Fitness Center Noise & Vibration Control

Scott Harvey, PE, INCE Bd. Cert.Phoenix Noise & VibrationFrederick, Maryland

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© Phoenix Noise & Vibration, LLC 2019

Learning Objectives

After attending this course, participants will be able to:

• Understand basic noise metrics• Differentiate between airborne noise and structure

borne noise• Identify the primary fitness center noise sources• Incorporate basic noise control techniques in fitness

room design

Noise Metrics

Rating Fitness Center Noise • Loudness

• Soft

• Quiet

• Loud

• Noisy

• Quality of Noise• Rumble

• Thumping

• Booming

• Banging

Terminology• Loudness measured in decibels (dB)

• dB = 10 x log(Pressure2/refPressure2)

• Human Range: 0 to 130 dB

• “A-weight” to simulate human hearing… “dBA”

Why dB???

• Reduces wide range of numbers to a smaller range:• 20 to 20,000,000 microPascals becomes 0 to 120 dB

• Example of the logarithmic nature:

• Eases Comparisons:30 to 33 = “Barely Perceptible”

90 to 93 = “Barely Perceptible”

Change in dB Subjective Response

3 dB Barely Perceptible

5 dB Clearly Perceptible

10 dB Twice as Loud

Terminology

•Everything is based upon the decibel scale

•It’s the fundamental unit of measure

• Frequency (tones) measured in Hertz (Hz)

• 1 Hz = 1 cycle/second

• Human range

• 20 Hz to 20,000 Hz

Sound Quality

• Named for Heinrich Rudolf Hertz

• 1857-1894

• Famous German Physicist

• First person to transmit

and receive radio waves

Sound Quality

Sound Quality

Put it all together…

0

10

20

30

40

50

60

70

80

63 125 250 500 1000 2000 4000 8000 16000

Sou

nd

Pre

ssu

re L

eve

l, d

B

Frequency, Hertz

• Single number ratings describing the relative loudness and speech interference properties of a given noise spectrum

•Used to specify background noise levels for various space uses, mainly HVAC and mechanical noise

Background Noise Measures

Background Noise Measures

• Noise Criteria (NC)

• Simple but,

• No assessment of sound quality

• Room Criteria (RC(N))

• More difficult to comprehend

• Evaluates sound quality

• Diagnostics

Mechanical Noise Measures

Method Loudness Quality

dBA • -NC • -RC • •

RC(N) • •

ASHRAE* Recommended Background Levels from HVAC sources…

* Values taken from 2011 ASHRAE Applications Handbook, Chapter 48, Table 1.

Room Type NC/RC dBA

Residences 25-35 30-40

Office buildingsExecutive and private offices 30 35

Conference rooms 30 35

Open Plan offices 40 45

Hospitals/Clinics

Private rooms 35 40

Wards 40 45

Operating Rooms 35 40

Laboratories(with fume hoods)

Testing/Research, minimal speech communication

55 60

Research, extensive telephone use, speech communication

50 55

Group teaching 45 50

Performing Arts Spaces 25 30

But what about Fitness…

• The challenging thing about fitness noise is that many times it is short term, impulsive noise which is more offensive than the constant humming or whirring of HVAC noise.

• Generally for such impulsive noises we aim for noise levels 5 dBA (or 5 NC) points quieter than those listed in the previous table.

But wait. What about vibration?

• Vibration: an oscillation of the parts of a fluid or an elastic solid whose equilibrium has been disturbed.

• Sound: vibrations that we hear

• Noise: unwanted sound (my neighbor’s home theater)

• It’s all vibration.

Air Bornevs.Structure Borne

Air Borne and Structure Borne

• Air borne noise and structure borne noise are really descriptors of the pathways by which sound arrives to the listener from the noise source.

Air Borne Noise Path

• The sound heard in the room which contains the source is transmitted through partitions and becomes air borne noise in other rooms.

• Generally air borne path starts as sound

• Example:

To Control Air Borne Noise…

• Use noise barriers to control or block air borne noise from other locations.

(remember this…quiz later)

Structure Borne Noise Path

• Vibration from the source is transmitted directly to the building structure, propagates through that structure and becomes audible sound in another part of the building.

• Generally structure borne is vibration

• Examples:

Pumps on the 4th floor

• Transmit structure borne vibration which was audible in a apartment bathroom on the 11th

floor!!!!

Structure Borne Noise

1. Ideally, if the vibrating object did not touch anything there would be no structure borne noise

2. Since #1 is pretty much a “no go”, proceed to #3

3. Introduce vibration isolation• Springs

• Neoprene (rubber)

• Polyurethane Foam

To SEPARATE the activity from the structure.

A little quiz…

Air borne?

Or

Structure borne?

Primary Fitness Center

Noise & Vibration Sources

Airborne Sources

American University Website

Structure BorneSources

American University Website

And for the queen mother…

•Crossfit

•Olympic Weightlifting

YouTube.com

Noise Control Techniques

Something better than muffs…

Location, Location, Location

•Ground level is preferable over elevated floors

•Away from living units and near occupied spaces

•Minimize the amount of shared partitions between the fitness center and living units

Hours of Operation

•Limit hours to the daytime

•Don’t allow late evening, nighttime, and early morning hours of operation

• Locate treadmills along exterior walls and column lines

•Place weight machines and other equipment away from living unit walls

•Avoid rigid attachments between amplified electronics and living unit partitions

Equipment Placement

Signage

Air Borne Noise Control

Blocking Noise

• There are noise barriers (blockers) and there are noise absorbers.

• Barriers are not absorbers.

• Absorbers are not barriers. • Many times the absorber is somewhat acoustically

transparent.

• Barriers are generally composed of dense, heavy material layers. (Quiz Later)

Quiz

• Barrier or Absorber?

• Barrier

Quiz

• Barrier or Absorber?

• Absorber

Quiz

• Barrier or Absorber?

• Barrier

Quiz

• Barrier or Absorber?

• Absorber

Quiz• Barrier or Absorber?

• This is of absolutely no use to the acoustician except to keep beer cold!

Side track…

• How do we rate partitions for barrier effectivenes?

Sound Transmission Class

or STC

Terminology

• Sound Transmission Class (STC) – a single number rating of the partition’s ability to block speech frequencies from one side to another.

• This is blocking AIRBORNE noise, not structure borne

Room to Room

STC Applies to BothFloor/Ceiling SystemsAnd Walls

Room to RoomSTC ASTC Subjective Description

30 22-25 Most sentences clearly understood

40 32-35 Speech can be heard with some effort

50 42-45 Loud speech can be heard with some effort

60 52-55Loud speech essentially inaudible. Minimum for loud, airborne fitness centers.

70 62-65 Loud music heard faintly

75+ Most noises effectively blocked

Credit: Architectural Acoustics: Principles and Design 1999

Room to Room Quiz…

STC not always right…

• STC developed for speech, applied to many other noise sources such as:

• Fitness

• Mechanical

• Transportation

• Music

• Warning: Not always accurate for these other sources, ESPECIALLY MUSIC THAT’S HEAVY ON THE BASS!!!

Back on the main track

Air Borne Noise Control

Ceiling Design•Design trend is a minimalistic or industrial look•Location Dependent•Only affective on the spaces above or below the ceiling•Consider sensitive spaces: lobbies, conference rooms, living areas, etc.•Spring Isolated ceiling significantly increases the floor/ceiling performance•But remember, High STC rating may be necessary. International Building Code (IBC) requirement of 50 STC and 50 IIC was designed around speech and footfall noise, not that of running or weight drops impacting the floor

Kinetic Noise Control

So to block airborne noise you have to use a wall and/or ceiling system with a high STC rating…greater than 65 for higher noise sources.

Structure Borne Noise Control

Structure Borne ControlIsolation at the source

• Isolation pads specifically designed for the exercise equipment

• Localized rubber mats beneath free weight and weight machine locations

• Specify rubber/urethane coated steel plates with bumper plates

Pliteq

Spring IsolatedHeavy Bag

Structure Borne ControlFloor Design

▪ Treadmill isolation pads are recommended with all resilient flooring thickness

Resilient FloorCardiovascular

Equipment

StationaryWeight

Machines

Free Weights

Group Exercise or

CrossFit

¼” Thick Underlayment •

1” Thick Rubber Flooring •

2.5” Thick Rubber Flooring •

Concrete Floating Slab •

Kinetics Noise Control

Mason Industries

In Review…

Noise MetricsAir borne

vs.Structure borne

Significant Sources

Noise Control Schemes

Fitness Noise & Vibration

Thank you for the Attention!

Questions or Discussion?