iPhone audio super quiet

For some reason - my app's audio is super quiet on an iPhone. All good on the iPad and S开发者_如何学运维imulator and iPod Touch and even on another iPhone, but barely audible on one of the iPhones. The iPhone that plays that audio at the right level is running OS 4.3.2 (8H7). The iPhone that plays the audio extremely quietly is running OS 4.2.1 (8C148a) Any ideas?

Here's the code, though it's a device issue:

NSString *path = [[NSBundle mainBundle] pathForResource:sound ofType:@"caf"];
sounds = [[SoundEffect alloc] initWithContentsOfFile:path];
[sounds play];

In SoundEffect.h/.m is Copyright (C) 2010 Apple Inc. and I use it for audio playback in all my apps.

THANKS!

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Searching the net is showing that there is a bug in 4.2.1 on some devices, either plain sound very quite or not at all. Just upgrade to newer version or restore your iphone.