single and multi channel feature enhancement for …：单通道和多通道的功能增强…

Single and Multi Channel Feature Enhancement for Distant Speech RecognitionJohn McDonough(1) , Matthias Wlfel(2), Friedrich Faubel(3)(1) (2)Saarland UniversitySpoken Language Systems(3)TUTORIALTUTORIALI - Applications of DSRII - Characteristics of Human SpeechIII - The Acoustic EnvironmentIV - Speech feature enhancementV - Speaker TrackingVI - Digital Filter BanksVII - BeamformingOverviewTUTORIALTUTORIALPart IIIThe Acoustic EnvironmentTUTORIALTUTORIAL Sound PropagationSound Wavesn Sound waves are disturbances of air molecules, which propagate as wave fronts of compressed air, followed by decompressed air. sound sourcespeed of soundwave frontattenuationTUTORIALTUTORIAL Sound PropagationSuperpositionn Sound waves follow the law of superposition, i.e. individual waves from different sources add up at each point in the room.source 1source 2source 3TUTORIALTUTORIAL Sound PropagationReflectionn Sound waves are reflected by obstacles, such as walls, columns, chairs and tables.TUTORIALTUTORIAL Sound PropagationReflectionn Sound waves are reflected by obstacles, such as walls, columns, chairs and tables.TUTORIALTUTORIAL Sound PropagationReflectionn Sound waves are reflected by obstacles, such as walls, columns, chairs and tables.TUTORIALTUTORIAL Sound PropagationReflectionn Sound waves are reflected by obstacles, such as walls, columns, chairs and tables.TUTORIALTUTORIAL Sound PropagationReflectionn Sound waves are reflected by obstacles, such as walls, columns, chairs and tables.TUTORIALTUTORIAL Sound PropagationAbsorptionn Obstacles do not only reflect sound. They also absorb some portions in a frequency dependant manner.frequency- dependant absorptionTUTORIALTUTORIAL Sound PropagationColorationn Constructive and destructive interference of reflections can cause comb filter like “coloration” of the sound.TUTORIALTUTORIAL Sound PropagationColorationn Constructive and destructive interference of reflections can cause comb filter like “coloration” of the sound.TUTORIALTUTORIAL Sound PropagationColorationn Constructive and destructive interference of reflections can cause comb filter like “coloration” of the sound.TUTORIALTUTORIAL Sound PropagationColorationn Constructive and destructive interference of reflections can cause comb filter like “coloration” of the sound.=amplificationTUTORIALTUTORIAL Sound PropagationColorationn Constructive and destructive interference of reflections can cause comb filter like “coloration” of the sound.=attenuationTUTORIALTUTORIALn Constructive and destructive interference of reflections can cause comb filter like “coloration” of the sound.amplitudefrequencySound PropagationColorationTUTORIALTUTORIAL Sound PropagationDiffractionn Sound waves spread out behind small openings and bend around corners.TUTORIALTUTORIAL Sound PropagationOther Effectsn Refraction: wave passes from one medium to another at an anglen Scattering: diffuse reflections of wavesn Surface waves: longitudinal and transverse motion along surfaces; lower attenuation than normal sound wavesTUTORIALTUTORIAL Room Impulse ResponseIntroductionn Model for a single sound source with one reflection:sourcedirect pathlistenerwallreflectionTUTORIALTUTORIAL Room Impulse ResponseIntroductionn Model for a single sound source with one reflection:TUTORIALTUTORIAL Room Impulse ResponseIntroductionn Model for a single sound source with one reflection:n Generalization:TUTORIALTUTORIAL Room Impulse ResponseIntroductionn Model for a single sound source with one reflection:n Generalization:n Impulse response model:TUTORIALTUTORIAL Room Impulse ResponseIntroductionn Model for a single sound source with one reflection:n Generalization:n Impulse response model:with impulse responseTUTORIALTUTORIAL Room Impulse ResponseIntroductionn Model for a single sound source with one reflection:n Generalization:n Impulse response model:timeintensityTUTORIALTUTORIAL Room Impulse ResponseReinforcement reinforce the sound (35ms).timeintensityearly reflectionsTUTORIALTUTORIAL Room Impulse ResponseReinforcement reinforce the sound (35ms).n Late reflections: reflections with lower amplitude that are closely spaced in time; responsible for “reverberant” sound.timeintensitylate reflectionsearly reflectionsTUTORIALTUTORIAL Room Impulse ResponseEchon Echo: distinct, strong late reflection with a delay of more than 100ms.timeintensitylate reflectionsearly reflectionsTUTORIALTUTORIALClose Talking versus Distant Speechn Reverberation smears spectra in timen Noise fills spectral valleysclose talking . distant .TUTORIALTUTORIALEffects of Noisen Shown