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Loudness and frequencies response on popular smart phones

2019-08-02

Editor's note: If you've ever used different smart phones (especially iPhone and Android) to listen to music or play games, you may notice that the sound quality and loudness of the two is different. Does the difference have simple rules or characteristics to follow? This research aims to understand and share the design skills and strategies of audio of mobile games by testing the loudness and frequencies response on popular smart phones. Follow the audio journey with us and explore the mystery of sound on smart phones.

Author: Yang Jie, Senior Audio Designer of NExT Studios. He has been engaged in game audio design for more than 20 years and has extensive experience in various types of game audio design.

 

We always say different model of mobile sounds different. I'm working on mobile games for couple years. But never tried how they are different. And eventually, I got time to have the test:

  • The loudness on popular smart phones
  • The frequencies response on popular smart phones

1st of all, the "popular" mobiles are different in different places. The models I collected is almost the most recently popular devices in China. It won't tell you anything because of the hardware problem. But we can see the phenomenon some tricks from the test. The mobile phones for the test:

 

 

Also on the game side, different type of game sounds very different loudness because of the game play modes. So I collected 7 different mobile games and they are different game types. And they are very popular in Chinese mobile game market now. They are:

  • Fight the land lord
  • Happy cancellation
  • Arena of Valor
  • Clash Royale
  • Onmyoji
  • Homescape
  • PUBG (mobile version by Tencent)

(I actually tested 2 different versions of PUBG mobile by Tencent. Just for fun!)

 

 

The Testing Method

 

The Facilities:

  • Microphones:  Sanken CO-100(master) and Earthworks TC-20
  • AD:Apogee DUET FW
  • Mac Book Pro 15"
  • Senheisser HD25 AMP headphone
  • Signal A: Stereo white noise, PCM WAV, 60s long, generated in ProTools.  -11.9 LKFS, -8.1dBTP. This is the mastering signal.
  • Signal B: Stereo white noise, PCM WAV, 60s long, generated in ProTools.  -6 LKFS, -2.1dBTP (The target level is desined to 12LKFS)

The Steps:

  • Play the Signal A on the smart phones, with the original and default APP of each phone, at the max level of each.
  • Modify the microphone gain for each phone. Make sure the microphone input LKFS level is -11.9. So the -11.9LKFS is the target reference to each phone.
  • Play the games one by one and record directly into Pro Tools 12HD.

Specifications:

  • Reference Level: -11.9LKFS (-12LKFS)
  • Sliding Term: 30s
  • Recording time: over 5 minutes for each game

About the Speaker Box in mobile devices

  • a smart DSP handles the amp of DA
  • Temperature and Amplify detector feed the DA info back to DSP.
  • And then the DSP will execute the Auto Gain Control (AGC) to limit the output power and then protecting the hardware. The AGC works like a compressor with limiter.
  • Also, every manufactory can adjust and define the EQ and other in the DSP for getting different sound taste and response.

This is a research subject. It supposes to:

  • understand the loudness situation of the best sales mobiles
  • the loudness situation of currently best sales mobile games

 

 

 

The Loudness of speakers output, with White Noise

 

Reference: 30cm. -12LKFS white noise on iPhone 7P with -12LKFS target recording level.

 

 

Summary:

  • The content louder than -12LKFS doesn't sound louder. The inside auto-gain-control works in the devices just like a compressor.
  • The roll-off level between 30cm and 40cm is about 3dB. So the loudness loss is actually fast.
  • iPhone 7Plus doesn't sounds lighter, by white noise. And iPhone doesn't mean better dynamic. But the games on the iPhone is the quietest!
  • Vivo Y51A is the loudest one, by white noise. But the games on Oppo R9 is the loundest one. That's odd.
  • The loudest game is the AOV on Oppo R9, -14.8LKFS.
  • On the same distance, louder content over -12LKFS doesn't create louder sound. -12LKFS might be a physically critical parameter for most of phones. Actually -16LKFS is almost the max level to all the phones.
  • The same source, the loudness rolloff is quite obvious between 30 and 45cm.

 

 

So…

Any source louder than -16LKFS is meaningless and helpless even it's in short term. Only sharper sound can get louder perception sometime. But sharper sound means rude, hearing hurt and less patient.。

 

 

More charts for reference: 

 

 

 

The frequencies response on popular smart phones

 

 

The frequencies response on smart phones are really hard to simply explain it clearly by one article. And for lot of sound guys even it's probably not easy to read the spectrum properly. So, I think the PDF might be the better way that you can carefully read it in your free time.

Here as the introduction, I prefer to simply paste the conclusion for your reference: 

  • On all the devices, the most sensitive frequencies are: 220,500, 1k, 2.5k, 3.5k, 10k, 11k, 14k
  • All the devices, the speakers roll off from 1kHz. All the strong and rich games by hearing, the roll-off between 220-1000Hz are slower.
  • All the Android games start raising from 220Hz. But the iPhone 7P starts from 400Hz slowly. That's probably the reason of why iPhone 7P sounds lighter and softer, but more lower frequencies can be felt.
  • All the Android game stop high frequencies or roll off from 10kHz. iPhone 7P is quite same. But, it goes upper again from 16kHz to 22kHz.
  • Reduction around 11kHz, and the mean time slower roll-off above 11kHz, shall be good for getting smooth brightness. Please check Clash Royale and Homescape. PUBG can be another reference to prove it.
  • 4-5kHz shall be very careful band to be controlled and designed on all the devices.

 

 

In the 30 pages PDF, there are lot of details you can observe from the spectrums. I guess you can find more trick from the spectrums. Those spectrums can answer lot of questions like: does iPhone sounds better and why? And does Huawei phone sounds exploded? And what we can do for better sound balance to mobile games? ….

All the information above is just for your reference. Hopefully it can help.

Appreciate for the support from the audio team of NExT Studios. 

 

Have fun ❤❤

 

Click here to download the analysis data (3.42MB)

 

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