frequency response compensation

All iDevices running iOS 5 have a built-in low cut filter for the built-in microphones and the headphone jack input.

This issue has been solved by Apple since iOS 6.

The reason for the low cut of the pre-iOS 6 devices is – as we believe – that they are designed mainly for recording and processing human speech. This high-pass represents a serious drawback for all kinds of frequency related measurements based on the use of the built-in microphone or the headphone jack. We gave this problem a lot of thoughts and decided to develop a compensation.

Please note: the compensation curves (offered as In-App purchases in the Analyzer and the Spectrograph) compensate for the corresponding device, microphone and (in the case of running iOS 5.x) the heavy low cut filter. In the latter case we are aware that the compensation pushes the noise in the low frequencies, but after much testing done by experienced sound engineers we are very happy with the results! Compensation curves are available for the built-in microphones (on Analyzer included), selected headsets and the i-series mics i436i456 and i266 from MicW. We offer the frequency responses as In-App Purchases. You can get them by visiting the store in the menu.

The compensation for the measurement microphone i436 from Mic-W includes a setting for the individual sensitivity given in the manual of each i436. In Germany, Switzerland and Austria all products from Mic-W are distributed by Synthax GmbH

If you are running our Apps on iOS 6 or later, the compensation curves linearize the frequency response of the corresponding microphones and devices.

Frequency responses of the iDevices running iOS 6 (measurement mode activated):

iPhone 5, iPad 2-4 headset-in frequency response



iPod Touch 4 frequency response

Here are the frequency responses of some external mics available for iDevices attached to the headset input:


The MicW i436 manual provides an individual sensitivity value. We integrated this as a setting in the i436 info page:

i436 help page

39 Responses to frequency response compensation

  • Wim donkers

    Replied on: 24/11/2011, 20:06

    The analize is looking good but is there also à tone generator , so i can check mij audio system, i dont no Where the mute switch is for, when its of the iPad is creaming, when ill juse a in/ out kabel or interface there is no scream or any sound, pink white or jou no.
    Is ther à manual to explane the differnt setting , it world realy be helpfull, Vrg Wim

    • dan

      Replied on: 27/11/2011, 23:48

      Hi Wim,
      the mute button mutes the output (speaker) – so if it’s on, you won’t have a chance for feedback. At the moment we do not provide a signal generator, though we may be adding it in the near future. For getting more infos how the Analyzer works and how to use it, check out the Analyzer product page. If those infos do not satisfy your needs, feel free to ask for support again, we will answer as quick as possible.

  • Larry

    Replied on: 06/12/2011, 12:26

    I’m sorry if I am leaving this comment for a second time. I cannot find my original question.

    How much does the in store purchase cost for the i436 compensation curve?

    Also, do you think that the Analyzer would help me in recording a classical guitar? Would I get a lot of noise in the low frequencies?



  • Sebastian Garreis

    Replied on: 09/01/2012, 18:07

    Hi there, I bought this app for use with the micW 436, in case I forgot my NTI Analizer. Now I miss a hold button in the analyzer window to do some EQ Settings without leaving pink noise on.
    Also a Leq measuring function with start/stop/pause buttons would be useful to work with average response values in different positions. Mostly used to measure and correct a speaker system in a venue.
    Thanks for your reply and best regards, Sebastian

    • dan

      Replied on: 10/01/2012, 10:11

      Hi Sebastian,
      we are already working on the Leq measurement and thinking about updating the hold function in the very next future. Thanx for your input!

  • Yoichi

    Replied on: 26/01/2012, 13:18

    I am using the application for some months.
    Then I noticed that there is a function of compensation.
    I’d like to buy built-in microphone bundle.
    Although, I pushed “buy” button in store, nothing happened.
    I tried several times. But no success.
    Please let me know how to buy it.

    • dan

      Replied on: 26/01/2012, 23:34

      Hi Yoichi,

      we had this problem before. This happens sometimes in the App Store – it’s an iTunes problem. Just try to be patient and try again later.

  • Tom Magyar

    Replied on: 15/02/2012, 13:17

    Hi! I’m using the App on 2 iOS devices. so i have to buy the frequenzeesponse for my micw twice or is it linken to my iTunes Account?
    thanx, Tom

    • dan

      Replied on: 15/02/2012, 13:23

      Hi Tom,
      if you have bought the frequency response compensations (or any in app purchase) you can install it on the 2nd device as well without paying. You just have to tell the iTunes Store that you want to purchase it (it asks “buy it?” and you have to say yes!) and after this iTunes tells you that you already bought it and it is available. This is rather confusing but that’s how iTunes handles this.


  • Corrado

    Replied on: 15/03/2012, 09:35

    I think you should able display rotation in the ipad relise : if you use an external micro like the micW 436, you will have it pluged in the righ side of the device.

    Corrado Fumis

    • dan

      Replied on: 02/04/2012, 12:28

      Hi Corrado,

      we are aware of this problem. We will address this problem in one of our next updates.


  • mst

    Replied on: 25/04/2012, 14:56


    I recently bought the Analyzer-iPad-App. Great! I also bought and paied the frequency response curve for the built in microphone. But unfortunately it does not appear in the section “frequency response compensation”. Why. What can I do?


    • dan

      Replied on: 29/05/2012, 13:31

      Hi mst,

      I replied to Sean and Gary already: we hopefully solved this issue! Apple has a “new” iPad2 for sale but they did not announce it. So we missed the new series and our App did not recognize it and could not load a compensation curve! We fixed this issue and the new Analyzer and Spectrograph versions are already in review process at iTunes. Hopefully in a few days they will be available and then you will be able to get your compensation curve!

      Thank you for your input and sorry for the trouble


  • Bob Brandherm

    Replied on: 26/04/2012, 16:52

    Just bought app and can’t find a way to print screen image of data. What am I missing?

    • dan

      Replied on: 27/04/2012, 08:55

      Hi Bob,

      the Analyzer does not offer the possibility to store data yet though we may be implementing it in a future release. Why do you think it does? Which part of our website suggests this to you? We will edit it to prevent further misunderstandings! The only way to get a screen image is to use the standard command (press home button and on button at the same time).


  • Sean Melvin

    Replied on: 30/04/2012, 18:23

    I bought the internal mic compensation bundle. I was charged for it but it doesn’t appear on my analyzer! What do I do because I need to start using this thing for work!

    • dan

      Replied on: 29/05/2012, 13:29

      Hi Sean,

      thanx to you and Gary we hopefully solved this issue. Apple has a “new” iPad2 for sale but they did not announce it. So we missed the new series and our App did not recognize it and could not load a compensation curve! We fixed this issue and the new Analyzer and Spectrograph versions are already in review process at iTunes. Hopefully in a few days they will be available and then you will be able to get your compensation curve!

      Thank you for your input and sorry for the trouble


  • Doug

    Replied on: 03/05/2012, 17:53

    Will you be creating calibration curves for USB microphones from Blue Microphones? I’m specificaly looking for a curve for their Snowball mic.


    • dan

      Replied on: 03/05/2012, 20:03

      Hi Doug,

      in the summer (hopefully July) we will release a major update for the Analyzer providing amongst other things full support for USB audio. If this release is done we will check out for which devices we will provide compensation curves – so I am afraid you will have to wait a bit longer for a definite answer – but this mic looks definitely interesting to us! 🙂


  • Steven

    Replied on: 07/05/2012, 18:11

    This is a great app guys. Thanks for developing. Just a quick question… I was using it at a live gig the other day and couldn’t seem to get readings much over 89dB SPL… And the gig was easily up over 100dB. Is there something I need to change here?

    • dan

      Replied on: 16/05/2012, 11:56

      Hi Steven,

      there are limits in the built-in microphone as well as a built-in limiter. We are compensating for this but at extreme values your device shows that it is not a qualified measurement instrument. Since iOS 5 there is a possibility to at least disable the limiter. We will integrate this “measurement mode” in our next major update. We decided not to do this immediately to give our customers some time – not everybody updates every few weeks. 🙂 This major update is scheduled for the summer and will provide some exciting new features!


  • Gary Shell

    Replied on: 24/05/2012, 07:38

    I just purchased the app and then the in-app purchase of the “Built in Microphone Calibration”. But When I touch the gear in the upper right corner of the RTA display, and then touch “Frequency response compensation” the app shows “No Frequency responses available” above the store and ? buttons. And “None” turn off, below them. if I now touch store, the “Built in Microphone calibration” option is no longer present in the list of purchasable options.

    What should I do now???


    • dan

      Replied on: 25/05/2012, 09:36

      Hi Gary,

      it would be great if you could tell us the device and iOS version you’re using…


  • Gary Shell

    Replied on: 25/05/2012, 23:02

    ipad2 running ios 5.1.1

    I just sent a detailed message with a timeline of what has transpired to your address.

  • Oleg Ivanov

    Replied on: 11/08/2012, 23:30

    Good Toy! Of course- ANALYZER not professional measurement instrument, but…may be- may be :)))

    • dan

      Replied on: 12/08/2012, 11:48

      It’s great that you like it! We are constantly improving the Analyzer – so may be one day…. 🙂


  • Tomi

    Replied on: 25/09/2012, 22:31

    Just bought the app, and the frequency graph definitely needs the zoom! Luckily you are promising this for the next update, I hope it will be published soon! Cause now I find it a bit useless on a small phone screen. It needs zooming in both amplitude and frequency axes. Then it will be great. For example making room measurements for digital room corrections I’m interested only in rather small frequencies and the dynamic range should be more like 20 dB, not 80 dB. Waiting for it!

  • Vlad

    Replied on: 01/11/2012, 16:42

    I’m planning to get a mic compensation curve
    for my iPhone 5. However iPhone 5 has three
    microphones, and I do not know which one
    you are using. Are the mic curves you’re
    offering for iPhone 4 and 4S compatible with
    iPhone 5 mic your product uses? I ask this
    because I didn’t see specific to iPhone 5 curves
    in your store.

    • dan

      Replied on: 03/11/2012, 13:26

      Hi Vlad,

      we don’t have a curve for iPhone5 (yet). Please be patient and don’t buy a curve until we release Analyzer 2.0 (hopefully within the next 2 weeks).

      Best regards


  • bob sheldon

    Replied on: 14/11/2012, 01:51

    you are only two steps from creating a nifty seismometer/vibration recorder. just need a lo cost geophone or transducer And some calibration….

    • dan

      Replied on: 14/11/2012, 07:55

      Hi Bob,

      thanx for the input… What features and specifications would you expect from such an App? How much would you be willing to pay for it?

  • Lucas Zwicker

    Replied on: 14/12/2012, 12:11

    Hey there,

    great application – I am really about to buy this one.
    But I am actually thinking about the external measurement mic thing.
    Will there be any frequency response compensation filters for mics like the NTI Audio Mini SPL?


    • dan

      Replied on: 13/01/2013, 12:30

      Hi Lucas,

      sorry for the late answer… but here it is: the NTI Mini is a mic we will not provide a compensation curve for – we concentrate on mics which can connected directly to the iDevices – sorr for this!


  • Ty Ford

    Replied on: 12/01/2013, 03:21


    I’m an audio engineer and blogger. I have an iPad 3 and Rode iXY mic. Will they work with your analyzer?


    ty ford

    • dan

      Replied on: 13/01/2013, 12:22

      Hi Ty,

      we did not try the iXY yet. But you can easily find out and help us too: just get our free SPL Meter APP dB Volume . If the iXY behaves like a normal class compliant USB device to the iPad and shows a level on dB Volume then the Analyzer will work fine as well. And: it would be great if you could tell us the results – we don’t have a chance to get our hands on an iXY yet here in Germany!!!


  • Gernot

    Replied on: 25/02/2013, 13:52

    I bought the app a week ago and it works really well. I also got me a MicW i436 which gives much better results than the built-in mic.

    However there is one effect which I cannot explain (and not really reproduce). Once I use the i436 it often happens that the spectra are shifted up a few octaves. I mean I sing a E (which has about 82 Hz) and normally I see a nice series of harmonics at 82/164/246 etc. Hz. But sometimes the spectrum appears much higher, at several hundreds Hz. Then I have to kill Analyzer. After a relaunch everything is fine again. This is mildly annoying so my question is what causes this behaviour?


    • dan

      Replied on: 26/02/2013, 13:35

      Hi Gernot,

      thanks for the input. We are investigating this issue and unfortunately we can not reproduce it. So it would be great if you could give us more details: the easiest way would be to make snapshots of the right and wrong behaviour and send them to us.



  • Logan

    Replied on: 22/05/2015, 08:21

    When using an external mic, such as the i436, does Analyzer compensate for the 200Hz hi-pass filter at the input level for iPad/iPhone devices?

    • dan

      Replied on: 26/05/2015, 17:12

      Yes. The Analyzer uses measurement mode, an iOS setting which provides linear frequency response on analog input (headset).

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