In my question about German vowels (asked in German language) I gave examples for all the 30 different vowels in Germans words that I am aware of. Note, that long and short vowels of the same quality are counted as distinct vowels (because for example the pair »Stahl« - »Stall« can be distinguished only by the length of the vowel), and I also counted stressed and unstressed vowels as two different vowels because stress is the only difference between the two version of »umgehen« in »Er versucht die Sperre zu umgehen« and »Ich kann mit dieser Schuld nicht umgehen.«
Two of these 30 vowels are important for your question, because they are different than the 28 other vowels:
- [ə] last sound in the word »Blume« ("flower")
- [ɐ] last sound in the word »Bruder« ("brother")
Next thing you should know:
When talking about stress of syllables there are three different types of syllables in German words:
- stressed syllables (example: 2nd syllable of »entstehen«)
- unstressed syllables (example: 1st syllable of »entstehen«)
- reduction syllables (example: 3rd syllable of »entstehen«)
Reduction syllables are even less stressed than unstressed syllables, and they only can appear at the end of a word. (Well, in compound words they also can appear in the middle of the compound word, but even there, only at the end of an "atomic" word like the syllable »er« in »Jedermann«.)
A German reduction syllable always contains the letter »e« in its written form, but when you pronounce it, only the vowels [ə] or [ɐ] can appear. Never ever can a German reduction syllable have another spoken vowel. They just can have no vowel at all.
- Syllables that are spoken with [ə] (German name: Schwa, English name: schwa)
-e: jede [ˈjeːdə]
-em: jedem [ˈjeːdəm]
-es: jedes [ˈjeːdəs]
-est: zumindest [t͡suˈmɪndəst]
- Syllables that are spoken with [ɐ] (German name: »Tiefschwa« or Fast offener Zentralvokal, English name: near-open central vowel)
-er: jeder [ˈjeːdɐ]
-ern: fordern [ˈfɔʁdɐn]
-ert: hundert [ˈhʊndɐt]
-erst: äußerst [ˈɔɪ̯sɐst]
- Syllables that are spoken without any vowel but with a vocalized sonor consonant
-en: jeden [ˈjeːdn̩] (vocalized N instead of a vowel)
-el: Regel [ˈʁeːɡl̩] (vocalized L instead of a vowel)
-eln: kitzeln [ˈkɪt͡sl̩n] (vocalized L instead of a vowel)
-elt: kitzelt [ˈkɪt͡sl̩t] (vocalized L instead of a vowel)
-elst: kitzelst [ˈkɪt͡sl̩st] (vocalized L instead of a vowel)
Neither [ə] nor [ɐ] can appear in a "normal" i.e. non-reduction syllable, and as the pair »jede - jeder« ([ˈjeːdə] - [ˈjeːdɐ]) demonstrates, they also must not be mixed up.
When a German word in it's written form ends in a syllable that does not contain the letter »e«, then this word can not be pronounced with [ə] or [ɐ].
The pair Joschka - Joschker is not a good example, because the word »Joschker« doesn't exist, so there is no defined pronunciation for it. But I have another pair for you:
- Anka (female first name from Bulgarian and Serbian language)
Pronunciation: [ˈaŋka] (first and second vowel differ only in the amount of stress, but are of the same quality)
- Anker (English; anchor, keeper)
Pronunciation: [ˈaŋkɐ] (first and second syllable are two differnt sounds)
another pair (although the first syllable has vowels of different lengths):
- meta (bound lexeme like in Metaphysik) (same word as in English)
Pronunciation: [ˈmeta]
- Meter (physical unit, same as in English)
Pronunciation: [ˈmeːtɐ]
What is the difference between [a] and [ɐ]?