For an experiment on the impact of traffic noise on bird behaviour, I tried to playback some low frequency traffic noise with a fixed amplitude. While (trying to) adjust the noise amplitude, I realized that the loudspeaker was quite unreliable: the amplitude of my playback varied by 3-10 dB from one day to the next although I had not changed any parameter or touched any button (and I always made sure that the battery was fully charged before use).

Has someone already experienced this? Any idea where this could be coming from and what to do to fix it?

Has someone any suggestion for a reliable device that would accurately render low frequency sounds?

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    $\begingroup$ It might be helpful to share the setup you are using (including the specific model of the hardware devices). $\endgroup$
    – Shannon
    Commented Jul 7, 2022 at 14:02
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    $\begingroup$ Please define the frequency range of 'low frequency' sounds for this experiment? The term by itself can be a bit subjective based on the study system one is based in? $\endgroup$
    – Thejasvi
    Commented Jul 7, 2022 at 22:22
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    $\begingroup$ A typical consumer amplifier + loudspeaker shouldn't vary in amplitude by that much between consecutive days, there might be something else going on. More information about your test setup is definitely needed in order to understand what is going on: what devices are you using, what are the frequency range of your signals, what are the relative positions of your speaker and receiver, is the test being performed indoors/outdoors, etc. Could it be that your environment is noisier on some days but not others? Could you be picking up wind noise? $\endgroup$ Commented Jul 8, 2022 at 10:14

1 Answer 1


The described phenomenon I would attribute to a loose connection or a cracked piezo-ceramic in the transducer. Check the capacitance of the transducer, clean and check all connectors. Go along the signal chain and check where the varying gain happens.


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