Acoustic Communications in Reverberant Rooms: Why is it easy for humans, but challenging for traditional digital communications technologies?

#spread-spectrum #acoustic
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This talk addresses the severe acoustic multi-path environment present in typical rooms (generic acoustic volumes), theoretical limits for information transfer in those room environments and techniques required for digital transmission in those environments.

To answer the question on why humans have little difficulty communicating in these challenging acoustic environments, the talk will provide a primer on room acoustics (e.g., critical distance, impulse responses), human hearing (e.g., loudness, auditory masking), and speech intelligibility (audibility index). Shannon bounds for reliable communications in such rooms will be discussed. The talk will conclude by describing one acoustic ultrasound Discrete Sequence Spread Spectrum (DSSS) technique that is widely used today in millions of Cisco


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  • Date: 25 Oct 2024
  • Time: 03:30 PM to 05:00 PM
  • All times are (UTC-04:00) Eastern Time (US & Canada)
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  • 4220 E Fowler Ave
  • Tampa, Florida
  • United States 33620
  • Building: Engineering Building II (ENB2)
  • Room Number: ENB 118
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  • Co-sponsored by FWCS Life Members Affinity Group
  • Starts 27 September 2024 12:01 PM
  • Ends 25 October 2024 07:00 PM
  • All times are (UTC-04:00) Eastern Time (US & Canada)
  • No Admission Charge




Agenda

Background

  1. Human Hearing Primer

    • Human Hearing Dynamic Range and Auditory Masking

  2. Room Acoustics Primer

    • Direct Sound / Early and Late Reflections / Impulse Response / Reverberation Metrics

  3. Speech Intelligibility / Speech Information Transfer Rates

    • Acoustic Information Transfer in Rooms

    • How Room Acoustics Affect Candidate Digital Communications Techniques

Digital Communications

  1. Spread Spectrum Communications in Multipath Environments

    • Code Division Multiple Access Examples (CDMAone and IS-95)

  2. Shannon Limit for Digital Communications in Multipath Environments (with high delay spread)

    • Can decode in negative SNR - but at low data rates.

  3. Putting It All Together: Using Discrete Sequence Spread Spectrum (DSSS)

    • An Ultrasound DSSS example

  4. Implications for Other Severe Multipath Environments