The following files are WAV files that contain weak signals in white
The audio format is 16 bit mono at a sample rate of 44100 Hz.
The audio signal consists of a white noise background and a pulsed sine
wave signal. The sine wave has a frequency of 800 Hz and is pulsed at
2 Hz with 50% duty cycle. Each file has a duration of 10 s.
The white noise background has a level of 36 QU / sqrt(Hz), where QU
is one quantisation unit of the digitized signal. The amplitude of the
wave signal (during the periods where it is on) was adjusted to be equal
to the noise power within varoius bandwidths. The bandwidth in Hz is
indicated in the file name. For example, in the file bw1000.wav, the
sine wave has an RMS amplitude of 36 QU * sqrt(1000) = 1138.42 QU,
which corresponds to a maximum of 1609.97 QU. If this signal was
with a noise bandwith of 1000 Hz, an SNR of 0 dB would result.
You can check how well your brain filters the signal out of the noise by
listening to the following WAV files:
A nice tool that can be used to generate such data is R. You can obtain
from www.r-project.org. Once
you have R installed, you can use the
script weaksig.R to create WAV files like
those above. After starting R,
to create a file like the bw1000.wav above.