HVAC Noise in Hotels

sleep

(Image courtesy of A. Bhatia)

Hotels have central heating, ventilation and air conditioning (HVAC) systems which generate noise that may disturb guests’ sleep.  The noise propagates through ducts and room surfaces.

Individual room air conditioning units may also cause unpleasant noise.

The transmission paths in the diagram above include

1.  Duct-borne Noise
2.  Radiated Equipment Noise
3.  Duct Break-in Noise
4.  Duct Break-out Noise
5.  Terminal Noise through Grilles or Diffusers

* * *

The HVAC noise consists of

a.  Low-frequency fan noise – fans generally produce sound in the 16 Hz through 250 Hz octave bands.

Most of the energy a fan creates has a tone at the blade passing frequency and its integer harmonics. The blade passing frequency equals the fan rpm multiplied by number of blades in the rotor divided by 60.

b.  Low to mid-frequency variable-air-volume (VAV) box noise is usually in the 125 Hz through 500 Hz octave bands.

c.  Mid-frequency airflow or turbulence-generated noise – velocity noise from airflow and turbulence in a duct ranges from 31.5 Hz through 1 KHz.

d.  High-frequency damper and diffuser noises – usually in the 1 KHz through 4 KHz bands.

* * *

Here are a few anecdotal accounts:

Radisson Hotel Saskatoon
Bethesda Court Hotel
Bloomington – Normal Marriott Hotel
SpringHill Suites Chicago Southwest at Burr Ridge

* * *
Here are some references for HVAC noise:

HVAC Acoustic Fundamentals
Overview of Noise Control and HVAC Acoustics in Buildings

See also the ASHRAE Handbook

* * *

I recommend:  Bose Noise Cancellation Headphones

– Tom Irvine

2 thoughts on “HVAC Noise in Hotels

  1. Pingback: Bose QuietComfort 3 Acoustic Noise Cancelling Headphones | Vibrationdata

  2. A great as the Boses might be – this is not really what I would call a “solution”.

    a) I would always eliminate the problem at the source

    b) the active noise-cancelling effect gets weaker towards the low end, therefore, the RATIO between Lqc and Lqa gets WORSE, resulting in a signal with lots of LFN and very little signal power in the middle frequencies – a situation where the “spectral balance” is lost (masking effects that protect the ear can’t kick in).

    This situation is actually WORSE for our auditory processing mechanisms than the original signal (see: Krahe 2008, Genuit 2007, Burt 1996, Kröling 1985 – quoting from the top of my head here) … and indeed there are reports from users of noise cancellation headphones who use them on planes: “the noise is gone but suddenly I get seasick!” – sure, the remaining low frequencies “tickle” your auditory brainstem, leading to the phenomenon of sound-induced-motion-sickness…

    Yes, it does take a while (1-8 weeks of exposure) for these effects to develop, so the guy on the plane probably has been sensitized (maybe in his open plan office with nice standing waves of 7-30Hz) or by a weak form of a defect of his temporal bone (SCD syndrome).

    – Simon

    PS: LFN from hotel ACs IS a big problem for me, so I had silicone earplugs made (cost = around 100 bucks) … better spectral balance, don’t need batteries, tiny and … um … fashionable if you get them in PINK ;-)

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