Is S2 really needed ?

[Stephen]

Hi

I have "tested" this project with 5 people aged 70+ and they can all hear the higher frequency
(  suitable ear protection was used ) this has caused me to wonder if the lower frequency generated by S2 is actually needed.

Could be I am missing something, if so I am sure you guys can help me out.

Regards to all.

Stephen

[Steve Gibson]

Hi Stephen!

What I'm wondering is what the tweeter's frequency is?

Do you have a smartphone?  And if so... is there a free frequency metering app that you might use to get a frequency reading?

/Steve.

[Tom F]

..

[Tom F]

Hi Steve (et al)-

My results of v2.2.2 were disappointing in terms of volume, especially given the dangerously loud warnings, after two builds. Reading Sigpoggy's info on sound pressure made me wonder if my Galaxy S3 would give me similar results. 

Using an app called Sound Meter by Smart Tools Co., my results were in the -50db range. Disclaimer-- I was indoors, not at a properly measured distance, had not calibrated at all, and most importantly, barely have any idea what I am talking about.

Several questions come to mind. Are the microphones and audio circuits in cell phones able to respond at the frequencies we are looking at? Does the volume control matter? How can the results on  phones (OS vs. OS, Mfg. vs. Mfg, model vs. model, and even individual handset vs. handset), and apps be compared?

Thanks for all of the education provided by this project.

-Tom

[Steve Gibson]

Tom (et al)...

I'm SERIOUSLY looking into establishing some uniformity of measurements around the Apple iPhone.  I KNOW (well) that's not what everyone owns.  But perhaps everyone knows someone who has one.  The app Jim (Sigpoggy) uses is free.  There are some prettier ones, but I do think that free is important.

Anyway... as part of my research, I found this VERY ENCOURAGING page:

http://blog.faberacoustical.com/2010/ios/iphone/iphone-4-audio-and-frequency-response-limitations/

And compared to older phones:

http://blog.faberacoustical.com/2009/ios/iphone/iphone-microphone-frequency-response-comparison/

/Steve.

[Stephen]

Hi Steve

Using Frequency Meter PRO on my Nexus 7 I have a reading of just 1397Hz....way low for what we need !
Regards Stephen

[Tom F]

Those graphics make it look as though the newer i-devices are all using the same audio mic and electronics, and the similarity of the three curves leads me to think that each individual device might track. Using an (original) iPhone looks fairly useless in the 15KHz range.

It could also offer a reliability check to run tests using several devices for those entrenched in the Apple ecosystem. However I am not so entrenched and I'm probably not the only one. So, I am hoping that someone straddling the ios and Android worlds might do, and post, some comparisons.

-Tom

On Monday, January 21, 2013 3:35:32 AM UTC-8, Stephen wrote:

[Steve Gibson]

Ah!

Using Frequency Meter PRO on my Nexus 7 I have a reading of just 1397Hz....way low for what we need !

Yes yes yes.  That implies that LOTS is wrong.  But it DOES explain why your collection of 70+ friends were all able to hear it clearly.  So that mystery is solved.  :)

/Steve.

[Stephen]

BTW another app tells me the decibel reading is 115 dB. My hearing is as good as my young son so 115 dB has to be wrong.

[Kindanyume]

https://play.google.com/store/apps/details?id=com.julian.apps.AudioTool&feature=search_result

I have not tried this yet.. but it's highly rated and should be a good
alternative as well for those of us using Android :)

[Kindanyume]

Note.. it's sadly not free though :(

[Steve Gibson]

BTW another app tells me the decibel reading is 115 dB. My hearing is as good as my young son so 115 dB has to be wrong.

Yeah.  115 dB would blast you out the back door!

/Steve.

[sigpoggy]

One upside to this app is you can calibrate it for different frequencies. The downside to all these apps is you have to calibrate them if you want something better than ball park. I don't know an easy and cheap way to calibrate them.

I experimented with 5 different iOS devices (iphone 4s, itouch 4, itouch 5, ipad 1, ipad 3) all using the Decibel 10th app...

1. you need to know where the mic is for the device: iphone and itouch 4 - bottom edge; ipad1 top edge, ipad 2 top edge at 45 degree angle; itouch 5 back side next to camera.

2. itouch 4 read 10 db higher for typical back ground noise than all the others. The other were within 4 db of each other.

3. at 8khz, they were pretty much in sync. (adjusting the itouch 4 to match the others)

4. the itouch 4 and ipad 1 had lower readings( more than 10 db) than the three newer devices for 16khz. The three newer devices were fairly close, the ipad 3 read a little lower (about 4 db) at 16khz than the others. 

5. When you calibrate, it changes the max level. I tweaked the itouch 4 to match the others and it pegged at a lower level - 93 db.

6. My assumption is these apps are optimized for the iphone and probably in many cases are not even tested on other devices unless the app is targeted for ipad. I also assume this app does not discover the current device and compensate for its characteristics, hence the roll off at higher frequencies.