EP0767570A2
Expired / Lapsed
EP
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Equalization of speech signal in mobile phone
Assignee: Nokia Oyj
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Filing: 1996-08-16
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Granted: —
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Expires: 2016-08-16
Abstract
Abstract The invention relates to equalization in a digital phone, advantageously a mobile phone. According to the invention, the equalization (4) of a reproduced sound is changed according to the operating conditions of the phone. Information about the conditions is obtained by monitoring the sound volume (19) set by the user, measuring the background noise (17) in the operating environment of the phone through the phone's microphone (9) and/or monitoring the quality (16) of the connection between the phone and the communication network. The low frequency emphasis is reduced in a very noisy environment and increased in a quiet environment. The telephone according to the invention is advantageously a mobile phone in a digital cellular network.
Inventors
- 👤 Ari Koski
- 👤 Janne Uitto
- 👤 Jari Sjöberg
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 16:17
CPC Classifications
H; H04; H04M; H04M1/00; H04M1/60; H04M1/6025; H04L; H04L1/00; H04L1/20
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
86 words
A method for improving the quality and intelligibility of sound reproduced by a telephone apparatus in which the reproduced sound is handled in a digital form and equalized (4) according to a certain frequency response, characterized in that there is generated control information describing the operating conditions (16; 17; 18; 19) of said telephone apparatus and the frequency response of said equalization (4) is changed on the basis of said control information to optimize the quality and intelligibility of the sound reproduced in a given situation.
Claim 2
Dependent Claim
61 words
The method of claim 1, characterized in that the proportional intensity of a certain frequency area is changed in said equalization, and said changing of the frequency response includes at least one of the following measures: changing of the gain of said frequency area, changing of the width of said frequency area, changing of the center frequency of said frequency area.
Claim 3
Dependent Claim
34 words
The method of claim 1 or 2, characterized in that said control information includes a first information element which is formed on the basis of the phone sound volume (19) set by the user.
Claim 4
Dependent Claim
53 words
The method of claim 3, characterized in that said first information element describes the gain of the low-frequency part of the sound reproduced, whereby the gain is increased when the user turns the phone sound volume (19) down and the gain is decreased when the user turns the phone sound volume (19) up.
Claim 5
Independent Claim
39 words
The method of any one of the preceding claims, characterized in that said control information includes a second information element which is formed on the basis of the noise (17) measured in the operating environment of said telephone apparatus.
Claim 6
Dependent Claim
63 words
The method of claim 5, characterized in that said second information element describes the gain of the low-frequency part of the sound reproduced, whereby the gain is increased when the measurement shows that the noise (17) in the operating environment is low, and the gain is decreased when the measurement shows that there is a lot of noise (17) in the operating environment.
Claim 7
Independent Claim
42 words
The method of any one of the preceding claims, characterized in that said control information includes a third information element which is formed on the basis of the quality (16) of the communication connection between said telephone apparatus and the communication network.
Claim 8
Dependent Claim
30 words
The method of claim 7, characterized in that said equalization is changed on the basis of said third information element to compensate for the low quality of the communication connection.
Claim 9
Dependent Claim
53 words
The method of claim 8, characterized in that said third information element describes the gain of the low-frequency part of the sound reproduced, whereby the gain is increased when the quality (16) of said communication connection is bad, and the gain is decreased when the quality (16) of said communication connection is good.
Claim 10
Independent Claim
250 words
The method of any one of the preceding claims, characterized in that it includes recurrently the following steps: a) without any special temporal order - the first information element is generated according to how the user adjusts the phone sound volume (19), - it is monitored when the user is not speaking during a call, and the noise (17) in the operating environment of the phone is measured during such moments and the second information element is formed on the basis of the noise measurement, - the quality (16) of the connection between the telephone and the communication networked used via it is monitored and the third information element is formed accordingly, and b) according to the information elements formed - the gain of the low-frequency part of the sound reproduced is changed inversely proportionally to the sound volume (19) set by the user, whereby value pairs representing a certain sound volume and the corresponding gain form a monotonely falling curve (A; B; C) in a system of coordinates where the gain is represented as a function of the sound volume setting, - said gain is scaled inversely proportionally to measured noise (17), whereby said curve shifts downwards (A->B; B->C) in said system of coordinates when the noise increases and upwards (C->B; B->A) when the noise decreases, and - if the connection between the communication network and the phone is bad, said gain of the low-frequency part is set constant, whereby it does not depend on the sound volume setting.
Claim 11
Independent Claim
33 words
The method of any one of the preceding claims, characterized in that said control information includes a fourth information element which is formed on the basis of auxiliaries (18) connected to said phone.
Claim 12
Dependent Claim
84 words
A telephone apparatus including a loudspeaker (8) for the reproduction of sound and a digital signal processing means (1) for the digital processing of the sound reproduced, which signal processing means includes an equalizer (4) which has a certain frequency response, characterized in that said telephone apparatus includes means (13; 15; 16; 17; 18; 19) for the generation of control information describing its operating conditions and a means (15) for changing the frequency response of said equalizer on the basis of said control information.
Claim 13
Dependent Claim
29 words
The telephone apparatus of claim 12, characterized in that it includes a control block (15) for collecting the data describing said operating conditions and for generating said control information.
Claim 14
Dependent Claim
51 words
The telephone apparatus of claim 13, characterized in that it includes a sound volume adjusting device (19) which can be used by the user and a means for conveying information about the sound volume set with said adjusting device to said control block (15) for the generation of said control information.
Claim 15
Dependent Claim
67 words
The telephone apparatus of claim 13 or 14, characterized in that it includes a microphone (9) for recording the sound to be transmitted via the telephone connection and noise measuring means (13; 13a, 13b, 13c) for measuring the noise recorded through said microphone and a means for conveying the data (17) representing the measured noise to said control block (15) for the generation of said control information.
Claim 16
Dependent Claim
66 words
The telephone apparatus of claim 15, characterized in that it includes a voice activity detection means (VAD) for determining whether or not the user is speaking on the phone during a call, and said noise measuring means (13; 13a, 13b, 13c) are arranged to measure noise only during those moments when the user is not speaking according to the information from said voice activity detection means.
Claim 17
Dependent Claim
31 words
The telephone apparatus of claim 15 or 16, characterized in that said noise measuring means (13; 13a, 13b, 13c) include a weighting filter (13b) which weights noise measurement at certain frequencies.
Claim 18
Dependent Claim
58 words
The telephone apparatus of any one of claims 13 to 17, characterized in that it includes a means for monitoring the quality (16) of the communication connection between it and the communication network and a means for conveying the information describing the quality of the connection to said control block (15) for the generation of said control information.
Claim 19
Dependent Claim
58 words
The telephone apparatus of any one of claims 12 to 18, characterized in that said equalizer (4) realizes the transfer function where the Zs represent delays of a time unit and said control information comprises variable parameters K, a1 and a2, of which K represents the gain and a1 and a2 represent the center frequency and the bandwidth.
Claim 20
Dependent Claim
26 words
The telephone apparatus of any one of claims 12 to 19, characterized in that it includes a digital signal processor (1) which includes said equalizer (4).
Claim 21
Dependent Claim
20 words
The telephone apparatus of claim 20, characterized in that said digital signal processor (1) also includes said control block (15).
Claim 22
Dependent Claim
26 words
The telephone apparatus of claim 20 or 21, characterized in that said digital signal processor (1) also includes said noise measuring means (13; 13a, 13b, 13c).
Claim 23
Dependent Claim
24 words
The telephone apparatus of any one of claims 12 to 22, characterized in that it is a mobile phone in a digital cellular network.
Claim 24
Dependent Claim
48 words
The telephone apparatus of any one of claims 12 to 23, characterized in that it includes a connecting means for the connection of auxiliaries and a means for conveying the information (18) describing the connected auxiliaries to said control block (15) for the generation of said control information.
Claim 25
Dependent Claim
14 words
The telephone apparatus of claim 24, characterized in that said auxiliaries include hands-free equipment.
References Cited (Backward Citations)
No citation records indexed.
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