Even for the dispatcher with the lowest exposure through their headset (59.4 dBA), the
ambient noise level in the call center contributed only to a minor extent to his overall daily noise exposure (61 dBA).
The upper two data records were made in the environment with a 55 dB SPL
ambient noise level. Note the attenuation of the wave forms in the nonplugged ear canal condition.
Thermostatically controlled cooling fans reduce the
ambient noise level to comply with noise regulations.
Results showed that acoustical material treatment such as absorptive ceiling tile and carpet did lower the
ambient noise level (or the low-end) by just perceptible amounts; however, the peak levels (or high-end) did not vary greatly except in the neonatal intensive care unit (NICU), where other environmental controls have been instituted.
Ambient noise level.
Ambient noise levels for the selected locations were collected using the Leutron make noise level meter.
Initial data are: the geometry of domain, machine sound levels and positions and the
ambient noise level. First a mesh of the area must be obtained.
In addition, each site had to have an
ambient noise level that was equal to or less than the average level of "quiet" for residential intersections in that area.
One of the biggest contributors to a classroom's
ambient noise level has traditionally been a school's HVAC system, regardless of whether it is roof mounted or wall mounted.
To ensure intelligibility and minimize annoyance from
ambient noise levels, the voice signal at a conferencing microphone needs to be at least 25 dB sound pressure level above the
ambient noise level.
As well as logging each use, the software 'learns' from it, tailoring itself to each airport, for example remembering the
ambient noise level at specific locations to provide the correct distress call broadcast volume.
These processes all contribute to the
ambient noise level from frequencies below 1 Hz to 50 kHz (NRC 2003).
In addition, the PCs operate at 14dB(A) quieter than other desktop PCs and below the
ambient noise level of a classroom.