Design with Acoustics in Mind

DESIGN WITH ACOUSTICS IN MIND

Presented by: Sean Connolly

(406) 457-0407 www.bigskyacoustics.com

Acoustical Design: • Ensure building or room is functional. • Design and develop practical, cost-effective options. • Unbiased technical analysis, not guesswork. • Meet Green Building requirements. Problem: • Everyone knows enough to be dangerous. • Acoustics = 1st thing cut out of budget, - But, 1st thing noticed when bad. Outline: • Acoustics 101 • Reverberation •Isolation • Ventilation ACOUSTICS 101 SOURCE PATH RECEIVER • Sound is a vibration. • Sound travels in waves out from source - spherically. • Sound is made up of many frequencies, each with its own wavelength …

… just like light. • Different frequencies create different sounds.

• Each frequency has its own sound level.

• Combine to determine overall noise level.

REVERBERATION ROOM ACOUSTICS

Source, path & receiver in same room. Reverberation: • Physical property of room • Room volume • Finishes (reflect or absorb) • How the room “sounds” vs. its use • Does not depend on sound system

Why is Reverberation Important?

. Quality of sound Why is Reverberation Important?

• Communication - Garbled speech - Can’t understand speech - Can’t hear person

Long T60

Short T60 Why is Reverberation Important?

• Overall noise levels - “Too loud in here” Material & Finishes

• Noise Reduction Coefficient (NRC) rating

• 0.0 = no sound absorbed

• 1.0 = all sound absorbed Material & Finishes

• Frequency dependent • Thick/heavy materials = bass • Thin porous materials = highs • Balance absorptive & reflective surfaces • Design goal? ISOLATION SOUND ISOLATION

Source & receiver in adjacent rooms. Path through partition. Sound Isolation

. Transmission loss (TL) – frequency dependent . Sound Transmission Class (STC) rating Why is Sound Isolation Important? . Limit distractions from outside room or building Why is Sound Isolation Important? . Dissimilar adjacencies and uses Why is Sound Isolation Important? . Privacy Concerns

• Gaps & holes • Weak elements Concerns

• Mass = more isolation Walls

• Mass • Separation • Low freq. concerns • Insulation • Single-stud, single layer GWB is not enough! Concerns

• Partial-height walls VENTILATION MECHANICAL SYSTEM NOISE & VIBRATION

Source is equipment. Paths are many. Receiver in room or outside.

Why is Mechanical System Noise & Vibration Important? . Background noise . ASHRAE design guidelines . Green building criteria

BG Why is Mechanical System Noise & Vibration Important?

. Neighbors . Noise regulations Noise Control • Duct liner • Attenuators • Operating conditions • Barriers • Enclosures Vibration Isolation • Absorbs vibrations • Internal vs. external “Kick the tires” CONCLUSION CONCLUSION • Reverberation •Isolation • Ventilation

• www.ncac.com Questions?

Thanks!

Sean Connolly Big Sky Acoustics, LLC (406) 457-0407 www.bigskyacoustics.com