Observing eight precepts in regular life I've seen some people do this. But how practical is this with the modern lifestyle? As an example the place where I sit in the office is a bit too comfortable. Sometimes there's music in public transport.  If that person shares a place with others or visits other people, they may have to change their lifestyles as well. e.g: eating before noon.

How can one deal with such situations without being a nuisance to others, if someone decides to observe them in day-to-day life?
Simply being in the presence of music or entertainment or sitting in a comfortable chair doesn't break the 8 precepts. Here are the relavent descriptions from the Uposatha Sutta in which the Buddha describes the 8 precepts:


  All of you have given up singing and dancing, the playing of musical
  instruments and the watching of entertainments, which are stumbling
  blocks to that which is wholesome. You do not bedeck yourselves with
  ornaments, flowers or perfume. For all of this day and night, in this
  manner, you will be known as having followed the arahants, and the
  Uposatha will have been observed by you. This is the seventh factor of
  the Uposatha.
  
  ...
  
  All of you have given up lying on large or high beds. You are content
  with low beds or beds made of grass. For all of this day and night, in
  this manner, you will be known as having followed the arahants, and
  the Uposatha will have been observed by you. This is the eighth factor
  of the Uposatha.
  
  http://www.accesstoinsight.org/tipitaka/an/an08/an08.041.vaka.html


With entertainment it is talking about intentionally seeking out or producing entertainment, not about overhearing or seeing someone else doing it, and the giving up of high beds I think is specifically refering to the use of such beds to sleep. I don't think sitting in a chair counts.

Furthermore whenever we interpret the precepts as laypeople (i.e., not interpreting the rules of Vinaya) we have to focus on the underlying principle and purpose of the precepts to decide between different understandings. The purpose of the eight precepts is to live with the renunciation of sensuality and luxury. As a layperson I think it makes sense to say that as long as you are not actively seeking these things out but merely coming across them, you are still acting in accordance with renunciation.