It seems like smartphones will do anything. But do they make effective sound recorders? That depends on what you are looking (listening) for and what type of phone you have. Below I describe ways to record on your smartphone, with examples of products that might help. Most of this discussion is about Android phones and iPhones; tablets are for another day.
There are 4 basic ways to use your phone as a recorder:
- The built-in microphone(s).
- Using a microphone plugged in through the headset port.
- Using a microphone plugged in through the charging port.
- Via Bluetooth.
The built-in microphone
If you are looking to use your phone as a voice recorder, for recording personal notes, meetings, or impromptu sounds around you, then all you need is a recording app. I would highly recommend getting a third-party app, as the apps that come with the phone are pretty basic. Important things to look for in an app are the ability to: 1) adjust gain levels; 2) change sampling rates; 3) display the recording levels on the screen, so you can make any adjustments necessary; and, perhaps not as important, 4) save the files to multiple formats (at least .wav and .mp3). Also very handy is the ability to email the recording, or save it to cloud storage, such as Dropbox. Some of the most highly recommended apps for Android include Easy Voice Recorder Pro, RecForge Pro, Hi-Q mp3 Voice Recorder, Smart Voice Recorder, and Voice Pro. For iOS, Audio Memos, Recorder Plus and Quick Record appear to be good apps.
Microphones on various models of phones vary quite a bit. Newer phones have two or three microphones, but differ quite a bit in their sound recording abilities. Especially problematic seems to be recording loud sounds, such as concerts, although even those capabilities are improving.
External microphone through the headset port
Most iPhones and smart phones these days come with a TRRS port for the headphones. If your headphone jack has 3 lines (4 rings) on it, it’s a TRRS, which means it can act as a microphone as well as headphones. Before you attempt to connect an external microphone via the headset port, make sure it is a TRRS port.
Note the 3 (white) lines in the plug for the ear buds from my Samsung Galaxy S3, compared with the 2 (black) lines in the plug for a lavalier microphone. The color is irrelevant, but the number of lines is not.
Because of the differences in jacks, you cannot plug in any old microphone with a 3.5mm plug and expect it to work. Luckily, several manufacturers have developed microphones that plug right into the headphone jack.
However, there are also differences in the TRRS jacks, in the location of the ground and mic connections:
Differences in wiring between the OMTP (Sony, older Android) and CTIA (Apple, newer Android) plugs. CTIA is also called AJH. Note that there is only one mic input, so all input will be mono. Right and Left refer to headphone output.
This difference is something you need to be aware of, and make sure that any microphone, headset, or adapter is compatible with your phone. Unfortunately, there is no way to tell from the outside which is the proper jack for your device. However, the CTIA (Apple) version is becoming the norm, so Apple-compatible devices now work on many recent android phones. Be sure to check the descriptions to make sure your device is compatible. For more information on the wiring of various plugs, see here.
I have not used any of these, but I would expect them to be substantially better than the built-in microphone on the phone. You might want to review my page on “Choosing Microphones” if you don’t know the difference between a lav and a shotgun. See “Comparing recording on a smartphone to a dedicated recorder” for a video on how the iRig Mic Cast works on Android and iPhones.
If you already have a microphone with a 3.5mm jack or an XLR microphone (with power supplied – the phone can’t supply 48v phantom power), you can buy an adapter that allows you to plug it into the TRRS port. Make sure that the adapter is compatible with your phone. My Samsung Galaxy S3 is now using the Apple standard, so I need iPhone compatible adapters.
Note that this does not appear to work on all devices and microphones, apparently there are some differences in impedance levels of the microphones that the phones can’t deal with. [GEEK NOTE: TRRS jacks typically supply 1.5-2.5v, with 1.0-1.6KΩ impedance, which varies by phone model and manufacturer.] Some adapters are for microphones with batteries, and others specify microphones with no batteries. And Apple wiring is just a tiny bit different than the other CTIA (AJH) wiring. Some of these connectors also allow simultaneous monitoring if you plug ear buds or headphones into the other jack. This is very helpful in making sure you are recording what you want, otherwise you need to watch the visual input displays (if your app has them) or wait to play back the sounds. Even if you get the proper adapter, the microphone may not work properly with it. KV Connection carries a wide variety of connectors that appear to take different impedances into account; read the descriptions carefully. My advice, if you want to use a mic through the headphone port, is to get a mic designed for that use.
You also need an app that will allow you to select the external microphone. For iOS check out iRig Recorder, Recorder Plus, Rode Rec and Audio Tool. For Android, check out RecForge Pro, Tape Machine, Field Recorder, Smart Voice Recorder, or Audio Evolution Mobile. These are not all free apps, but reviewers say that the paid versions of the apps are worth it. Appcrawlr has put together a nice list of Android apps that work with external microphones, including several that allow video recording with an external mic. A new app, called Bat Detector, allows input through the TRRS port, USB (see below), as well as the internal microphones, and displays a nice spectrogram of the sounds being recorded. If you like to “see” what you are recording, check it out.
I recently tested a couple of different mics on a Samsung Galaxy S3 and an iPhone 5, and compared the results to a dedicated recorder. I describe the results here (well worth the read if you are contemplating adding a mic through the TRRS port). Also, one of my readers also tested a couple of different Android devices using a mic & mixer into the TRRS port, and posted a YouTube video here.
Note that the power to these microphones is pretty low, so they are probably not capable of recording quiet or distant sounds without adding a lot of microphone noise. The TRRS port allows only one microphone input, so the signal will be mono no matter what type of microphone is used. Some apps split the signal into two mono signals, but it will not be true stereo. It is not possible to get a stereo input through the TRRS port. Some companies (e.g., Saramonic) are selling fancy-looking setups with two mics that are supposed to be stereo, but there is only one input in the jack, so it is still a mono signal. They appear to function quite well in office and studio settings, but are probably not suitable for nature recording. A pre-amp, such as the Tascam iX2 would help, but is only for XLR mics. I would love to hear about any experiences using smartphones with external microphones.
Recording through the charging ports
There are fundamental differences between Apple and Android in how they handle recording through the charging ports. Basically, iOS includes audio support; Android does not. Google farmed audio support out to the device manufacturers, resulting in much confusion about which devices are compatible and which are not. For a discussion of the complexities, see this link.
External microphone plugged into the micro-USB port for Android
Some smartphones, including my Samsung Galaxy S3, come with a USB host, which means the mini-USB port (charging port) is capable of sending power. To check if your phone has a USB-host, either Google “USB host” and your phone make and model, or check GSMArena, and type in your phone make and model and check under “Comms.” If it has a USB host, it will be listed there (it will actually list “USB host”, not just “Micro USB”). You can also search “USB host” and it will list current phones with USB Hosting ability. There are also several apps in the play store that can check if your phone has a USB host (search for USB OTG). If you phone has a USB host, you can use a USB OTG adapter to plug in a USB mic (you must have the correct adapter). Again, this is low power, but is quite suitable for recording podcasts or narration overlays for video.
Below are some examples of USB microphones that reportedly work well:
It is also possible to plug in a USB audio interface, which greatly increases the options for adding multiple microphones, instruments, and MIDI devices. However, not all devices will support USB audio. According to the developers of Audio Evolution:
“Some Android devices have USB host but lack certain kernel features that are needed for USB audio. These are usually cheap ‘Chinese’ tablets, but also the Samsung Note 1 and Galaxy S2 lack it. When your device has a Rockchip cpu inside, chances are very high it will not work.”
In addition, some USB microphones and audio interfaces need more power than the phone can supply, and so may need a powered USB hub to function properly.
The Ultramic is a full-spectrum, ultrasonic USB mic that records from 0-200 kHz or 250 kHz depending on the model. It works well with Android phones with USB host capabilities, but is too noisy for general recording. For more about using the Ultramic to record ultrasounds, see “Options for recording ultrasounds.”
It is possible to plug a microphone with a 3.5 mm jack into the USB port, using something like an iMic 3.5 to USB adapter, or USB mixer with 3.5 mm mic inputs. I have tried this with a couple of different lavaliers, one powered, one not (mic to iMic to USB-OTG to phone). The signal was a little noisier than my dedicated recorder, but comparable to the TRRS port of the iPhone and much better than the Samsung’s TRRS port.
It is also possible to plug a professional mic into a smart phone, using something like the iRig Pro or the Blue Icicle (these convert an XLR to USB and provide phantom power). Some also include gain controls so you can control the level of the recording. I have not tried these setups, but there is information on the web about them. They primarily seem to be used for podcasts and studio work.
Note that for both adapters shown above, you are going from mic to usb adapter to USB-OTG to phone. That creates several potentially weak links in the chain and more places for problems.
Note: You cannot use a usb mic with the video recorder on the phone – it defaults to the onboard mics.
Software Issues for recording with USB on Android
The USB host is a digital input, and thus has better potential for quality input (including stereo) than the TRRS jack. However, the only Android apps I’ve been able to find that will record through the USB port are USB Audio Recorder (free), AudioFi ($5.99; demo available) and USB Audio Recorder Pro ($8.49; demo version available). In spite of the similar names, these are different products from different companies. They are very simple recorders. USB Audio Recorder and AudioFi simply record and saves the file with a time/date file name. USB Audio Recorder Pro also has a level meter and it allows you to set sampling rate and gain levels on some mics. It does not share files directly, but they can be shared (i.e., shipped to Dropbox) by going into the folders directly on the phone. Audio Evolution Mobile is a full-featured recording app that will use USB Audio Recorder Pro to accept USB microphones. But note the caveats above about compatibility issues with different Android devices.
Using the charging port of iPhones
Several manufacturers have developed microphones that plug into the power port of iPhones and iPads. If you want to record in stereo, this seems to be your best option. These microphones have helped turn iPads into miniature sound studios. Because different Apple devices have different configurations for their charging ports, make sure the mics are compatible with your device, although adapters may be available.
There are also converters available to allow 30-pin and lightning ports to accept USB devices, including microphones, mixes, preamps, MIDI devices, etc. A variety of apps are available for recording through the the power ports, including GarageBand, iPhone PC recorder, StudioMini, Rode Rec and others.
Recording via Bluetooth
Because most iPhones and Android devices are equipped with Bluetooth, which allows wireless connection between devices, they can receive signals from Bluetooth microphones. For this, you need a microphone capable of transmitting a Bluetooth signal and an app capable of receiving the signal. Most applications of this technology have been focused on the video industry, with most Bluetooth mics being lavaliers that allow wireless transmission of dialogue.
Examples of Bluetooth microphones that couple with iPhones and Android devices:
Apps that can receive the Bluetooth signals include Easy Voice Recorder for Android and Recorder Plus HD for iPad.
There appear to be a lot of problems with Bluetooth microphones connecting with smart phones, in terms of microphone and signal quality. It may be a little early for this technology yet.
What about Windows phones?
I don’t know anyone with a Windows phone, so I have been unable to do any testing. From examining the specs of some popular HTC, Nokia, and Huawei phones, they appear to use the CTIA standard for the TRRS port, but Nokias appear to have some conflicts with iPhone headsets, which may mean TRRS microphones may not work. None of the phones I checked had USB host capabilities, meaning USB recording option won’t work. But all of the phones had Bluetooth capabilities. So, sadly, it appears that if you have a Windows phone, you are limited to recording using the onboard mics or via Bluetooth. This site discusses apps for recording on Windows phones.
UPDATE (21 July 2014): According to reader Matt (see comments below), several models of Windows phones have TRRS ports that are compatible with iPhone-type microphones. He recommends the Rode Smart Lav.
Tips for recording with your smart phone
- Recording via USB is a better option than TRRS is your phone supports it.
- If you are connecting an external microphone, make sure the connectors are compatible with your phone.
- Watch your sound levels to make sure you are picking up enough sound, but not overwhelming the microphones.
- Simultaneously monitoring the recording helps get the recording levels within range.
- Getting close to the subject picks up the sound you want and minimizes background noise.
- Avoid windy situations and/or protect the microphones.
- Sound files can be large, depending upon your sampling rate, so make sure you have enough storage space.
- If sound recording is going to be an important use of your phone, consider an iPhone over an Android or Windows phone.
Smartphone or Dedicated Recorder?
Although smartphones are very convenient, for field recordists, they are not a replacement for a dedicated recorder. Dedicated recorders allow adjustment of gain and the ability to apply filters, and have more powerful pre-amps. They have more settings for recording, including setting the sampling and bit rate. And for nature recording, where you may want to set up your recorder and leave it record for a while – who wants to do that with their phone?
But if you use your phone for shooting video or for recording conversations, an external mic will be a great improvement over the on-board mics. For podcasting or recording quick conversations, a small microphone added to a smartphone would be convenient and adequate. Some of the microphones made for use with iPhones and via USB host are capable of recording in stereo; overall, iOS seems way ahead of Android when it comes to sound recording.
With the rapid gains in technology in smartphones, they may overtake recording they way they have overtaken photography. Now if they could just improve the quality of the sound in a phone call….
Last modified November 10, 2017.
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