*What is -25 dB Signal to Noise Ratio (S/N)?
If a sound intensity is reduced by one-half it is
equivalent to a change of -3 dB. A
signal/ noise ratio of -25 dB means the sound source intensity is literally
about 300 times lower than the background noise intensity.
What
does this mean, can you give an example?
Imagine a soloist singing, the sound power is assumed to be unity.
Behind the soloist is a choir, each member is also singing with the same
unit intensity. If the choir has nine members singing, the signal to
noise ratio will be -10dB.
The human ear could just about pick out the
soloist with this overall level of background noise.
So
what is -25dB equivalent to?
If the number in
the choir is increased to about 300, all singing with the same intensity,
the soloist would be completely masked by the background noise. The
signal to noise ratio is now about -25dB. BatScan can both locate
and measure the sound intensity of the soloist.
The human
ear is an extraordinary instrument - but the BatScan system has greater
sensitivity and spatial discrimination.
Greene
R&D International (GRDI) Tomorrow's
Technology Today