[MLA] Fwd: iPhone limiting issue solved ? (Headphone safety)

[Bob Katz]

To complicate matters, European (and UK I think) phones are subject to 
the Cenelec legislation, which is up for revision. So I'm not sure if 
this applies to U.S. phones



Bob



On 3/30/22 6:31 AM, Ian Shepherd wrote:
>
> Hi All,
>
> I thought you might be interested to see this.
>
> Ian
>
>
>> Begin forwarded message:
>>
>> *From: *Ian Shepherd <ian at mastering-media.co.uk>
>> *Subject: **iPhone limiting issue solved ? (Headphone safety)*
>> *Date: *30 March 2022 at 11:30:15 BST
>> *To: *Buddy Judge <buddy at apple.com>
>>
>>
>> Hi Buddy,
>>
>> I emailed you recently about apparent limiting I was hearing & 
>> measuring on my iPhone when Sound Check was enabled, and I think I’ve 
>> got to the bottom of it. Apologies if this is something you’re 
>> already aware of, but it seems to be related to a setting that I 
>> didn’t previously know about:
>>
>> Sounds & Haptics > Headphone Safety > Reduce Loud Sounds
>>
>> In a nutshell, disabling this makes Sound Check behave as I would 
>> expect, ie. no limiting when enabled. It was enabled by default for 
>> me as a European user, and set to “85 decibels”. It seems that when 
>> this setting is enabled, the increase in level due to Sound Check is 
>> sufficient to trigger this safety limiting, resulting in aggressive 
>> dynamics attenuation. Specifically, the gain was reduced by over 4 dB 
>> on the classical piece I first noticed it with, which is highly 
>> audible and unfortunate.
>>
>> I realise that this behaviour isn’t a bug, it’s a feature. With Sound 
>> Check enabled, the music is lifted far enough to trigger the safety 
>> limiting. For classical you could argue that this is unavoidable, 
>> because of the wide dynamic range, but as I mentioned I’ve also heard 
>> and measured it when playing back Atmos mixes with Sound Check 
>> enabled, which is a much more mainstream use-case, and seems a shame.
>>
>> Having said all that, the main reason for this message is that in my 
>> testing the safety limiting is being triggered independently of the 
>> volume control. I’m not in the habit of listening super-loud on my 
>> phone, and even when I turn the playback volume way down, far below 
>> 85 dB even at the loudest moments, I’m hearing the aggressive volume 
>> reductions when Reduce Loud Sounds is enabled. In fact, I can hear it 
>> affecting the level simply by changing the threshold in settings, 
>> even with the volume only a few steps up from the minimum.
>>
>> This seems unnecessary, if its intentional. Shouldn’t the safety 
>> limiting be dependent on the actual playback level ? Otherwise it 
>> will affect the music even when the volume is low, and perhaps more 
>> importantly won’t necessarily protect users’ hearing when they choose 
>> to turn up the volume for loud music.
>>
>> Two Atmos mixes where the safety limiting kicks in when Sound Check 
>> is enabled are “Chandelier” by Sia and “Roar” by Katy Perry. The 
>> classical piece I’ve been using for testing is here:
>>
>> https://music.apple.com/gb/album/the-shepherds-carol/695609721?i=695610093
>>
>> The safety limiting is clearly audible at 1:30 to 1:40
>>
>> Again apologies if this is all something you’re already aware of!
>>
>> Cheers,
>>
>> Ian
>>
>>
>>
>>
>> ***
>> Ian Shepherd
>> Mastering Media Ltd <http://mastering-media.co.uk/> - Audio 
>> Mastering, Blu-ray and DVD Excellence
>> http://twitter.com/ianshepherd
>>
>> <http://twitter.com/ianshepherd>Mastering Media Ltd,
>> Kemp House, 152 City Road, London, EC1V 2NX
>> Registered in England and Wales
>> Company No. 073500450
>>
>> Tel. +44(0)1487 842498
>>
>
>
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-- 

If you want good sound on your album, come to Bob Katz 407-831-0233 
DIGITAL DOMAIN MASTERING STUDIO Author: *Mastering Audio* Digital Domain 
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