On the ear
The ear-clips are models that are placed between ear-buds and the smaller on-ear earpad type of headphones and are clipped behind the ear via a plastic or metal clip and have an earpad-style driver being pressed against the ear. Not everyone finds them comfortable and the comfort is also very dependent on the brand/type.
The small earpad type headphones (supra-aural) that come with some portable equipment, in airplanes, hospitals 
and are quite cheap in general. They have foam ear-pieces and rest on the ears connected by a thin, metal or plastic, headband. More luxurious versions exist and good sounding versions exist that can be highly recommended in the price point below E 50.- such as the Koss KSC75 (ear-clip type) which has similar drivers to the Koss PortaPro and SportaPro. The SportaPro does have the same drivers and is cheaper but a totally different headband design which makes it sound way less. The Sporta-Pro is not recommended. The Koss PortaPro and Sennheiser PX100 (as well as the PX100-II which is slightly better than the older PX100) are highly recommended as portable headphones when you want to be aware of your surroundings.
When looking for Koss PortaPro headphones beware there are MANY fakes out there that do not remotely sound anything like the original and are very bassy and lack highs. How to distinguish them can be found HERE.
Also The Jays V-Jays have some good sonic qualities but are more expensive and the square foam pads aren’t the most comfortable ones out there. In the ear-clip designs the Yuin G1A and Yuin G2A are good but pricier alternatives to the Koss KSC35 / KSC75.
Other headphones that you could consider are the AKG K450 and the Sennheiser PX 200 II which differs considerably from the older Sennheiser PX200 which doesn’t sound nearly as good. These last 2 headphones are not as ‘faithfull’ to the sound as the ones mentioned earlier but do have some nice qualities about them that might be appealing to some.
There is also a bigger version with foam ear-pads. Examples are a lot of Sennheiser headphones and Grado headphones. The most famous (legendary ?) Sennheiser headphone with big foam pads is the HD414.
Another very similar headphone is the on-ear with (p)leather or velours earpads and provide a good (or at least better) seal. Some of these clamp rather hard to create a good seal and may become uncomfortable very quickly. The harder clamping ones are not recommended for people wearing
glasses as the ears are pushed against the head with the ear-rests of the glasses between them.. quite painful. Well known examples of this type of headphones are the Sennheiser HD25 (in all it’s editions) and the Beyedynamic DT1350 which both are pricey. The headphones that exert less pressure on the ears (mostly foam pad) do not exhibit this. A cheap headphone in this type that sounds acceptable is the Beyerdynamic DT235.
Noise Cancelling headphones have an amplifier built in it and 1 or 2 small microphones in the earpiece. These microphones are used to ‘cancel’ the sounds coming from the outside or at least lower certain sounds to a great extend. They need batteries to operate and cannot cancel all types of outside noise but are great on airplanes and busses in filtering out humming or constant noises. A headset is another variation and can be earbud, IEM, supra- or circum-aural type and is basically a normal headphone with a microphone attached. Used by gamers and on the go connected to a mobile phone/smartphone.
Open, closed or semi closed (or semi open) headphone types exist and it is important to decide which one you want/need. Open headphones leak sound to the outside world and let sounds from the outside in and certainly the cheaper versions could sound better to most. Semi-closed headphones leak less sounds to the outside world and let in some some as well but noticeably less than fully open ones. Closed (sealed) headphones are literally closed and they leak far less if any sound to the outside world and also let in little to almost no sound from the outside world. Not every type does this equally well (mostly caused by the pads (cushions)) and if you want maximum isolation it is wise to look around. Cheaper closed headphones can exhibit a ‘cuppy’ sound. The better ones can sound equally good as it’s open cousins. Noise cancelling (NC) headphones can also provide good isolation from outside noises only to be surpassed by IEM’s. IEM’s can provide even better isolation and CIEM’s and are the best choice when seeking total isolation.
Sealing issues due to ear-shape
Some people trying out / owning headphones may find their evaluation of their headphone(s) differs considerably from those of other users.
Before blaming it on the headphone(s) find out if you aren’t plagued by fit/seal issues.
The shape of your head, amount / type of hair and ear-shape may be causing a bad seal in combination with some headphones.
If this is the case TEST if you are getting a good SEAL with your headphone(s).
Especially when there is less bass than ‘expected’ or the sound is nasal or otherwise ‘coloured’ in a way that isn’t usually described.
To test for seal simply press the earcups more firmly on your ears. When the sound changes dramatically (most obvious in the bass) then experiment with other pads and or clamping force to address that issue, or find another headphone that doesn’t have sealing issues
DIY-Audio-Heaven 