[oskar]

Any comments on the accuracy of the many SPL meters for iphone?
Thanks

[mresseguie]

Excellent question. I just switched from a Samsung phone  to a 6-plus, so I'd like to know which meters work better.

Michael

[Phil A]

The weak link is the microphone.  You can buy the Audio Tools App and a microphone and it will be better.

[Phil A]

Here's a microphone - http://www.parts-express.com/dayton-audio-imm-6-calibrated-measurement-microphone-for-iphone-ipad-tablet-and-android--390-810

[Phil A]

It depends on how often and how serious you are when you use it.  I have the above microphone and that's fine for me.  You can spend much more on an SPL meter - for example -

http://audio-video-supply.markertek.com/search?w=spl+meter&sitepref=1

[Phil A]

This is the Audio Tools App - https://itunes.apple.com/us/app/audiotools/id325307477?mt=8

[oskar]

Well do you think with built in mic accuracy could be  +-1dB.?
Just trying to get a sense of general levels .

[JohnR]

+/- 1 dB would be unrealistic I think. For that, you'll need to buy a properly calibrated meter. Maybe expect +/-5 dB. (Could be optimistic.)

[Phil A]

Here's one general article - http://www.higheredtechdecisions.com/article/pro_usb_attachments_for_precise_mobile_audio_measurements

I'd pretty much agree with what John said.  Even the old Radio Shack analog meter (and I still have one) had a microphone that wasn't what I would call all that great had deficiencies.  Rivesaudio.com sells a test disc (I think for $18) that is made to compensate for the deficiencies in the Radio Shack analog meter.

[Phil A]

Here are a couple of resources/articles for general info:

http://www.prosoundweb.com/article/print/sound_level_meters_the_primer_what_how_why_techniques_more

http://www.tnt-audio.com/clinica/spl-meter_e.html


Keep in mind what the microphone is designed for in the iPhone.

[oskar]

+- 5db? If thats the case then it's virtually useless.
I'll try and compare it with a proper meter and report back.

[JohnR]

OK... What "proper meter" would that be?

[Phil A]

Here's another article - http://blog.faberacoustical.com/2009/ios/iphone/iphone-microphone-frequency-response-comparison/

"
Not surprisingly, none of the iPhone models rivals a lab-grade sound level meter with its built-in microphone, but either of the 3G models can potentially give you a decent ball-park estimate of the current sound level, although the low frequencies will be de-emphasized.....   It may be important to keep in mind that the goal, here, is to see what makes sense in terms of using iPhone OS devices as inexpensive, portable sound level and spectrum analysis tools."

Here is one resource on the Radio Shack SPL meter (which I have and also have a 1/3 Octave Audio Control RTA) - http://www.hometheatrebasics.com/home-theatre-tools/radio-shack-meter-correction-chart/   So even the cheaper SPL Meters have deficiencies.  If you goal is noise in the workplace, they may not make all that difference.  If your goal is acoustic measurement of your audio system, they have deficiencies.

[oskar]

OK... What "proper meter" would that be?

Good question. I see there's an adapter available to connect any external mic to the phone.
I was doubtful whether the built in mic could handle the low frequencies.

[Phil A]

Good question. I see there's an adapter available to connect any external mic to the phone.
I was doubtful whether the built in mic could handle the low frequencies.

The external microphone at Parts Express is what I have and posted earlier in the thread.  I also have an iPhone 4, 5 and 6 (use the old ones for things like the Oppo Media App or JRemote for the music server) and have had more than one of the Apps on each of them (in addition to the RTA App). 

[JohnR]

OK, there are two (roughly) issues here. One is whether the frequency response is accurate, which (if it isn't) will throw off the SPL figure that is integrated over all frequencies. The other is the degree of accuracy to which the measurement software knows how SPL is converted into the numeric (internal) level that it actually reads. You can't get +/- 1 dB unless the specific microphone has been calibrated against a known reference. Even if the software knows the average of some particular microphone model (or phone etc), it doesn't know the figure for your exact microphone.

[oskar]

Yes that makes complete sense John.
With my, ahem, doggy iphone meter it shows my listening levels are around 85db with c-weighting.
Not crazy loud but not conversational level.