Harry F B:
Yes, it felt like I was more concentrated at the time, but I was still aware of sounds in my environment, so I'm also not sure if calling the state a trance is accurate as that term suggests to me that I would have been unaware of my surroundings etc...
Your understanding of the trance experience is somewhat faulty. I took a couple of courses in self-hypnosis when I was younger, so I'm speaking from experience.
A person in trance
can be aware of their surroundings. Consciousness is
not lost to one in trance. One of the distinguishing characteristics about trance states is the person's vulnerability to suggestion. This is how stage hypnotists work, by changing mental thought or perception through suggestion. Also, one in trance will recall (after the experience; although they can be aware of this during the experience, too, if they are paying attention) the nature of the mind as having been dull and overly relaxed, without the gatekeeper of
sati on duty to filter any incoming content for its veracity. In other words, the mind becomes susceptible to accepting as true any suggestion that is made to it. Even nonsensical, irrational suggestions (even though not every subject of hypnosis
accepts such suggestions).
Harry F B:
but yet some of the descriptions I've read do seem to suggest that this does happen when a person has entered certain jhana states, that they become completely unaware of their senses and surroundings etc (which could be described as trance-like)...?
The problem with reading about subtle states like
dhyana is that unless the reader knows and has confidence in the source of the information, they may be accepting faulty information as being true. By faulty information, I mean, it may be partially untrue or totally untrue; either way, the person accepting such falsehoods has been compromised in their understanding of the truth, and therefore are more likely to be mislead by what they have accepted as being true.
It sounds like you may have been reading information coming from someone who espouses similar ideas about
dhyana as does Ajahn Brahmavamso, the Englishman Peter Betts who traveled to Thailand in the 1970s and became a student/disciple of the famous Thai Forest meditation master Ajahn Chah. Ajahn Brahm puts out the idea that true "jhana" is only attained with the diminishing and cessation of the senses. But this can be a misleading and ultimately harmful idea to accept. Also, it is
not what his teacher Ajahn Chah espoused!
While it is true that one can attain to a state in
dhyana that is without any sense awareness, such states are
not the only indicator of achieving
dhyana.
Dhyana can be achieved with full awareness of hearing, seeing, smell, taste, and touch. It is the strength and level of one's
sati that maintains one's awareness of these qualities, rather than becoming totally absorbed by the
dhyana experience. In addition, insight could not take place if the mind were totally shut down, hence self-realization would be impossible while in such a state.
Ideally,
dhyana is used to help the meditator to reach states of
samadhi (what some term as
appana samadhi or states of "fixed concentration"). From this platform of "fixed concentration" the mind is totally at ease, bright, malleable, established, cleansed of impurities, workable, and having gained to imperturbability. It is therefore in the perfect condition to perform insight meditation on the Dhamma in order to realize the truths that Gotama taught. Seeing and recognizing these truths from the perspective of one's own direct experience (having gained confidence and assurance in what one is discerning) is what the process of self-realization is all about. Nothing more, nor nothing less.