Sound Pressure Level, loudness and intensity
are not the same things. Human hearing is more sensitive to some
frequencies than others and furthermore its frequency response varies
with level. The most common method of measuring perceived loudness is the
Sound Pressure Level (SPL) meter with an dB(A) Weighting. This weighting
basically adjusts the value of the SPL measurement based on the curve
below.
Using the above weighting curve we
can gauge the relative impact of environmental noise on our hearing. The
sone is a unit of measure of the perceived loudness of sounds. It is
commonly used in the assessment of such things as mechanical noise. Many
SPL meters do not measure sones directly so we must convert from the
common dBA scale available on most units. The graph below approximates
the conversion to an accuracy of about 2dB.
Sonic beacon is a Canadian
organization founded in 1997. It is located in Pakenham Ontario which is near Ottawa, Canada. Ottawa is also home to
the National Research Council of Canada's anechoic chamber, a key
facility for acoustics testing. The chamber has been instrumental in the
development of Canadian loudspeakers, hearing aids and microphone arrays.
July 8, 2009: Sonic beacon Version 1.1.0.6 released. Data-Logger
can now save in .FRD and .ZMA file format. Data-Logger and Spectrum
Analyzer can perform .FRD and .ZMA clipboard copy transactions. Signal
generator can output signal complements on each sound card channel to
allow bridging in many consumer audio interfaces. Module status bar shows
current data type, FFT size and sample rate
