Apple’s iPhone has an equalization feature that can help you optimize the phone’s audio playback for various music genres. You can also use EQ to compensate for differences between speakers, earbuds and headphones, getting the best sound quality from each. The iPhone has several EQ settings in its built-in Settings app, but you can also download more elaborate third-party graphic equalizers through the App Store.

How EQ Works

Generally, equalization divides the range of human hearing, about 20 Hz to 20,000 Hz, into a number of musically equal bands; the number of bands may vary from three to over a dozen, depending on the precision of the EQ device. Each band increases or decreases the response to sound depending on its setting: a “flat” or neutral EQ setting gives unaltered sound; the lowest bands cover bass frequencies, such as thunder, drums and bass instruments; the middle range covers most music and voice; and the highest bands cover the treble audio frequencies.

What EQ Affects

Most of the iPhone's EQ settings only affect the audio response of the Music app, and do not change the sound of video soundtracks, phone calls or alert tones. The one exception is the Late Night mode, which affects all the audio on the iPhone. The mode compresses the iPhone’s dynamic range, making loud sounds quieter and softer sounds somewhat louder; this prevents sudden, loud sounds from disturbing people nearby. Note that the Late Night mode is not available on iPhone 4 and earlier models.

Settings App

To change the EQ setting on your iPhone, tap the “Settings” app, scroll down to the selection for “Music,” and then tap it to display the Music settings screen. Tap the setting next to “EQ.” It may show “off” or one of the EQ modes may already be selected. Tapping the setting displays the list of available modes; these are prepackaged equalization settings named for musical genres. Although Apple has given the modes useful names such as “Classical” and “Jazz,” it pays to experiment with the settings to find the ones you prefer.

Third-Party Apps

Third-party EQ apps such as Equalizer, EQ 10 and EQu (see Resources) are full-featured graphic equalizers that give you more control over the iPhone’s simpler EQ settings. Instead of prepackaged EQ modes, these apps let you create your own by tweaking each audio band, and then saving the results. In addition to equalizer functions, some of these apps include effects such as delay and reverb.

Version Disclaimer

Information in this article applies to iPhones running iOS 7. It may vary slightly or significantly with other iOS versions.