Koninklijke Kpn N.v.

Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno

John Gerard Beerends

Andries Pieter Hekstra

Mattijs Oskar Van Deventer

Hans Maarten Stokking

Omar Aziz Niamut

Victor Bastiaan Klos

Fabian Arthur Walraven

Jeroen Van Vugt

Robert Koenen

Franciscus Elisabeth De Caluwe

Symon Ronald Appel

Marc Jan Christiaan Van Den Homberg

Niels Martinus Philippe Neumann

Ronald Alexander Van Buuren

The present document relates to a method of determining a perceptual impact of an amount of echo or reverberation in an degraded audio signal on a perceived quality thereof, wherein the degraded audio signal is received from an audio transmission system, wherein the degraded audio signal is obtained by conveying through said audio transmission system a reference audio signal such as to provide said degraded audio signal. The method includes performing a windowing operation on the degraded and reference audio signal by multiplying these with a window function to yield degraded and reference digital audio samples. Local estimates of an amount of echo or reverberation are determined on the basis of these samples.

Method of determining a perceptual impact of reverberation on a perceived quality of a signal, as well as computer program product

The present invention relates to a method of evaluating quality of a degraded speech signal received from an audio transmission system conveying a reference speech signal. The method comprises sampling said signals into reference and degraded signal frames, and forming frame pairs by associating reference and degraded signal frames with each other. For each frame pair a difference function representing disturbance is provided, which is then compensated for specific disturbance types for providing a disturbance density function. Based on the density function of a plurality of frame pairs, an overall quality parameter is determined. The method provides for compensating the overall quality parameter for the effect that the impact of noise in frequency bands where there is only marginal speech activity when compared to natural speech is not correctly modelled in the current measurement standards.

Method of and apparatus for evaluating quality of a degraded speech signal

The present invention relates to a method of evaluating intelligibility of a degraded speech signal received from an audio transmission system conveying a reference speech signal. The method comprises sampling said reference and degraded signals into reference and degraded signal frames, and forming frame pairs by associating reference and degraded signal frames with each other. For each frame pair a difference function representing disturbance is provided, which is then compensated for specific disturbance types for providing a disturbance density function. Based on the density function of a plurality of frame pairs, an overall quality parameter is determined. The method provides for weighing disturbances in silent periods dependent on the loudness of the reference signal.

Method of and apparatus for evaluating intelligibility of a degraded speech signal, through providing a difference function representing a difference between signal frames and an output signal indicative of a derived quality parameter

The present invention relates to a method of evaluating intelligibility of a degraded speech signal received from an audio transmission system conveying a reference signal. The method comprises sampling said reference and degraded signal into frames, and forming frame pairs. For each pair one or more difference functions representing a difference between the degraded and reference signal are provided. A difference function is selected and compensated for different disturbance types, such as to provide a disturbance density function adapted to human auditory perception. An overall quality parameter is determined indicative of the intelligibility of the degraded signal. The method comprises determining a switching parameter indicative of audio power level of said degraded signal, for performing said selecting.

Method of and apparatus for evaluating intelligibility of a degraded speech signal, through selecting a difference function for compensating for a disturbance type, and providing an output signal indicative of a derived quality parameter

A method of generating a stream comprising synchronized interactive content is described. The method comprises the steps of: transmitting a first stream from a studio to a terminal or a terminal system of a first user and to a buffer; transmitting in response to the first stream a second stream to a mixer connected to the buffer, the second stream comprising content generated in reaction to the content of the first stream; providing the mixer with a temporal relation between the packets in the first and second stream; generating a first output stream comprising a substantially synchronized content by mixing packets in second stream with packets of the buffered first stream on the basis of the temporal relation.

Generating a stream comprising synchronized content

The present invention relates to a method of evaluating intelligibility of a degraded speech signal received from an audio transmission system conveying a reference speech signal. The method comprises sampling said signals into reference and degraded signal frames, and forming frame pairs by associating reference and degraded signal frames with each other. For each frame pair a difference function representing disturbance is provided, which is then compensated for specific disturbance types for providing a disturbance density function. Based on the density function of a plurality of frame pairs, an overall quality parameter is determined. The method provides for compensating the overall quality parameter for the effect that the assessment of intelligibility of CVC words is dominated by the intelligibility of consonants.

Method of and apparatus for evaluating intelligibility of a degraded speech signal

The invention relates to a method for determining a quality indicator representing a perceived quality of an output signal of an audio device with respect to a reference signal. Such audio device may for example be a speech processing system. In the method the reference signal and the output signal are processed and compared. The processing includes dividing the reference signal and the output signal into mutually corresponding time frames. The processing further includes scaling the reference signal towards a fixed intensity level. Time frames of the output signal are selected based on measurements performed on the scaled reference signal. Then, a noise contrast parameter is calculated based on the selected time frames of the output signal. A noise suppression is applied on at least one of the reference signal and the output signal based on the noise contrast parameter. Finally, the reference signal and the output signal are perceptually subtracted to form a difference signal, and the quality indicator is derived from the difference signal.

Method and system for determining a perceived quality of an audio system

The invention relates to a method for determining a quality indicator representing a perceived quality of an output signal of an audio system with respect to a reference signal. The reference signal and the output signal are processed and compared. The processing includes dividing the reference signal and the output signal into mutually corresponding time frames, and includes scaling the intensity of the reference signal towards a fixed intensity level, and then performing measurements on time frames within the scaled reference signal for determining reference signal time frame characteristics. Further on, the loudness of the output signal is scaled towards a fixed loudness level in the perceptual loudness domain. Finally, the loudness of the reference signal is scaled from a loudness level corresponding to the output signal related intensity level towards a loudness level related to the loudness level of the scaled output signal in the perceptual loudness domain.

The invention provides a softscaled frequency compensation function that allows the evaluation of a first quality measure indicating a global impact of all distortions in an audio transmission system, including linear frequency response distortions and second quality measure that only lakes into account the impact of linear frequency response distortions. The softscaled frequency compensation function is derived from a softscaled ratio between a time integrated output and a time integrated input power density functions. The first quality measure is derived from the difference loudness density function as function of time and frequency, using the frequency compensated input loudness density function and the gain compensated output loudness density function both as a function of time and frequency, in the same manner as carried out in ITU standard P.862. The second measure is established from a difference loudness density function as function of frequency only that is derived from a time integration of a second frequency compensated input loudness density function and the gain compensated output loudness density function both as a function of time and frequency.

Frequency compensation for perceptual speech analysis

Method and system for measuring transmission quality of an audio transmission system under test. Specifically, an input signal (X), such as an original input speech signal, is applied to the audio transmission system which results in an output signal (Y) produced by the transmission system. Both signals X and Y are mutually processed to yield a perceived quality signal. In accordance with the invention, output signal Y and/or input signal X are scaled such that, depending on a ratio of power of these two signals, relatively small deviations of power between these signals are compensated, while relatively larger deviations are only partially compensated. Further, an artificial reference speech signal may be created for which noise levels present in the input speech signal are reduced by a scale factor which reflects a local level of the noise in that input signal.

Method and system for measuring a system's transmission quality

Methods and devices for objectively predicting perceptual quality of speech signals degraded in a speech processing/transporting system which may have poor prediction results for degraded signals including extremely weak or silent portions. Improvement is achieved by applying a first scaling step in a pre-processing stage with a first scaling factor which is a function of a reciprocal value of power of the output signal increased by an adjustment value, and by a second scaling step with a second scaling factor which is substantially equal to the first scaling factor raised to an exponential value and with an adjustment value between zero and one. The second scaling step may be performed at various locations in the device. The adjustment values are adjusted using test signals with well-defined subjective quality scores.

Method and device for determining the quality of a speech signal

For measuring the influence of noise on the talking quality of a telephone link in a telecommunications network, a talker speech signal (s(t)) and a degraded speech signal (s'(t)) are fed to an objective measurement device for obtaining an output signal (q) representing an estimated value of the talking quality. The degraded signal includes a returned signal (r(t)) originating from the network during transmission of the talker speech signal over the telephone link. The objective measurement provided by the device is a modified PSQM-like measurement, which is modified to include modelling of masking effects resulting from noise present in the returned signal. Preferably, the modelling includes noise suppression performed on a difference signal (D(t,f)) in a loudness density domain using noise estimation.

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Hengstdijk, Netherlands

John Gerard Beerends