The sound [ɪ] is said to be more open than [i] and so is [e]. I have no difficulty in distinguishing between [i] and [e], or between [i] and [I]; however, I can hardly distinguish between [ɪ] and [e] when both appear as short vowels, such as represented by the letter I in ich and letter E in Mechanik. To me, they sound too alike in words. Could anyone help with this?
As you correctly say, both [ɪ] and [e] are more open than [i]. However, [e] is even more open (so the order, starting from the least open, is [i] – [ɪ] – [e]), and there is another difference: While [i] and [e] are both front vowels, [ɪ] is produced a bit further back (“near-front”). You can best compare the different positions of all vowels on a vowel chart.
Native German speakers will usually be able to distinguish between [ɪ] and [e] as the difference is in principle phonemic, although the two sounds rarely appear in opposition (mostly due to short [e] being quite rare by itself). If you can’t distinguish them but want to be able to, there is only one way for you: You need to train to hear the difference.
[e] appearing as a short (!) vowel is a very rare case. In standard measures, one would consider the unrounded front vowels of German to be [i:] and [ɪ], [e:] and [ɛ], [ɛ:] (and [ɛ]) and technically also [a:] and [a]; always grouped into pairs of the long and short vowels. These are represented by the letters i, e, ä and a and their variants, respectively. (Note that the distinction between long e and long ä, i.e. [e:] and [ɛ:] is gradually losing its phonemic status; the two are slowly being used interchangeably even though minimal pairs such as Ehre/Ähre exist.)
It is of strong phonemic importance to distinguish [i:]/[ɪ] and [e:]/[ɛ], i.e. the two inside each pare: bitte/biete and Beet/Bett serve as minimal pairs. You should also be able to distinguish between [ɪ]/[ɛ] and [i:]/[e:]; that is also a rather important distinction (bette/bitte and biete/bete). But those for corners of a rectangle are rather far apart, and vowel length helps in the [i:]/[ɪ] and [ɪ]/[e:] cases.
Short [e] only appears in unstressed, unreduced syllables, meaning that there is another (stressed) syllable that you can use to recognise words. Take the following cases (stress marked with an acute accent):
Mechánik. *Michanik does not exist and only in rare cases could I imagine a sentence where ambiguity to mích (although that is stressed) is possible.
lebéndig. Again, the same thing. *Libéndig does not exist. I can actually think of a possible way to have those sounds follow each other across word boundaries, but it is too extreme, so I won’t repeat it.
Much more commonly, unstressed (short) e is reduced to the shwa [ə] as is almost always the case with the prefix ge-.
So all things considered, distinguishing between short [e] and short [ɪ] is not much of an issue.
And finally, note that Mechanik does not have to be pronounced with [e]; I (being from the South) say /mɛ'xanɪk/.
I don't know what your native language is. But since you asked in English, I give you some English examples (and of course German examples):
This is the "near-close near-front unrounded vowel", or "near-high near-front unrounded vowel". You find it in this Englisch words:
- bit [bɪt]
- ink [ɪŋk]
It is in this German words:
- bitte [ˈbɪtə]
- Mitte [ˈmɪtɘ]
"close front unrounded vowel", or "high front unrounded vowel"
- beat [biːt]
- happy ['hæpi]
- Mine [ˈmiːnɘ]
- Idiot [iˈdi̯oːt]
"close-mid front unrounded vowel", or "high-mid front unrounded vowel"
In English this vowel is very rare. You find it only in the pronunciation of Australian English and in some diphthongs:
- bed [bed] (only australian english)
- hate /heɪt/
- Seele [ˈzeːlə]
- beten [ˈbeːtən]
To a German native speaker, [ɪ] and [i] sound very similar, like two variations of the same sound. Also [e] and [ɛ] sound in German ears like two Versions of the same sound. But between [ɪ/i] and [e/ɛ] we hear a big difference. They can't be mixed up in German language.
And so I give you also an description of [ɛ]:
This is the "open-mid front unrounded vowel", or "low-mid front unrounded vowel"
- let [lɛt]
- men [mɛn]
- nett [nɛt]
- Hälfte [ˈhɛlftʰə]
If you have problems with [e], try to speak it as [ɛ]. [e] is half way between [i] and [ɛ].
German [eː] and [ɪ] are very similar to each other in vowel quality. They mainly differ in vowel quantity. Consequently, when [eː] is shortened to [e] in an unstressed syllable, its pronunciation is virtually identical to [ɪ]. As chirlu has explained, this does not pose any problems since it is in stressed syllables where the two vowels are distinct. They seldom occur in unstressed syllables, and I do not believe there are any minimal pairs. Furthermore, as Jan has said, unstressed [eː] may be opened to [ɛ].
The similarity of German [eː] and [ɪ] can be demonstrated by taking recordings of words with [eː] and [ɪ] and artificially lengthening or shortening them (e.g. with Praat).