Lecture 9 Part 2

GUEST LECTURE BY THOMAS SELO

  • Date: October 1, 2025

  • Course: ARCHTECH 210 – Environmental Design

  • Focus: Indoor Acoustic Design

INTRODUCTION TO THE SPEAKER

  • Thomas Scelo

    • Experience in acoustics since 1999

    • Worked at Acoustic Testing Services for 3 years

    • PhD in Mechanical Engineering from UoA (2006)

    • Six years at the acoustic laboratory of the school of architecture

    • Consultant in acoustic design for building projects

    • Expert in Performing Arts acoustics (concert halls, opera houses, theatres, arenas, studios)

  • Notable projects:

    • Atelier Jean Nouvel, Philharmonie de Paris

    • Zaha Hadid Architects, Changsha Meixihu Opera House

    • BIAD, Guangzhou Shiyuan Concert Hall

    • Rieder Group, Historical Concert Hall Reconstruction

ROOM ACOUSTICS

  • Definition: Study of how a space responds to sound and how the response is perceived by people inside it

    • Characteristics quantified in both scientific, engineering, and subjective terms

  • Examples of subjective qualities:

    • Dead vs. Lively

    • Clear vs. Muddy

    • Quiet vs. Loud

  • Purpose:

    • To support functions of the space and the overall experience

    • For speech, less reverberation enhances intelligibility

    • Aimed at supporting communication

  • Historical context:

    • Room acoustics is as old as interior design and preceded writing

    • Key for knowledge transfer and storytelling

    • Notable historical examples:

    • Lascaux, France (30,000 BC)

    • Odeon of Herodes, Greece (450 BC)

    • Street Theatres, China (15th Century)

    • Versailles Hall of Mirrors, France (1684)

    • Haydnsaal, Schloss Esterházy, Austria (1766)

    • Concertgebouw, Amsterdam (1888)

    • Musikverein, Austria (1870)

  • Recommended reverberation times for different functions:

    • Speech, music, teaching, sport, etc.

    • Reverberation time criterion (RT or T60) varies with space volume

    • Reference: AS/NZS 2107:2016 (Recommended design sound levels and reverberation times for building interiors)

AUSTRALIA / NEW ZEALAND ACOUSTIC STANDARDS

  • AS/NZS 2017:2014

    • Widely used standard for interior spaces in New Zealand

    • Not a building code requirement, but project required

    • Benchmark frameworks:

    • Green Star NZ (IEQ)

    • WELL Building Standard

    • Ministry of Education (DQLS and newer Acoustic Design Requirements for Schools)

    • Auckland Unitary Plan

  • Defines two criteria for internal acoustics:

    • Design Sound Level:

    • Background noise levels from external sources (traffic, plants) and internal sources (HVAC, equipment)

    • Expressed in dBA, measured over a 15-30s period

    • Design Reverberation Time:

    • Based on typical dimensions, sensitivity of space, and specific requirements

ACOUSTICS IN EVERYDAY SPACES

RESIDENTIAL

  • The Curious Case of the Residential Project:

    • Standard provides noise levels but not reverberation time for habitable spaces

    • Small spaces filled with furniture and diffusing objects

    • Importance of considering acoustic defects and noise build-up in larger spaces

    • Modern design trends shifting away from carpet and low ceilings; focus on absorption in common areas

    • NZ townhouse example:

    • Repeated and mirrored designs, rectangular geometries, cost-effective finishes

    • High ceilings and glazing for better light

    • Result: sound reflecting interiors, long reverberation time until furnished, limited noise build-up control

OFFICE SPACES

  • Standard case of office space:

    • Design sound levels: 30 dBA to 50 dBA

    • Design reverberation time: short (0.4s to 0.8s)

  • Practical implications:

    • Expectation for absorptive ceilings using fiber tiles or perforated panels

    • All spaces should include carpet or vinyl

    • Private AV rooms require additional sound absorption on two walls

    • Large/shared spaces need sound absorptive panels on walls; meeting rooms require careful panel distribution

REFLECTIONS IN SPACE

  • Geometry of reflections:

    • Incident sound emitted from the source reaches reflecting surface

    • Sound energy reflects with the same angle (Φ); called specular reflection

  • With sound absorptive material (absorption coefficient α), reflection energy is reduced by α

  • Structure of reflections in time:

    • Time metrics for sound:

    • Direct sound (0-30ms)

    • Early reflections (0-50ms for ceiling, 0-80ms for sides)

    • Late reverberation (80ms onwards)

  • Reflections impact intelligibility, loudness, clarity, and envelopment (intimacy)

OPTIMISING REFLECTIONS

  • Strategies for optimization:

    1. Orientate and shape reflecting surfaces to control reflection direction

    2. Spread reflections among a wider audience

    3. Absorb reflections to control reverberation time

    4. Direct reflections into larger spaces to enhance reverberation time

ADDITIONAL REFLECTIONS ISSUES

ECHOES

  • Define: Occurs when a reflection arrives late, perceived as two separate events

    • Threshold: 50ms for speech, 80ms for music

  • Solutions:

    • Redirect reflections to less critical zones

    • Diffusion to scatter reflections

    • Absorb sound to eliminate echoes

FLUTTER ECHOES

  • Define: Occur with multiple surface bounces creating a “twang” sound

    • Fixes:

    • Angle walls to prevent reflection loops

    • Diffuse reflections on surfaces

    • Use absorption to reduce energy

FOCUS

  • Define: Occurs when sound is concentrated at a specific point

    • Solution:

    • Alter curvature of concave surfaces to prevent focus

    • Position focus away from listeners

    • Implement diffusion and absorption to manage reflections

REFERENCES

  • Aletta F., Kang J. Historical Acoustics – Relationships between People and Sound over Time. MDPI

  • Sabine P.E. (1932). Acoustics and Architecture. New York: MacGraw-Hill

  • Barron M. (2014). Auditorium Acoustics and Architectural Design. Routledge

  • AS/NZS 2107:2016 Standard, https://www.standards.govt.nz/shop/asnzs-21072016

  • Online acoustic glossary: https://www.acoustic-glossary.co.uk/

  • Egan M. D. (1988). Architectural Acoustics. New York: McGraw-Hill.

  • GIB Noise Control Systems: https://www.gib.co.nz/assets/Uploads/GIB-Noise-Control-Systems-Manual-May22.pdf

QUESTIONS?

  • Contact Information: Thomas Scelo

  • Event Info: ARCHTECH 210 Environmental Design

  • Date: October 1, 2025

  • Venue: Lecture Hall 150

GUEST LECTURE BY THOMAS SELO

  • Date: October 1, 2025

  • Course: ARCHTECH 210 – Environmental Design

    • This lecture is specifically tailored for students of environmental design, focusing on the critical role of acoustics in creating sustainable and comfortable indoor environments.

  • Focus: Indoor Acoustic Design

    • Exploring principles, standards, and practical applications for achieving optimal soundscapes within buildings.

INTRODUCTION TO THE SPEAKER

  • Thomas Scelo - Experience in acoustics since 1999

    • His extensive background demonstrates a deep understanding of both theoretical and practical aspects of sound.

    • Worked at Acoustic Testing Services for 3 years

      • Gained hands-on experience in measuring and analyzing acoustic properties of materials and spaces.

    • PhD in Mechanical Engineering from UoA (2006)

      • His doctoral research likely focused on the physics of sound, material science, or vibration control, providing a strong scientific foundation.

    • Six years at the acoustic laboratory of the school of architecture

      • This role involved applying acoustic principles to architectural design, bridging the gap between engineering and design.

    • Consultant in acoustic design for building projects

      • Provides expert advice on noise control, room acoustics, and sound insulation for a wide range of building types.

    • Expert in Performing Arts acoustics (concert halls, opera houses, theatres, arenas, studios)

      • This specialized area requires a nuanced understanding of how sound behaves in large, complex volumes, balancing clarity, resonance, and audience immersion.

  • Notable projects:

    • Atelier Jean Nouvel, Philharmonie de Paris

      • A prestigious project known for its innovative architectural and acoustic design, challenging traditional concert hall forms.

    • Zaha Hadid Architects, Changsha Meixihu Opera House

      • Showcases complex geometries and their impact on sound propagation and audience experience.

    • BIAD, Guangzhou Shiyuan Concert Hall

      • Exemplifies modern concert hall design principles, often incorporating variable acoustics.

    • Rieder Group, Historical Concert Hall Reconstruction

      • Demonstrates expertise in preserving and enhancing the acoustic properties of heritage buildings while integrating modern technology.

ROOM ACOUSTICS

  • Definition: Study of how a space responds to sound and how the response is perceived by people inside it

    • This includes phenomena like sound absorption, reflection, diffusion, and transmission, which collectively define the aural character of a room.

  • Characteristics quantified in both scientific, engineering, and subjective terms

    • Scientific metrics include reverberation time, clarity, definition, and sound pressure levels.

    • Subjective terms describe the perceived quality and comfort of the sound environment.

  • Examples of subjective qualities:

    • Dead vs. Lively: Refers to the amount of reverberation; a 'dead' room has very short reverberation, while a 'lively' one has long reverberation.

    • Clear vs. Muddy: Pertains to speech intelligibility or musical detail; 'muddy' sound means reflections obscure direct sound.

    • Quiet vs. Loud: Relates to the overall sound pressure level and background noise.

  • Purpose:

    • To support functions of the space and the overall experience

      • For example, different spaces require different acoustic treatments; a library needs quiet, a concert hall needs resonance, and an office needs speech intelligibility.

    • For speech, less reverberation enhances intelligibility

      • Excessive reflections can cause speech to become indistinct and difficult to understand.

    • Aimed at supporting communication

      • Good room acoustics ensure that spoken communication or musical performances are delivered effectively and appreciated without distortion or discomfort.

  • Historical context:

    • Room acoustics is as old as interior design and preceded writing

      • Early humans intuitively shaped caves or gathering places to optimize sound for communication and rituals.

    • Key for knowledge transfer and storytelling

      • Oral traditions relied heavily on spaces that amplified or clarified speech.

    • Notable historical examples:

      • Lascaux, France (30,000 BC): Prehistoric cave paintings often located in acoustically resonant chambers, potentially for ritualistic purposes.

      • Odeon of Herodes, Greece (450 BC): Ancient open-air theatres designed with specific geometries to project sound to large audiences without amplification.

      • Street Theatres, China (15th Century): Utilized natural acoustics and simple structures for performances.

      • Versailles Hall of Mirrors, France (1684): A grand, highly reflective space, acoustically very live, showcasing the aesthetic over acoustic comfort of the era.

      • Haydnsaal, Schloss Esterházy, Austria (1766): A Baroque concert hall prized for its warm, clear acoustics, suitable for classical music.

      • Concertgebouw, Amsterdam (1888): Renowned for its exceptional acoustics, often considered one of the world's finest concert venues due to its shoebox shape and material choices.

      • Musikverein, Austria (1870): Another