<p>As you wanted to monitor a rainforest ecosystem, which, I guess, lacks loud anthropogenic sound, you should use the system with the lowest system noise level (highest system SNR) to capture also quieter species. Only, if you restrict yourself to monitor loud fauna then you could accept higher system noise (lower system SNR).</p>

CC BY-SA 4.0
2023-01-19T22:27:04.623Z
Certainly, if budget was not a factor, using the highest SNR equipment available would achieve the most quality recordings and largest effective detection range. But considering the vast range in price of different units (AM currently \$94, the SM series ranging from \$250-900) I think the cost-benefit analysis becomes worth considering.

For example, to monitor a single area of interest one could purchase 1x SM4 or 9x AudioMoth units for the same price. Despite significantly lower SNR, the more dense sampling of the AudioMoth units would result in an effectively larger detection range.
giojacuzzi
CC BY-SA 4.0
2023-01-14T10:33:32.303Z
2023-01-14T10:33:32.303Z
WMXZ
<p>I'm assembling a PAM field kit for the upcoming breeding season in the temperate rainforest ecoregion of Washington, USA, and would love to learn about your experiences with different ARU (Autonomous Recording Unit) performance.</p>
<p>My use case is continuous (up to 24 hr) multi-day monitoring of avian/insect species and soundscape analysis throughout a landscape with varying habitats, sample rate ranging from 32-48kHz.</p>
<p>I'm weighing the pros and cons of two common ARUs, the AudioMoth (AM) and the Wildlife Acoustics Song Meter (SM) series (with the SM Micro being the most directly comparable). As with any product, the fundamental tradeoff is quantity vs quality. I'm interested in two particular features:</p>
<p><strong>1) Detection range.</strong></p>
<p>Signal-to-noise ratio is perhaps the greatest factor determining detection range. Theoretically, every additional 6dB doubles the distance at which a signal can be detected.</p>
<p>SNR for the AudioMoth is <a href="https://www.openacousticdevices.info/audio" rel="nofollow noreferrer">44 dB</a>, while Song Meters range from <a href="https://www.wildlifeacoustics.com/products/song-meter-sm4-vs-mini-vs-micro" rel="nofollow noreferrer">73-80 dB</a>. SNR <a href="https://peerj.com/articles/9955/" rel="nofollow noreferrer">has been found</a> to increase detection space in the human-audible range by a factor of 1.7 when comparing a 55 to 80 dB SNR microphone. <a href="https://besjournals.onlinelibrary.wiley.com/doi/epdf/10.1111/1365-2664.13229" rel="nofollow noreferrer">Another study</a> pitting the performance of manual human detection of birds against ARUs found that a 72 dB SNR was roughly comparable.</p>
<p><a href="https://avianeco.com/wp-content/uploads/2022/12/White-Paper-AMSMTesting.pdf" rel="nofollow noreferrer">One evaluation</a> in an open wetland environment saw the AM perform somewhat comparably to the SM4 within 100 meters in terms of detection vs distance, but with a difference of up to -13% of target stimuli captured from various biotic and abiotic signals. Certainly, the more dense the habitat vegetation the more attenuation we'd see reduce this effective range.</p>
<p>Another aspect to consider is that <a href="https://besjournals.onlinelibrary.wiley.com/doi/epdf/10.1111/2041-210X.13571" rel="nofollow noreferrer">increasing survey coverage</a> (sampling more of the landscape) can also increase the number of species detected, particularly when there is significant variation in habitat. On this point, more AM units could be deployed over a larger area than SM for the same price.</p>
<p>So, the fundamental question here might be: <em>fewer sampling points with greater individual range, or more sampling points with less</em>?</p>
<p><strong>2) Deployment time.</strong></p>
<p>Longer recording durations increase the number of species that are observed, and also reduce the cost and effort associated with servicing units to replace batteries.</p>
<p>With alkaline AA batteries, the AM <a href="https://www.openacousticdevices.info/support/device-support/how-long-on-average-do-batteries-last-from-your-experience" rel="nofollow noreferrer">may last 7-9 days</a> recording continuously at 48 kHz, and the SM Micro and Mini a similar duration, but <a href="https://www.wildlifeacoustics.com/products/song-meter-sm4-vs-mini-vs-micro" rel="nofollow noreferrer">listed at 24 kHz</a>. Lithium batteries could substantially extend deployment time for the AM and SM Mini units.</p>
<p><strong>A final thought</strong> –– if mixing different brands of sensors for data collection, what are the implications to control for during analysis?</p>
<p>What are your experiences with different ARUs? Do you have any suggestions for best practices when choosing equipment for a PAM kit? Thank you for sharing!</p>

<recording><pam><microphone><audiomoth><snr>
Song Meter vs AudioMoth PAM performance
# Song Meter vs AudioMoth PAM performance

(Asked by: username_0 on 2023-01-13)

I'm assembling a PAM field kit for the upcoming breeding season in the temperate rainforest ecoregion of Washington, USA, and would love to learn about your experiences with different ARU (Autonomous Recording Unit) performance.

My use case is continuous (up to 24 hr) multi-day monitoring of avian/insect species and soundscape analysis throughout a landscape with varying habitats, sample rate ranging from 32-48kHz.

I'm weighing the pros and cons of two common ARUs, the AudioMoth (AM) and the Wildlife Acoustics Song Meter (SM) series (with the SM Micro being the most directly comparable). As with any product, the fundamental tradeoff is quantity vs quality. I'm interested in two particular features:

**1) Detection range.**

Signal-to-noise ratio is perhaps the greatest factor determining detection range. Theoretically, every additional 6dB doubles the distance at which a signal can be detected.

SNR for the AudioMoth is [44 dB](https://www.openacousticdevices.info/audio), while Song Meters range from [73-80 dB](https://www.wildlifeacoustics.com/products/song-meter-sm4-vs-mini-vs-micro). SNR [has been found](https://peerj.com/articles/9955/) to increase detection space in the human-audible range by a factor of 1.7 when comparing a 55 to 80 dB SNR microphone. [Another study](https://besjournals.onlinelibrary.wiley.com/doi/epdf/10.1111/1365-2664.13229) pitting the performance of manual human detection of birds against ARUs found that a 72 dB SNR was roughly comparable.

[One evaluation](https://avianeco.com/wp-content/uploads/2022/12/White-Paper-AMSMTesting.pdf) in an open wetland environment saw the AM perform somewhat comparably to the SM4 within 100 meters in terms of detection vs distance, but with a difference of up to -13% of target stimuli captured from various biotic and abiotic signals. Certainly, the more dense the habitat vegetation the more attenuation we'd see reduce this effective range.

Another aspect to consider is that [increasing survey coverage](https://besjournals.onlinelibrary.wiley.com/doi/epdf/10.1111/2041-210X.13571) (sampling more of the landscape) can also increase the number of species detected, particularly when there is significant variation in habitat. On this point, more AM units could be deployed over a larger area than SM for the same price.

So, the fundamental question here might be: *fewer sampling points with greater individual range, or more sampling points with less*?

**2) Deployment time.**

Longer recording durations increase the number of species that are observed, and also reduce the cost and effort associated with servicing units to replace batteries.

With alkaline AA batteries, the AM [may last 7-9 days](https://www.openacousticdevices.info/support/device-support/how-long-on-average-do-batteries-last-from-your-experience) recording continuously at 48 kHz, and the SM Micro and Mini a similar duration, but [listed at 24 kHz](https://www.wildlifeacoustics.com/products/song-meter-sm4-vs-mini-vs-micro). Lithium batteries could substantially extend deployment time for the AM and SM Mini units.

**A final thought** –– if mixing different brands of sensors for data collection, what are the implications to control for during analysis?

What are your experiences with different ARUs? Do you have any suggestions for best practices when choosing equipment for a PAM kit? Thank you for sharing!

**Tags:** recording, pam, microphone, audiomoth, snr


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## 1 answers

### Answer by username_1 on 2023-01-14. Score: 1

As you wanted to monitor a rainforest ecosystem, which, I guess, lacks loud anthropogenic sound, you should use the system with the lowest system noise level (highest system SNR) to capture also quieter species. Only, if you restrict yourself to monitor loud fauna then you could accept higher system noise (lower system SNR).

> **Comments:**
> **username_0**: Certainly, if budget was not a factor, using the highest SNR equipment available would achieve the most quality recordings and largest effective detection range. But considering the vast range in price of different units (AM currently \$94, the SM series ranging from \$250-900) I think the cost-benefit analysis becomes worth considering.  For example, to monitor a single area of interest one could purchase 1x SM4 or 9x AudioMoth units for the same price. Despite significantly lower SNR, the more dense sampling of the AudioMoth units would result in an effectively larger detection range.  

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