<p><em>If localisation needs to be done</em>: Figuring out the inter-receiver offset is the main challenge. This problem has been dealt with in this paper by <a href="https://link.springer.com/chapter/10.1007/978-3-642-45346-5_8" rel="nofollow noreferrer">Burgess et al. 2013</a>. In the paper the authors study how to acoustically localise unsynchronised receivers and sources using time-difference-of-arrivals.</p>
<p><em>If localisation isn't a priority</em>: Not a dolphin person here - please account for this :). With bats, one can assume a call rate of ~10 Hz ('normal' orientation echolocation), and thus seeing about 50 calls a second on a single-channel recording, one could arrive at a ballpark of 5 bats. Perhaps a similar calculation could be done with dolphin clicks. Since there are 5 'phones, perhaps the estimate will end up being better?</p>

CC BY-SA 4.0
2022-07-05T10:33:34.177Z
Potentially relevant answer: https://bioacoustics.stackexchange.com/a/243/131
Thejasvi
CC BY-SA 4.0
2022-07-05T08:44:52.060Z
2022-07-05T08:44:52.060Z
Thejasvi
<p>Yes (sort of)! Especially if you are using clicks. You can set this up in PAMGuard with the array structure as you described and it can calculate bearings and bearing crosses for localization. From localizations to number of animals requires a tracking algorithm, P. Gruden has a few out.</p>
<p>EDIT: <a href="https://asa.scitation.org/author/Gruden%2C+Pina" rel="nofollow noreferrer">Here</a>'s a link to some of P. Gruden's publications with the Journal of the Acoustical Society of America (JASA).</p>

CC BY-SA 4.0
2022-07-07T15:24:43.363Z
@fabio_hirono can you add that link into the answer text as an edit? Sometimes things get lost down in the comments. Thanks for adding it :)
selene
CC BY-SA 4.0
2022-07-04T05:12:32.660Z
Not sure if PamGuard can do that when the ST300s are not synchronized. You would need much more recorders to also estimate the time difference.
WMXZ
CC BY-SA 4.0
2022-07-04T12:45:25.910Z
Do you have a link available for P. Guden's algorithms?
Chloe
CC BY-SA 4.0
2022-07-04T13:39:57.520Z
@WMXZ ahh, right. Plus they drift a lot.
K.J. Palmer
CC BY-SA 4.0
2022-07-05T10:33:36.060Z
Here's a link to P. Gruden's publications in JASA: https://asa.scitation.org/author/Gruden%2C+Pina
fabio_hirono
CC BY-SA 4.0
2022-07-03T20:01:36.833Z
2022-07-07T17:05:03.737Z
2022-07-07T17:05:03.737Z
K.J. Palmer
<p>I have some recordings from an array of 5 ST300 stationary recorders, which recorded overnight during calm weather. Our recorders were set up in a square, with 25 m between each corner and one logger in the center, 2 m above the bottom in 10m deep water. We have 3 complete encounters of vocal activity, whistles and clicks, that were recorded on all 5 sound loggers. Our sampling rate was 96 kHz.</p>
<p>Are there methods to determine group size, or at least number of vocalizing animals, based on our set up?</p>

<localization><density-estimation><dolphins>
Can you derive group size from a recording of dolphins?
# Can you derive group size from a recording of dolphins?

(Asked by: username_0 on 2022-07-03)

I have some recordings from an array of 5 ST300 stationary recorders, which recorded overnight during calm weather. Our recorders were set up in a square, with 25 m between each corner and one logger in the center, 2 m above the bottom in 10m deep water. We have 3 complete encounters of vocal activity, whistles and clicks, that were recorded on all 5 sound loggers. Our sampling rate was 96 kHz.

Are there methods to determine group size, or at least number of vocalizing animals, based on our set up?

**Tags:** localization, density-estimation, dolphins


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## 2 answers

### Answer by username_2 on 2022-07-03. Score: 9 | Accepted answer

Yes (sort of)! Especially if you are using clicks. You can set this up in PAMGuard with the array structure as you described and it can calculate bearings and bearing crosses for localization. From localizations to number of animals requires a tracking algorithm, P. Gruden has a few out.

EDIT: [Here](https://asa.scitation.org/author/Gruden%2C+Pina)'s a link to some of P. Gruden's publications with the Journal of the Acoustical Society of America (JASA).

> **Comments:**
> **username_4**: Not sure if PamGuard can do that when the ST300s are not synchronized. You would need much more recorders to also estimate the time difference.  
> **username_5**: Do you have a link available for P. Guden's algorithms?  
> **username_2**: @username_4 ahh, right. Plus they drift a lot.  
> **username_6**: Here's a link to P. Gruden's publications in JASA: https://asa.scitation.org/author/Gruden%2C+Pina  
> **username_3**: @username_6 can you add that link into the answer text as an edit? Sometimes things get lost down in the comments. Thanks for adding it :)  

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### Answer by username_1 on 2022-07-05. Score: 2

*If localisation needs to be done*: Figuring out the inter-receiver offset is the main challenge. This problem has been dealt with in this paper by [Burgess et al. 2013](https://link.springer.com/chapter/10.1007/978-3-642-45346-5_8). In the paper the authors study how to acoustically localise unsynchronised receivers and sources using time-difference-of-arrivals.

*If localisation isn't a priority*: Not a dolphin person here - please account for this :). With bats, one can assume a call rate of ~10 Hz ('normal' orientation echolocation), and thus seeing about 50 calls a second on a single-channel recording, one could arrive at a ballpark of 5 bats. Perhaps a similar calculation could be done with dolphin clicks. Since there are 5 'phones, perhaps the estimate will end up being better?

> **Comments:**
> **username_1**: Potentially relevant answer: https://bioacoustics.stackexchange.com/a/243/131  

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