Bose SIE2i Review

Go for gold with a little help from Bose.

$149.95 MSRP
Buy now at Amazon
6.8 score Tested by Experts
  • The Bose SIE2i is better than 8% of the headphones we tested.
  • It is better than 11% of the headphones we have tested under $200.
  • It is better than 4% of the in-ear headphones we have tested.

Under the Hood

I tested a solid, balanced frequency response from the Bose SIE2i (MSRP $149.95), optimal levels of harmonic distortion, average channel tracking, and good overall impulse response. This product's only drawbacks stem from its design: Poor isolation and a somewhat high degree of leakage both owe to the earbud form factor.

Frequency Response

We test a speaker's frequency response from 20Hz to 20kHz to determine how much credence it lends to each audible pitch. These Bose perform well in this category—their frequency response somewhat resembles an equal-loudness contour (ELC), which equalizes the volume of all frequencies for the human ear.

Expect an ample foundation of sub-bass and bass notes, and a midrange that holds its own. There is a slight drop in volume between 2kHz and 4kHz, so that details throughout the high mids may be harder to distinguish at times. Largely, though, there are no drastic issues here—this is a fine test result.

The SIE2i tested with a balanced frequency response, giving decent emphasis across the entire frequency range.


Tracking refers to the balance between sound output for the right and left channels, or speakers. Headphones with poor tracking can have audible discrepancies in channel volume for particular frequencies, which can be both distracting and bad for your hearing. Fortunately, the SIE2i tested with no major tracking errors—no sudden shifts in emphasis over 2 dB in volume, which is practically perfect.

While imperfect, the SIE2i's channel tracking does not favor either the left or right channel too much.

Comparable Products

Before you buy the Bose SIE2i, take a look at these other headphones.


Attenuation is one area where the SIE2i are not the best of performers—and for obvious reasons. Attenuation refers to a set of headphones' ability to block, reduce, or dampen outside ambient noise. Obviously, a pair of active noise cancelers is going to do a much better job than these buds, which sit in the ear and block almost nothing of the sub-bass, bass, and midrange frequencies. They do, however, reduce some high midrange sounds to as much as one-quarter of their original volume.

The ear bud design means almost no noise is blocked out, though some high pitched sounds are reduced.


THD (or Total Harmonic Distortion) refers to the sum of electrical/mechanical audio interference a loudspeaker exhibits during playback. Typically, we like to see less than 3% total distortion, and fortunately the SIE2i tested within that acceptable range.

Users should note, however, that the maximum volume for distortion free playback is a little lower than usual for these ear buds—about 98 dB—but you shouldn't be listening to music louder than 100 dB for extended periods, anyway.

Despite the usual degree of distortion in the sub-bass range, the SIE2i's THD never totalled higher than the 3% threshold.

Other Tests

Impulse response refers to how long it takes the sounds emitted by a loudspeaker (or set of headphones) to fully decay or stop. The SIE2i tested well here, with no decay longer than 3.2 milliseconds.

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