External Microphones for the App

[Jerry Bromenshenk]

External Microphones:

Microphones are a huge issue when it comes to this application as it based on sound waves. For one or a few hives, a smartphone's internal microphone should suffice. Be sure to put the microphone end of the smartphone or tablet into the hive entrance and slide it as far in as possible and still be able to push the start recording button when the bees settle down. For larger numbers of hives, you may wish to consider having one or more high quality, flat frequency response, microphones that can reach the approximate center underneath the cluster of bees in a hive.

Anyone with more than a few hives will want to use an external microphone, rather than having to slide the phone itself into the entrance of each hive.
In general, the microphone should be small, with good sensitivity, and a flat frequency response curve. The primary bee colony sounds are at low frequencies, although resonance frequencies may be important.

Two microphones that we recommend are:
Rode Smart Lav+ is a small, professional, lavalier condenser microphone, for iPhone and other smartphones.
Cost: $60-80 from box and internet stores.
Pros: Small, reasonably durable, 3.5 mm microphone jack, generally good quality sound
Cons: Cannot adjust recording gain; has a general, rather than microphone -specific, frequency response chart.

Tips:

1. Check that phone has a 3.5 microphone/headphone jack. Some phones and tablets may require a Rode SC4 3.5 mm TRS to TRRS microphone adapter and some of the newest phones require a 3.5 mm to USB-C adapter, ~ $10-$15.
2. Remove lapel clip, windscreen (bees chew on it), and attach the microphone to a thin wire (brass does not rust) to facilitate insertion into middle of hive via the entrance opening.

Dayton Audio EMM-6 Electret Measurement Microphone has a very flat frequency response. Each microphone has been calibrated. A measured response curve available, indexed by microphone serial number. Uses gold-plated XLR output connector.

Cost: $50-$80 from Parts Express Plus
Pros: Individual microphone testing and calibration offers better accuracy. Unit is metal, sturdy. This is a research-grade instrument, solidly built, XLR cables tend to be rugged.
Cons: Chunky, 3.5” x 0.47” (12mm) nose may not fit through shallow hive entrances. Requires a microphone interface like the IK Multi-media, iRig Pre XLR microphone interface for iOS and Android, ~ $40. However, with a 9-volt battery and adjustable gain, the iRig offers control over recording volume.

Tips:
1. XLR pre-amplifier must be switched on to 48 v Phantom power supply to the microphone.
2. Carry spare 9-volt battery.
3. Be sure to have an XLR cable, preferably long enough to lay the phone on cover of the hive when the microphone is in the hive entrance.
Sanitary Covers for Microphones

For those who elect to use an external, probe style microphone - don't use black foam covers - the bees will go nuts trying to sting the invader. For cleanup, I suggest when you see some gunk, use an alcohol wipe to gently clean - but be sure it tries fully before inserting into the hive - bees apparently don't like the smell. Obviously, it's desirable to have some form of disposable cover, especially if you move to other bee yards or your neighbor's bees or after sampling an AHB colony.

The best solution I can think of is to use an acoustically transparent fabric sock A common test involves attempting to blow through the fabric. If the fabric allows air to easily pass through, it will also allow sound to pass through, making it acceptable for use as an acoustic fabric. Soon as weather permits, I'm going to try paper KimWipes, maybe with a rubber band or bit of tape to hold a small piece over the end of the microphone.

[PHayesCT]

I currently have screened bottom boards on my two hives, and they are on a stand about 18 inches off the ground. If I were to take the audio samples from just under the screens (#8 hardware cloth) I can probably position the phone directly under the bottom center. Would that work as well or better than putting my phone directly in the entrance?

I am a beginner beekeeper in 2019. I've been through training classes, workshops and books, but still recognizing what to look for when I open the hives.

Thanks

[Jerry Bromenshenk]

You will have to experiment, our tests and tuning have been mainly aimed at standard equipment with solid bottom boards. Please add a note to your reports indicating that your hives have screened bottom boards. Clearly, a microphone near an open hive bottom is going to pick up more sound interference from nearby equipment, planes flying overhead, etc.

[PHayesCT]

I tried Bee Health Guru for the first time on my 2 hives yesterday. I used a Smart Lav+ connected to my Google Pixel XL 2, placing the microphone without the foam cover on the end of a thin fiberglass rod so I could get it in through the entrance and in the middle of the hive over the bottom board. Here's how things went for me:

* The app occasionally closes itself before "Thank you for joining..." screen. I would say about 30% of the time.
* On at least one scan, the green sound meter under the bullseye button would not register upon starting the sample (although it was registering just before hitting the button). I re-scanned and it worked fine.
* It seemed although the scan level was registering, it was lower than the "ideal" level. But I don't think there's any output to indicate how good a scan it took. With the microphone positioned as I had it, I can't do much better.
* I forgot to hit the 60 second sample instead of the 30 second default. Next time I'll remember to do the 60 second.
* My 2 hives are total different. The first one has been troublesome, is small and queenless. The second one is two very active deep hives full of bees and an active laying queen (lots of new eggs). The report on the first hive actually was 'No' for queenless with 5.0%, the second 'No' and 4.5%.
* The results were scanned and uploaded a sample from both hives. Hopefully you received them.

[Jerry Bromenshenk]

Thank you for the feedback. The sound delay is unique to Android, it's sounded activated. You are asked to wait a bit before recording, both to ensure that the app is picking up the sound, and more importantly, to ensure that the bees have settled down, aren't stinging the phone, etc.
The hiccups occur if you've an older, slow phone; but more often than not, it means you've got apps open. Before using the app, close all other apps; and if you haven't cleared your memory cache recently, we suggest that you re-boot your phone. The queenless analysis error, and the queenright correct are important data points for tuning. Thank you for the scans, feedback, and uploads.

[[email protected]]

I'm using a samsung tablet SM-T390 with the Rode lav+ mic taped to a piece of wooden molding (1/8"x1/2") long enough to allow me to position the mic near he center of my 8 frame hives. The first few hives I did not use the foam cover on the mic but then became concerned that honey or propolis would plug the mic so I added the foam cover. for all subsequent scans. I've submitted about 20 so far.

My elder brother (I'm 75)came to visit yesterday. Prioir to the collapse of the Soviet Union he spent 20 years as an independent contractor with the Office of Naval Research extracting and analyzing data from acoustic files collected from underwater listening stations. Later he was a consultant for a medical device manufacturer of a heart valve diagnostic device utilizing acoustic data.

He wanted to hear the raw acoustic data collected in a scan so we located the wav file of my last not yet submitted report. He expressed concern that my taping the mic to a wooden stick and/or my use of the foam cover might in some way disturb the file. Could you locate a recent scan from me and advise if the data seems ok?

[Jerry Bromenshenk]

We can't tell anything by looking at a file, but it's good to know. However, removing the foam cover is important - bees chew on it, which adds spurious noises, and we prefer that the microphone be mounted on something small, like a stiff wire with a bit of upward bend to aim microphone slightly up - fewer bees disturbed when inserting and fewer hanging the wire/stick when pulling out.

Pushing the microphone into the center of the hive is intended to help avoid sounds like lawnmowers in the distance.

[Kenclogger]

I did try first using the built in Mic on my IOS Xs max phone and then with a wired less expensive mic and got the results in the image of a spreadsheet I am attaching. Given the results below with hardly anything approaching 50%, I basically have no usable data even though during the recording the meter was showing the volume was bouncing into the proper range. So in order to get data that can be used I need to get a dayton mic with the xlr pre amp cable. Is that correct or am I interpreting my results incorrectly? I am hesitant to spend the $60 for a mic and another $40 for the XLR cable with preamp if I don't have to.

[Jerry Bromenshenk]

Unless you know that you've problems in your hives, none of these results show any significant problem. If you inspected, found problems, after recording, and you sent us the data, then we can use it for tuning. If you didn't find any problems, which I assume are the none's, then the app is doing exactly what it should.