UNIT VI DSP in Speech Processing & Image Processing
Audio Processing: Human Hearing, Timbre, Sound Quality Versus Data rate, High Fidelity Audio, Companding, Speech Synthesis and Recognition, Non Linear Audio Processing Image Foundation and Display: Digital Image Structure, Cameras and Eyes, Television Video Signals, Other Image Acquisition and display, Brightness and Contrast Adjustments, Gray Scale Transforms Audio Processing Structure of the human ear
Human hearing Structureof thehumanear Phys1061, S.Boyd Click to add title Click to add text Important parts of the ear
Human hearing Important parts of the ear Outer Ear: Auditory canal Ear drum Middle ear: Ossicles: hammer (malleus), anvil (incus), stirrup (stapes) Inner Ear Cochlea Auditory nerve Phys1061, S.Boyd Frequency response localized in Cochlea
Neuronal Decoding of Sound (Schematic) Low Frequency High Frequency Frequency response localized in Cochlea Mechanism of signal transport
Human hearing Mechanism of signal transport Hall, Musical Acoustics, 3rd Ed. Phys1061, S.Boyd Copy out these notes Pinna = outer portion of ear used to collect sound waves Auditory Canal = tube that sound travels down Ear Drum = membrane that sends sound waves to hammer Hammer = first of 3 bones.It vibrates, striking the anvil to carry on the sound Anvil = gets hit by the hammer, striking the Stirrup Stirrup = vibrates against OVAL WINDOW, carrying on sound Cochlea = a spiral full of sensory hairs, which when bent, send an electrical signal to the AUDITORY NERVE Auditory Nerve = carries all signals for sound to brain SemiCircular Canals = full of gel-like material.Indicates if you are right side up or upside down. (Balance) Structure of the Ear designed to gather and collect sound into the ear canal
Outer Ear = Pinna designed to gather and collect sound into the ear canal Middle Ear the Auditory Canal
Channels the sound toward the EAR DRUM Middle Ear the Ear Drum is actually called the TYMPANIC MEMBRANE
Sound waves = vibrations HAMMER hits ANVIL moving the STIRRUP! What Happens Next? Sound waves travel into the SPIRALLED COCHLEA
Tiny hairs in the COCHLEA move to the beat, and send impulses along nerve fibers All nerve fibres link to the AUDITORY NERVE, to the brain. Inside the COCHLEA! Eustacian Tube Detectable Sound Levels What can the Machinery Pick UP? What Frequencies can we Hear?
Hz Hz Detectable Sound Levels What can be Heard? Sound Wave Production Levels of Intensity Soft (Low) Harsh(High) Defeating Deafness Cochlear Implants
The implant generates electric signals as the sound bounces off detector Vibrations = electricity Electricity stimulates the AUDITORY NERVE directly Protect your Hearing! Ear plugs Ear muffs Keep the volume down Spidey knows the Value of Protecting Your Hearing! Copy out these notes Pinna = outer portion of ear used to collect sound waves Auditory Canal = tube that sound travels down Ear Drum = membrane that sends sound waves to hammer Hammer = first of 3 bones.It vibrates, striking the anvil to carry on the sound Anvil = gets hit by the hammer, striking the Stirrup Stirrup = vibrates against OVAL WINDOW, carrying on sound Cochlea = a spiral full of sensory hairs, which when bent, send an electrical signal to the AUDITORY NERVE Auditory Nerve = carries all signals for sound to brain SemiCircular Canals = full of gel-like material.Indicates if you are right side up or upside down. (Balance) Inverse Square Law, Sound Units of sound intensity
Units of sound intensity. Sound intensity is expressed as power per unit area (such as watts/cm2), or more commonly on a logarithmic scale called decibels SPL(Sound Pressure Level). As this table shows, human hearing is the most sensitive between 1 kHz and4 kHz. Decibel levels of some common sounds
Sound Source Sound Pressure Level (dB) threshold of excellent youthful hearing normal breathing, threshold of good hearing 10 soft whisper 30 mosquito buzzing 40 average townhouse, rainfall 50 ordinary conversation 60 busy street 70 power mower, car horn, ff orchestra 100 air hammer at 1m, threshold of pain 120 rock concert 130 jet engine at 30m 150 rocket engine at 30m 180 More decibel levels here: Audio data rate vs. sound quality Laser Wavelength The Piano keyboard The keyboard of the piano is a logarithmic frequency scale, withthe fundamental frequency doubling after every seven white keys. These white keys are the notes: A, B, C, D, E, F and G. Pregroove on (Re)Writable Disks
empty track land mark (data) laser beam written wobbled pregroove (Re)Writable Disk CD stores about 1 bit per (m)2, corresponding to 1 million bits per (mm)2, and 15 billion bits per disk. Timbre Loudness: sound wave intensity
Pitch: fundamental component in the sound Timbre : harmonic content of the signal High Fidelity Audio Compact disc surface Playback-CD During playback, an optical sensor detects if the surface is reflective or nonreflective,generating the corresponding binary information. Binary one must be part of a group of 3 to 13 ones Two-level Reed- Solomon coding: combining the left and right stereo channels along with data for error detection and correction -Cont Compact disc playback block diagram
EFM: Eight-to-Fourteen Modulation Speech Synthesis and Recognition Human speech model Nonlinear Audio Processing
Homomorphic separation of multiplied signals Homomorphic separation of convolved signals