Audio Recording With a Smartphone

Audio Recording With a Smartphone


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:

  1. The built-in microphone(s).
  2. Using a microphone plugged in through the headset port.
  3. Using a microphone plugged in through the charging port.
  4. Via Bluetooth.

Smartphone with microphone

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: 1) the ability to 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.  The latest HTC phones include two microphones for recording in stereo, but most phones only have one microphone.

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.

A TRRS plug on the left, TRS on the right

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:

Diagram of OMTP and CTIA plugs

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.

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. 




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