g., 1 MB (= 220 byte). This capacity allows
at a data flux of 100 byte per minute an uninterrupted
wearing time of the watch of several days until the
readout of the memory. When the memory capacity will
further be increased by the development of the art,
this time period will be increased, too.
At least the Fourier transformer unit 5 and the
data compressor 6 are realized by a processor under
the control of corresponding programs. The processor
may take over, at the same time, the above mentioned
encoding, if necessary.
The reading of the data out of the EPROM 8 and
their deletion is effected in the charging and syn-
chronizing station 39 in which the watch containing
the monitor may be placed. The transmission of energy
and data is effected without contacts by an elec-
tromagnetic coupling, thus avoiding the opening of the
watch, and the charging and reading out requires only
little efforts of instruction of the operator and can
therefore made by the test person himself or herself.
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The monitor in the watch comprises, for the contact
with the charging station 39, the following functional
elements: reading control 40 and reset and erase con-
trol 41 for reading and erasing the memory 8; a clock
synchronisation unit 42 for synchronizing the monitor
claock 9, and a battery charging unit 43 which con-
tains the supply battery of the monitor and serves to
charge this battery. The data transmission is
preferably a serial one.
The synchronisation of the clock 9 is necessary
since the 200 ms partitions od the one second samples
must be able to be correlated exactly in time to the
samples taken in the broadcast station which may cause
problems even with a quartz time base in the course of
days. For the compensation of one of the most impor-
tant influence factors, the temperature, the tempera-
ture dependence of the clock 9 is determined and
stored for each monitor. By means of a temperature
sensor thermally coupled to the clock 9, especially to
its quartz, the time deviation caused by temperature
influences may be determined and corrected; a preci-
sion of ~ 200 ms time error per week can thus be ob-
tained.
Further possible additional devices are a per-
sonal identification unit 45, a "wearing" detector 46,
an attentiveness key 48 or similar for entering a
listening with particular attention, etc. The per-
sonal identification 45 is fixed as the user'code. It
will also be possible to provide several codes which
can be selected by means of actuating elements of the
watch.
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The "wearing" detector 46 serves for the auto-
matic detection whether the watch, i.e. the monitor,
is worn by the test person, and the hearing samples
correspond thus to the hearing impression of the
listener. As a secondary function, the acoustic su-
pervision may be turned off when the wach is not worn,
e.g. by night. The detector 46 may be constructed as
an inductive or a capacitive sensor which reacts, for
example, on the proximity to the body of the test per-
son or to the condition of the strap of the watch
(open or closed).
The attentiveness key 47 serves to allow the test
person to manually note phases of increased attention.
The comparative hearing samples which are re-
corded at the broadcast station, e.g. in the studio,
are treated and stored by a functionally identical
monitor. However, the signal is supplied not from the
microphone 1 but over the deviation 13 directly to the
input of the amplifier 15. The final storage is made
on a memory device having a high capacity, as usually
employed in the computer technique, e.g. on the base
of magnetic tapes. The functions necessary for the
portable and automatic operations such as the inter-
face units to the charging and synchronizing station,
the attentiveness key, the "wearing" sensor, etc., are
not provided in this case.
The invention can also be used for the determina-
tion of the user behaviour for other kinds of trans-
mission having an acoustic component such as televi-
sion or the like.
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