Converting mseed files to audio files

Usage Questions
1

I am working with some OBS data and would like to convert an mseed file to an audio file so that I can listen for sounds that may resemble fin whale calls, or determine if the signals are the cause of something else. In this case, I download an hour of data and apply a bandpass filter. The data is sampled at 200 Hz. I have tried saving the data to a wav file, but when listening to it, no sounds are produced.

Any suggestions would be greatly appreciated!

import obspy as op
from obspy.clients.fdsn import Client

client = Client("IRIS")
net = 'NV'
sta = 'NC89'

start_time = op.UTCDateTime("2020-04-02T12:00:00.000")
end_time = start_time + 3600
st = client.get_waveforms(net,sta,'*','HHZ',start_time,end_time)
st.detrend(type='demean')

st2 = st.copy()
st2.filter('bandpass',freqmin=5,freqmax=25)
2

Maybe you can try to shift the frequencies to a higher range by setting a different sampling rate. I think 25 Hz – your upper bound – is difficult to hear.

For example

for tr in st2:
    tr.stats.sampling_rate = 2000

Edit:

The sampling_rate is automatically adjusted when writing the wav file. Try to adjust the framerate paramter and/or the rescale parameter:

https://docs.obspy.org/packages/obspy.io.wav.html

https://docs.obspy.org/packages/autogen/obspy.io.wav.core._write_wav.html

3

Yes, I read the info about the framerate parameter. I tried the default 7000, as well as 2000, and 4000. No success so far.

4

It’s simply too quiet. I checked your example and it is working with

st2.write('test.wav', 'WAV', rescale=True, width=4)
5

compare fix wav rescale with default width=None by trichter · Pull Request #3029 · obspy/obspy · GitHub