Instruction: Answer the given question by extracting information from the supporting document.

Input:
Question: Do the S4i have active or passive external noise canceling?  I want something that will eliminate echo and background noise into the mic.
Document: I needed to replace my 5 year old sound isolating Shure's but didn't want to pay more than $100. I need sound isolation because I ride the subway and it's loud as heck. These do a great job of blocking out that noise. I love the bass (I listen to pop, indie pop, electronic), I am totally satisfied with these as headphones. There seems to be a bit of an echo when using the mic for talking on the phone. But I can put up with that.
QC15s have complex circuitry that creates a reciprocal sound to drown outside noise (active noise reduction). I initially was sure that active was better than passive, but it's not simply so. I've tried a few active noise reduction headphones and they seem to give me some sort of ringing sound and some headaches even. Plus, active noise reduction technology requires power --- batteries in the case of the QC15s.
This headset works great with the iphone 4. Excellent sound and base quality. It receives sounds better than using the iphone by itself. It cancels out background noise very well. The ear buds seals out external sounds very well to by form fitting to your ear canal. The soft rubber-like plastic earbuds are very comfortable to wear.The headset comes with a little black storage pouch which magnetically seals. The length of the wire is generous.
I bought these earphones to use with my new iPod Shuffle with the VoiceOver feature so that I can listen my audio books. I am very pleased with them. They are easy to insert, seal well to eliminate external noise, and are comfortable to wear. The controller in the cord is easier to use than the one that is part of the standard earphones from Apple that come with the iPod. I'm not an audiophile but I'm very pleased with the quality of the sound they produce.
I bought these after reading a Tech Blogger's review. The sound quality is fantastic and they eliminate almost all other surrounding noise. I was looking for  noise canceling ear buds for use when flying and the noise-isolating feature combined with the convenience of carrying them in your pocket can't be beat.
I previously owned the V-Moda noise canceling headphones and decided I would try a new set of headphones that worked with the new iPhone 3GS. That was a mistake. The sounds is tinny and poor quality. The cable used is thin and brittle and the headphones don't block out background noise. I walk to and from the train to work and these would freeze up in a second unless inside my coat.
Typically, I used these headphones on the subway and they do an excellent job canceling all the background noise, however sometimes too well. While listening to the amazing sound quality it is easy to get too absorbed and miss public service announcements.Overall experience: 9/10The thin wire is really the only thing that I can complain about, other than that these headphones have been nothing short of extraordinary. I would highly recommend these to anybody looking to buy new headphones.
As I become a mainstream smartphone owner, I have been on a quest to find great headphones/mic to listen to music while on the go. I stumbled upon several Web reviews of the Klipsch Image S4i headset and imagined myself in my own world with no external distractions. Once these headphones/mic arrived at my door, I opened the package and it was very well packaged.
So here's what I wanted in a pair of headphones:Quality soundNoise Cancelling (Active or via In-Ear)Inline Volume control and Mic (I have an iPhone 4s)ComfortThey need to stay on/in with heavy sweatThe S4i is the only set of headphones I've gotten with a double flanged earpiece. What this means is that there instead of just one ovular rubber earbud to put on top of the headphone, there is a smaller rubber nub on top of the standard ovular piece.
To use during activities and on the go. The sound quality is good, not superb. These are not the headphones you use when you want to relax and listen to every last detail in your music and have it reproduced perfectly. These are the headphones you use while jogging, walking, riding in a car or plane, using lawn mowers; basically any active pursuit where decent sound quality, ease of use, comfort and noise isolation are important.
Answer: Yes