iTunes “Sound Enhancer” Considered Harmful

I have now on two occasions, with two separate, quiet background, vocal-heavy songs, noticed significant and highly distracting audio artifacts introduced by the default “Sound Enhancer” on iTunes for Mac (specifically, iTunes 9.2.1 (5) on Mac OS X 10.6.4, on a Quad-Core Mac Pro with an embarrassingly large amount of RAM).  The two songs were “You make me feel so young” sung by Frank Sinatra (from “Songs for Swingin’ Lovers”) and “Do I love you?” sung by Peggy Lee (from “Beauty and the Beat!”).

Both of these problems occurred with CD-ripped highish-bitrate audio tracks (MP3 at 160kbps and AAC at 256kbps/VBR, respsectively).  I originally thought the problem was that iTunes was using a faulty MP3 decoder until I determined that the problem was for AAC as well.  What finally sealed it was using QuickTime Player to listen to the same file and discovering the noise artifact had disappeared.

Compare these two, which I digitally captured using Audio Hijack (trial version; buy it if you like it!):

Version with iTunes “Sound Enhancer” enabled:

Version played through Quicktime (no “Enhancer”):

(P.S., rightsholders don’t even think about flexing your DMCA at me.  These are 20-second audio quality demonstrations for nonprofit, educational and research purposes, and have no negative impact on market value of the works.  You are on notice that any DMCA abuses will be met with bad-faith treble-damage vengeance.)

Notice, on the second “Do I?” that the iTunes version has a big burst of static on the “I,” while the Quicktime version does not.  The artifact on “ young” is similar, on the “You and I” at 1:57, but I don’t have the time to capture and post that as well.

The morals of this story:

  • TURN OFF “Sound Enhancer” in preferences.  Just do it.  Not worth it.
  • Upgrade your headphones.  Never noticed this until I moved up to some better hardware.  It gets lost in the Apple earbuds.
  • Don’t trust that because a device/program/product has a big following that it does the right thing, at least from a quality perspective.  (Yes, I know, this should be self-evident to anyone who’s been awake since, say, the Industrial Revolution, or since the invention of mass brewing, but give me a break; I’ve been in the grips of Apple fanboydom since 2003 or so.)
  • Trust your ears, debug your equipment, and don’t put up with shit.  I didn’t believe for a good long time that the problem existed at all, much less that it could have been upstream from my headphones, until I debugged it.  Digital audio holds a promise for mankind, damn it, and you’ve got to make it live up to its potential.

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6 Responses to “iTunes “Sound Enhancer” Considered Harmful”

  1. LawlDawg101 says:

    Uh, that’s interesting because I have sound enhancer on my iTunes and it does add quality to the song. Although this may just be because I have a Logitech G35 Dolby 7.1 Surround Sound Headset. But as far as my headset goes I feel the surround sound is enhanced when sound enhancer is on and is lacking when it is off. But again, this just may be my high quality headphones speaking. Still I use it everyday and never turn it off, with me it does it’s job pretty well. I also saw a few things that it works only on crappy speakers. Well, I have a fairly new Creative speaker system and a $127.00 Logitech G35 Headset and it works fine. Anyways just putting my thoughts down.


  2. rlucas says:

    LawlDawg, thanks for the comment. I would venture a guess that the surround sound feature of your headset is what gives you different results. Most recordings are recorded in stereo, and so they don’t have separate 5.1 or 7.1 channels; the receiver (or in this case, iTunes) has to “guess” how to split up the sound. I’d bet that the sound enhancer is doing that for you, and guessing what signal should be on each channel, and as a result, you hear a “fuller” sound in your surround setup. (My home stereo receiver has a similar functionality.)

    The problem with such a functionality comes when you want to listen to the stereo recording in its sort of “natural habitat,” that is, with only the two channels (perhaps plus a subwoofer). You can’t get that with “enhancing” functions or “guesses” as to which signals to put on which channels.

    Try listening sometime with some strictly two-channel stereo headphones of good quality, and turn on or off the stereo enhancer. That should illustrate the issue.

  3. Josh says:

    Sound enhancer destroys the L+R feel. The illusion of the third speaker in the middle’s gone when it’s on.

    To comment on the surround part, I recently hooked my laptop up with my 5.1 surround sound system and with the enhancer on, I did notice that the speakers on the left and right and their respective rears (lol) do get more noise coming out of it but the middle speaker is left with the least ‘volume’ (?) Don’t know how to put it.

  4. The enhancer does miracles for dull & flat sounding 128 kbps tracks, and tracks ripped from old records, tapes and YouTube. in those cases, I prefer it to be wide open.

    However, harsh artifacts arise around the vocals of high bit-rate songs. In those cases I prefer the setting just a bit above neutral. It’s easy to adjust it just below the point the vocals go bad.

    So my main issue with the enhancer is, why can’t I adjust the setting separately for each song or each bit rate?

  5. Ryan says:

    In response to LawlDawg101 and his “high quality 7.1 Dolby Digital Headphones”. A couple things — I’ll never consider “Logitech” to be a “high quality” headphone – they are merely consumer-grade, entry level crap.

    And 7.1?? Let me take a look. You have two ears. I have two ears. My $1400 headphones that you won’t recognize the name of have two covers for said two ears. Unless you have 8 ears, what benefit does this 7.1 designation have other than prove that it works (you bought them). Your auditory systems have absolute no way of discerning anything but two channels of sound when they are affixed to your head. The only benefit that a “surround sound” system has is that your head makes small movements to track the sounds – in effect giving it surround sound. If these earphones are attached to your head (Which I hope they are!) you can’t detect these suttle differences in timing, frequency and intensity that your body uses to detect direction, other than right and left.

    My respect for rlucas for doing the research and knowing the difference between “nice sounding music” and of course the music that we were well intentioned to hear in the first place)

  6. rlucas says:

    Ryan, true if harsh medicine 😉

    One thing I’ll mention. It seems like Logitech bought up the M-Audio IE line of monitor headphones, and is rebranding them as “Ultimate Ears.” The M-Audio IE-(10,20,30) series were modestly priced but professional-quality monitors with isolation; perhaps not audiophile quality but very, very good for $100. I have kept my M-Audio drivers, although they’re now sporting UE cables and ear cups due to wear.

    If Logitech is still selling the same quality of stuff in their UE line, I’d vouch for those as being legitimate headphones.

    But yeah, LawlDawg101, the Logitech 7.1 headset and Sound Enhancer is probably not doing you any favors for faithful reproduction. That said, the Duke Ellington rule holds: if it sounds good, it is good. (Et a chacun son gout, as a corollary.)

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