All music is based on sound frequencies. Live musical instruments and voices make sound frequencies that travel directly through the air to your ears. Recorded music works similarly: sounds are captured and converted into data, then your iPod or stereo converts the data back into sound frequencies, vibrating your speakers or the miniature speakers in your earbuds at frequencies resembling the original sounds.
Because of limitations in recording and playback technologies, recorded songs will never sound precisely the same as the originals: the quality of a recording, your playback equipment, and where you listen to the music will affect the sound. This is where equalizers come in. With the aid of iTunes and/or your iPod, you can make temporary adjustments to the sound frequencies you hear, correcting or reducing flaws in recording and playback hardware.
What is the iTunes Equalizer?
Though many people don’t realize it’s there, iTunes includes a built-in, highly adjustable equalizer that lets you make tweaks to ten different sound frequencies. You can access this equalizer by clicking the Equalizer button at the bottom right of the iTunes window.
The equalizer window contains a checkbox to turn it on or off, a menu to choose and edit equalizer presets, a “Preamp” slider and ten frequency band sliders. If you don’t turn the equalizer on, your music will sound as good (or bad) as the compressed file that’s sitting on your computer. However, if you do turn it on, you can punch up (or downplay) individual sound elements in any song.
How iTunes’ Equalizer Works
The first slider you’ll see is the Preamp slider, which is a general volume booster and reducer. You’re probably better off leaving this as is and correcting the volume through your stereo or other playback device.
Each of iTunes’ ten frequency band sliders actually affects a range of frequencies around the numbered (32/64/125/etc.)frequency. Other programs’ equalizers may have more or fewer bands; the choice is somewhat arbitrary, but in all cases these frequency bands correspond to different types of sounds. Within iTunes, you can group these ten bands into three main types of sounds:
Bass: Skipping the Preamp, this can be found in the first two sliders: 32 and 64 Hz. These frequencies cover the lowest notes; in many cases, you won’t hear these bass sounds with your speakers – especially if you use basic computer speakers without a sub-woofer. Increasing these bands gives more depth to bass-heavy music, such as dance music, reggae, and rap.
Midrange: The midranges are the next six sliders from 125 Hz to 4K Hz, and are where the majority of audible sound in music actually takes place. This is where the voices are, for example, and where the guitars, pianos, drums and most other instruments reside. A piano’s middle C is about 278 Hz. There’s still some bass at the low end (125 Hz) of this range.
Treble: The last two sliders, 8K Hz to 16 K Hz, affect the high, treble sounds. While most music tends to sit in the midranges, the trebles hold both the very high ends of many instruments, such as violins, cymbals and even high voices, but also contain very important harmonics, or sounds that are multiples of the frequencies of basic tones. Harmonics give music a great deal of depth; if you cut these frequencies off, you’ll notice that the music sounds “empty.” Harmonics are always above tones; for this reason, the treble sounds are arguably more important than the bass sounds, even though bass receives a lot more attention.
Adjusting the Equalizer
To use the equalizer’s basic functions, you can simply check the On box and select a preset from the popup menu. Apple includes names such as Bass Booster, Treble Reducer and Small Speakers, which affect specific frequencies to make up for deficiencies in specific types of speakers or headphones; others, such as Acoustic, Classical and Electronic heighten the main frequencies used by these types of music. You can also select Manual from the popup menu to drag the sliders and create your own settings.
While the first group of settings is useful, and these presets are clearly labeled, the second group is less clear; all they do is increase or decrease the volumes of certain frequencies to make them stand out more. If you look at the Rock settings, you’ll see that bass and treble are increased, while mid-range frequencies are barely affected (if at all).
If you want to try out the equalizer, start by picking some of your favorite music – songs that you’re most familiar with. Listen to a track with the equalizer off, then turn it on, trying out different presets to see if it sounds better. Try listening through different speakers to hear the difference; one of the most effective ways to use the equalizer is to use the Bass Booster preset with small computer speakers that don’t have a sub-woofer. Or you could use the Bass Reducer setting on some portable speakers that sound too deep. Try listening to different headphones, in different locations as well, to see how the music sounds when there is ambient noise. Most earbuds benefit from a boost in the low frequencies.
As people age, our ears start giving out at the higher frequencies. If you know that you have some hearing impairment, raising the 4K, 8K and 16K bands slightly may make music sound much better to you.
Creating Your Own Presets
If you start adjusting any of the sliders on the equalizer window, the popup menu displays Manual. You can make any adjustments you want to the different sliders, using the general guidelines for bass, treble, and midrange adjustments above. After you have done this, click the popup menu and select Make Preset, enter a name for your preset, then click OK.
You can then select your preset from the preset menu, and apply it whenever you want. To rename or delete a preset, select Edit Menu, then select the preset you want to rename or delete and click one of the buttons.
If you delete a preset, iTunes asks if you want to remove it from all songs for which you have set it. (You’ll see below how to apply presets to specific songs.)
When you use the equalizer in this manner, simply turning it on within iTunes and not setting individual songs to use specific presets, then all songs will use the same equalizer settings you’ve created.
Applying Presets to Individual Songs
Once you start fiddling with the equalizer, you’ll quickly realize that there is no one-size-fits-all solution. Different songs use different instruments and frequencies, and the changes you make to one song’s sound will have a very different impact on another song’s overall sound. One song may benefit from increased bass, while another may sound muddy. Boosting the treble may help some instruments, but it will make cymbals and other high-pitched instruments sound tinny.
With this in mind, you can apply equalizer presets to individual songs, or to entire albums, as you wish. One way to do this is to select a song, then select File > Get Info. Click the Options tab, then select a preset from the Equalizer Preset menu.
To apply the same preset to multiple songs, select several songs, then select File > Get Info. Then select a preset from the Equalizer Preset menu.
Finally, if you choose Edit > View Options, then check Equalizer, a column displays showing a popup menu from which you can select equalizer presets. This column shows which presets you have applied, or remains blank for the songs for which you have not selected presets.
Using the iPod’s Equalizer
The iPod has a stripped down version of the iTunes equalizer – basically just the preset titles, without the ability to individually alter any of the ten individual bands. You can access the iPod’s equalizer by selecting Settings from the iPod’s main menu, then EQ. To select an equalizer setting, just scroll to find the one you want to use, then press the Select button on your iPod. The specific equalizer setting you pick will affect all songs on your iPod, except as noted below. To turn off the equalizer, select Off.
One bummer: when you create custom presets on iTunes, they don’t get transferred to the iPod – you can only use them within iTunes. However, if you apply Apple’s original presets to individual songs from within iTunes, these presets will override any across-the-board equalizer setting you have picked on your iPod. For example, if you use iTunes to set a specific song to use Bass Reducer, then choose the Bass Booster preset on the iPod, the song will still play back using Bass Reducer.
Other Sound Features: Crossfade Playback, Sound Enhancer and Sound Check
iTunes also offers three additional options that let you enhance your music. To access these settings, click the Audio icon in the iTunes preferences.
Crossfade Playback lets you gently segue songs from one into another, fading one out as another fades in. Check this box, then choose a number of seconds for the fading segue. Note that you won’t hear any crossfade when a song ends or begins with a few seconds of silence (unless you set this slider to a greater number of seconds).
Sound Enhancer is an artificial surround sound feature. Check this box, then try moving the slider to different settings. You can hear this best when listening to headphones; depending on the music you listen to, toggling it between on and off results in a very clear difference, an echo that creates the impression of greater depth. If you like this sound, move the slider to adjust the amount of enhancement.
Sound Check is designed to play back all your songs at the same volume, regardless of the disparate volume levels at which they were recorded. When you check this box for the first time, iTunes analyzes your music and determines whether each song has to be played louder or softer. Then it records a setting for each song, in decibels, for the volume adjustment. However, it’s not a perfect process: iTunes analyzes entire tracks, so you may find that a mellow song that ends with a crescendo is far too loud at the end, and the following song sounds too low. You can turn on a similar setting on your iPod: select Settings > Sound Check, then press the Select button to turn it on. This only works on the iPod if you have it turned on for iTunes; the iPod gets its Sound Check information from iTunes’ analysis of your music.