Multichannel Natural Music Recording 1 Based on Psychoacoustic Principles
4/14/2015€¦ · • Sound waves are fluctuations in air pressure across time What is Sound?...
Transcript of 4/14/2015€¦ · • Sound waves are fluctuations in air pressure across time What is Sound?...
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TLP Provider Certification Course
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10 Hz – 100,000 Hz
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• Sounds are created when objects vibrate
• Sound waves are fluctuations in air pressure
across time
What is Sound?
Resonance
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Psychological study of
human perception of sound
Psychoacoustic Foundation
• Frequency
• Amplitude
• Time
• Space
• Sound determined by the frequency of vibration
• 1 Hertz (Hz) equals the vibration repeating itself once
• 20 Hz- 20,000 Hz human range
• Pitch- perceived frequency of sound
• Infrasonic- below 20 Hz
• Ultrasonic- above 20,000 Hz
• Music – instruments
• Language- phonemes
Frequency
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• The magnitude of increase or decrease of a sound wave
• Amplitude is perceived as loudness
• Loudness is measured in decibels (dB)
• Decibel scale is logarithmic
• Louder the sound the higher the decibel, softer the lower
• Less than 75 dB is considered safe
• Exposure of 85 dB+ over time, and 110 dB+ occasionally,
can cause permanent hearing damage
• Listen at comfortable levels
• Most foam or wax earplugs lower loudness by up to 29 dB
Amplitude
• Sound is an event in time
• Chronobiology examines biological rhythms
• Tempo is the pace of movement or beats; the speed
of music
• Rhythm is the organization of movement, or beats,
in time; the pulse of music
• Entrainment is the synchronization of rhythms
• Prosody example “I want another mother”
Time
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• Sound localization
• Interaural time difference (ITD)
• Interaural level difference (ILD)
• Where we are in the world
• Critical to survival
• Pinna
• Spatial organization of the system
• Frequency, volume, time
Space
Miracle Ear!
Frequency Volume Time Location
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Outer Ear (pinna, ear canal,
tympanic membrane)
Middle Ear (ossicles, muscles, eustachian tube)
Inner Ear (cochlea,
vestibular system)
3 Divisions of the Ear
Outer Ear
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Middle Ear
Source: Coloring Guide to Human Anatomy, Alan J. Twietmeyer
Middle Ear Muscles
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Middle Ear Fluid
Source: The Human Nervous System, Charles R. Novack
Inner Ear Labyrinth
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Source: Neuroscience: An Outline Approach, Anthony Castro
Cochlea
Source: Encyclopedia Britannica, Inc.
Vestibular System
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Auditory Transduction
The video will begin
following the narration.
Bone Conduction
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• Compressional
• Inertial
• Osseotympanic
• Cerebrospinal fluid
• Skull tissue
• Vibrotactile
More than “Bone”
• Dominant means of intrauterine listening
• Internal and external vibration
• A means of directly influencing the inner ear without
having to involve the middle ear
• A means of stimulating both the auditory and vestibular
apparati with sound at safe listening levels
• More safe and effective than air conduction as a means
of conducting sound as a stimulus for the vestibular
system
Unique Attributes of Bone Conduction
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• Activates receptors of both saccule and utricle (Curthoys
2010, Halmagyi 2005)
• Bilateral cochlear stimulation secondary to vibration
(Stenfelt 2002)
• Faster conduction speed than air conduction
• Tunes in from 10 Hz into ultrasonic range (up to 100 kHz),
with best vestibular-based responses within the low
frequency range (Nishimura et all 2002, Hakanssan et al
1996)
Unique Attributes of Bone Conduction
• Classical Auditory Pathway
• Classical Auditory Pathway Offshoots
• Non-Classical Auditory Pathway
• Autonomic Nervous System
• Enteric Nervous System
• Vestibular Pathways
• The Musical Brain
Pathways of Sound’s Influence
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Classical Auditory Pathway
• Inner Ear (Cochlea)
• 8th Cranial Nerve (vestibulocochlear nerve)
• Cochlear Nuclei
• Superior Olive
• Lateral Lemniscus
• Inferior Colliculus
• Thalamus- Medial Geniculate Nucleus
• Primary Auditory Cortex
Sources: Neuroscience: An Outline Approach, Anthony Castro | icg.harvard.edu/~psy1-s/ lectures/06sensation/
Tonotopic Map
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Offshoots
Reticular Formation
Auditory Association Cortex
Other cortical areas
Non-Classical Auditory Pathway
Limbic System
Cerebellum
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Autonomic Nervous System
Second Brain
Enteric Nervous System
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Vestibular Pathways
Spinal Cord
Eyes
More???
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Prefrontal cortex
Visual
cortex
Motor cortex Sensory
cortex Auditory cortex
Source: D.J. Levitin and A.K. Tirovolas/Annals of the New York Academy of Sciences 2009; Image: Charles Floyd.
The Musical Brain
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9 8 7 6
Cerebellum
Hippocampus
Amygdala
Nucleus accumbens
Source: D.J. Levitin and A.K. Tirovolas/Annals of the New York Academy of Sciences 2009; Image: Charles Floyd.
The Musical Brain
Listening is Active You listen with your brain
Auditory Processing What your brain does with what it hears
Hearing is passive You hear with your ears
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Adapted from Jay Lucker, EdD, CCC-A/SLP, FAAA
Six Integrated Systems
• Self regulation
• Auditory system
• Emotion
• Memory
• Language
• Cognitive decision making