With sealed driver casings that help block out background noise, the EX71SL offers better sound isolation than vented models. However, if you want an even more effective barrier between your ears and the environment, consider Sony's, which employs active noise cancellation and has similar silicon pads.
We tested the EX71SL with both our MP3 player and our laptop by playing Outkast's CD, The Love Below. Featuring 100dB sensitivity, the headphones provided adequate volume and didn't easily distort when we cranked the music. On the "Love Hater" track's jazzy piano line and vocals, the EX71SL delivered slightly bright but not overemphasized treble. The song's deep electronic-bass line was reasonably present, proving that these earbuds supply considerably more bass than most of their kind, though plenty of portable over-the-ear models trump the EX71SL in this department. Some, such as Sony's MDR-G72, also sound airier and generally a little better, but the EX71SL does create a relatively three-dimensional sound field.
In the final analysis, the EX71SL's slick, comfy design and good sonics make it a solid choice for anybody looking for premium earbuds at a fairly reasonable price. Yes, there are better-sounding models, such as Shure's E3c, but those are considerably more expensive. If you can't afford them, this Sony is the next best thing.