Hello,

Bioacoustics is a field that deals primarily with animal vocalization, sometimes in relation to anthrophony. For example, one could conduct bird song recordings to assess the masking effect of noise in animal communication.   

Some researchers conduct their recordings using remote sensing techniques. They deploy several omni-directional sensors in multiple sampling spots across the landscape in order to simultaneously conduct recordings of all significant events taking place in the soundscape, for a long period of time.

In order to obtain a realistic portrayal of the overall soundscape, meaning to capture the majority of the acoustic events taking place in a 24-hour period, it is necessary to organize your sampling protocol accordingly.  

The duration of the analyzing procedure depends on the software you are using. “R statistics” (with the appropriate packages) is very good and free but occasionally time consuming.       

For further information on recordings conducted for Bioacoustics, Soundscape Ecology and Ecoacoustics research, refer to articles written by Bernie Krause, Almo Farina and Henrik Brumm.

This depends a lot on what your goal is.

First, you should be aware of time scales of change in environmental sound. Depending on the environment, sounds may occur at fixed times, but most usually we would think of events occurring to a large degree randomly. To get a good coverage, you therefore has to consider the typical duration of the relevant sounds as well as their probability of occurrence.

Next, you have time-dependence of these values. For example, they obviously vary over the daily cycle - day and night sounds are different. However, there are also longer cycles (e.g. in human environments you may have weely cycles, with weekends different from weekdays; and there may be yearly cycles, with e.g. different animals active at different times of the year).

Finally, there are 'non-stationairites' - sounds that would occur for limited periods of time only (e.g., again in human environments, construction sounds).

When designing a study of an acoustic biotope, you have to take into account these issues in order to design a sampling schedule. You can ignore some of them, but if you do, be aware of it and have a way to justify it.

Dear Marianne,

In addition to Israel's excellent comments, I would add that there are also longer-term processes such as seasonal components.  For example, migratory birds might contribute to the soundscape during certain times of the year.  In ocean environments, you may find that rougher winter seas contribute to louder noise reducing the area of which sounds can be detected.  There are even longer-term processes that could also be studied (e.g. the Pacific decadal oscillation).  So, as Israel said, how you need to record for really depends on what question to you want to ask.

Best regards - Marie

PS - Remember that when you are sampling with acoustics, you are sampling over a relatively small area of most habitats and like any census tool, you need to think about survey design in ways similar to those that you might think about for a visual survey.