today I stumbled upon one folder in my backups I totally forgot about. It contains an audio file, a spectrogram and some observation. In mid 2017 (starting from june) my speakers began to (seemingly randomly) play 1,4 seconds of the same audio during different times. It was a 1 kHz tone. You can check the full 1,4 seconds of the audio here:
It played at different times and I could not detect any process as the source of the sound. I could capture the sound through my sound card (Asus Xonar D1) though. Does anybody know what this sound means and why it could have been played? My observations:
- That sound was played more often between 00:00 and 02:00 UTC+2 (Germany)
- 1410 ms duration, 1 kHz frequency
- rise to amplitude in 9ms, comedown as well
I tried to reconstruct the durations of the sound and the silence in ascii:
Legend:
{DURATION} := Duration of the 1 kHz signal
[DURATION] := Duration of the silence
{ 209 ms } [ 58 ms ] { 74 ms } [ 58 ms ] { 74 ms A} [ 58 ms ] { 75 ms B} [ 191 ms ] { 76 ms C} [ 58 ms ] { 75 ms D} [ 191 ms ] { 209 ms }
A - additionally very weak signals appeared on an irregular basis during 7 ms
B - [...] 3 ms
C - [...] 5 ms
D - [...] 10 ms
Figure ( P = Pause (~58ms), E = One Unit of the sound (~75ms) ):
PPP E P E P E P EEE P E P EEE PPP
Message / Body maybe: E P E P E P EEE P E P EEE
Thanks in advance for everybody trying to solve the riddle.
Best regards,
sea212
