iPhone Speaker Audio (compressed, limited, distorted)

[infinitesymphony]

Sometimes I like the ultra-band-passed effect of listening to music on my phone's built-in speakers. It seems less distracting that way if I'm trying to focus on something else. So, I end up using the phone's speakers for a decent chunk of time every day.

I recently upgraded from an aging iPhone SE 2016 to a slightly larger but much newer and faster iPhone 12 Mini. There's a lot to love about it and it even has stereo speakers.

However, the speakers make music sound so, so bad at all levels. I've noticed for a long time on iOS devices that after you get to around two volume levels away from max, those last two notches seem to be adding increasingly heavy limiting to the sound. This decision makes sense to me from a practical standpoint because it's a way to get a lot more average volume without asking the speakers for much more excursion.

On this new phone, it sounds like heavy limiting and/or multiband compression is engaged at all volume levels. It's very in-your-face and exceptionally bright. With the stereo speakers oriented correctly toward my ears, I get an out-of-phase sensation like heavy Dolby surround processing is being applied to everything.

Snare drums in particular have a strange downward "pew" doppler effect like a synth laser beam patch. I'm not sure how else to describe it, but maybe I can record it.

The average phone user appears to have noticed this effect and describes it as "tinny," "echoey," or "distorted" sound.

Anyway, thanks for listening to my rant. Please chime in if you've noticed something similar.

 

[ansonx10]

I know it's an old post, but this is one of my favorite topics.

You're right about the multiband compression happening much more strongly at the top of the volume slider. Apple also does some per-device-model tuning as well, and they may have messed it up on the 12 mini. (I don't have one so I can't directly say.)

I know this was over 3 years ago, but I'd tell you to check the EQ settings (in Settings on the stock Music app's page.) Normally those EQs only apply to the stock music app, but there is one exception: the "Late Night" preset. That applies additional compression and EQ to ALL audio on the phone. It reduces bass and compresses audio starting at a much lower threshold. I'm not sure if it's just modifying the existing audio processing, or adding an entirely new chain. (Probably the latter, given how it sounds and how Apple tends to do things.) The result is far more compression and high frequency sound than normal.

The downward "pew" sound is a result of phase dispersion, caused by the steep filters used in some multiband compressors. (There are other ways to do it that don't have this problem.) Basically the lower frequencies are delayed in their phase, causing short sounds to audibly slide down the spectrum.

As far as other sources of distortion, I've noticed if speaker grilles are too small/dense, or get clogged with junk, the wind being forced through them by lower frequencies will cause audible "chuffing" noise.

I would be overjoyed if we could tune all the audio processing parameters ourselves, because I'm not crazy about many of Apple's choices. But even if Jailbroken, no one has created a way to do so. It would probably be possible by playing with the .plist files, but IIRC they're a bit too complex to set by hand. (Especially considering that changes aren't reflected immediately.) They seem to be using Apple-created audio units that aren't even available on macOS, and I'm kinda jealous.

 

[Petrushka]

Contrarian point of view:

Phone speakers distort sound in a way that makes it possible for me to understand speech without hearing aids.