'In-ear' headphones, or earphones, have small earpieces that fit in the ear just like earplugs and offer good environmental noise blocking typically superior to over-the-ear headphones. In-ears are convenient, many deliver superb audio quality, and in-ears are also very unobtrusive, making them a popular model for mobile smartphone users. The DENON AH-C260R is an iPhone earbud replacement offering quite good sonics at a wallet-friendly price.
The great NOCS series of in-ears are expressly made for various types of smartphones and all offer killer sound quality and full telephony. The Klipsch Reference S4i is a very good-performing and comfortable in-ear stereo headset that will have you listening to music and making iPhone calls with a clean voice tone and great ambient isolation at a reasonable price. Listeners needing killer sound plus sweet looks will love the awesomely cool Woodees Vintage w/ Mic. Etymotic Research is an original patent-holder in the world of in-ear audio and the highly focused musical presentation of their top-level Etymotic HF3 is extra crystal-clear in the mids/highs, and the intelligibility of the mic is second to none; the HF3 is certain to please audiophile iPhone/iPad listeners seeking max detail clarity with tightly controlled bass.