HyperSonic Sound

1
HyperSonic Sound

• Audio Engineering Society
• Los Angeles Chapter Meeting
• Oct. 29, 2002

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What is HyperSonic Sound

• HSS is an Advanced Type of Parametric Loudspeaker
  System.
• A Parametric Loudspeaker System Uses the
  Nonlinear Properties of Air to Create Audio Sound
  Waves Within the Air Itself by Converting an
  Ultrasonic Set of Frequencies Into Sound That We
  Can Hear.

3
Basic Technology Introduction
f1 f2
(frequency)
f1
Sum
Air is aNon Linear Medium
f1
f2
f2
f1 - f2
Harmonics
DifferenceFrequency
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HSSTM
Move Fundamental Tones Beyond the Range of Hearing
91 kHz
50
20 Hz
51 kHz
20 kHz
1 kHz
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HSSTM Technology
Carrier Generator
HSS Processing Circuitry



Complex Audio IN
Input, EQ,DynamicsControl
HSSProcessing
Ultrasonic ModAmp
Complex Ultrasonic Waveform
SingleUltrasonicEmitter
Audible Sound is Demodulated by the Air Along the
Ultrasonic Column
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Ultrasonic Plane Waves
The Ultrasonic Energy Column ContainsHighly
Directional, Acoustical Plane Waves. These
Ultrasonic Plane Waves Create a Virtual End Fired
Array in Air !
Emitter
The Length of the Effective Ultrasonic Column
Determines the Directionality at Audio Frequencies
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Virtual End Fired Array
Raleigh Distance (Before Dispersion Begins) Based
on Operating Frequency and Emitter Diameter
Beam Dispersion Based on Operating Frequency and
Emitter Diameter
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How Do You Hear HSS?
ReflectingSurface
Sound Appears to Originate at Surface
X
No Sound
HSS UltrasonicEmitter
Direct Sound
Virtual Sound
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Ultrasonics and Audio
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History

• 1850, Helmholtz - Discovered the Nonlinear
  Property of Air Using Pipe Organ
• 1934, Thuras, Jenkins, ONeil - Extraneous
  Frequencies Generated in Air Carrying Intense
  Sound Waves
• 1939, Black - A Physical Analysis of Distortion
  Produced by the Non-Linearity of the Medium
• 1962, Westervelt - Parametric Acoustic Array
  (In Water)
• 1965, Berktay - Possible Exploitation of
  Non-Linear Acoustic in Underwater Transmitting
  Applications. Formulas For Squaring of the
  Signal in Air.
• 1975, Blackstock - Proves a Parametric
  Loudspeaker can Work With Air as the Transfer
  Medium.
• 1983, Yoneyama - Develops Double Sideband with
  Low Modulation Index. (To Achieve Distortion
  Reduction)

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History (cont.)

• 1984, Japanese Group - Implements Square Rooting
  to Minimize Parametric Distortion
• 1984-92, Japanese Group Continued Incremental
  Work with No Fundamental Progress
• 1996, Norris - Discovers Parametric Effects (with
  no awareness of the previous work)
• 1997/98, ATC - Discovers History and Previous
  Challenges
• 1997, ATC - Implements DSB with Square Rooting
  and Develops First Purpose Built Emitters
• 1999, ATC - Invents Recursive Inband Distortion
  Correction System
• 2001, ATC - Optimizes Manufacturing of PVDF
  Emitters, Adds Proprietary Modulation Amplifier
  (ModAmp)
• 2001, ATC - Develops High Power, Slotted Emitters
• 2002/03, ATC - Optimizes PVDF Emitter and
  Develops New Modulation Technique to Utilize
  Recursive Inband Distortion Correction System

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Parametric Loudspeaker Benefits

• Controlled Directionality - Direct a Column of
  Audio Where You Want It.
• Project Audio Over Long Distances While
  Maintaining Intelligibility
• Reduce Microphone / Speaker Feedback
• Ultrasonic Emitter Devices are Thin, Flat, Non
  Magnetic, No Vibration
• Non-Resonant Production of Audio Over the Entire
  Usable Bandwidth

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Previous Parametric Technology Challenges

• Double Side Band Modulation
• Square Root Processing

• Requirement for More Effective Distortion
  Reduction without Loss of Efficiency or Increased
  Transducer Bandwidth Requirement (Needed
  Theoretically Infinite Bandwidth)
• Requirement for High Efficiency, Phase Coherent,
  Monolithic, Purpose Built Ultrasonic Emitter
  (Transducer)
• Requirement for a High Efficiency, Ultrasonic
  Power Amplifier for Driving Reactive Loads
• Requirement for High, Continuous,Carrier
  Frequency Power

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HSS Specific Improvements

• Modified Side Band Modulation
• Recursive Distortion Correction
• Dynamic Carrier

• Greater SPL Output
• Monolithic Emitter Construction
• Narrow Bandwidth Modulation and Distortion
  Correction Technology
• Integration of High Efficiency Power Conversion
• Amplification and Modulation Created in a Single
  Process
• Dynamic Carrier Simultaneously Maintains Lowest
  Possible Ultrasonic Output Combined With Maximum
  Parametric Conversion Efficiency

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Bull Horn Communicator
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Drive Through Restaurants
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Museum Announcements
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Grocery Store Advertising
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Trade Show Exhibits
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Input Electronics
Remote Control
Status LED
Analog Input
Volume MUTE
HSS Logic PreProcessing
Compact Flash Memory Playback of .wav Files
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Potential Input Configurations

• Analog In
• Digital In
• AES/EBU
• SPDIF
• Ethernet
• Memory Card (.wav file playback)

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HSS Processing

• Dynamics (Audio Compression)
• Program and System EQ
• Recursive Distortion Control
• Proprietary Modulation
• Dynamic Carrier

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ModAmp Output Section
Power Supply
200 W ModAmp
Coupling Transformer and Magnetic Components
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ModAmp (Patented)

• Ultrasonic Switch Mode Amplifier
• 200 Watts
• 95 Efficient(Less Heat, Less Wasted Power)
• Integrated Modulation and Power Conversion
• Recycled Reactive Load Currents
• Miniature Size

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Ultrasonic PVDF Emitter (Patented)
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Emitter (Patented)

• PVDF Piezo-Electric Film Device
• Can be Manufactured for Any CarrierFrequency
  from Below 30 kHz to Beyond 100 kHz.
• Monolithic Construction Provides Phase Aligned,
  Coherent Wave Front
• High Output, Low Distortion

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Conclusion

• Demonstration of HSS System
• Questions Answers