Can the number and position of non-primary stresses vary depending on the sentence it appears in?
E.g. assuming the word catastrophe, in RP, has a stress on the second syllable
/kəˈtastrəfi/
Can we sometimes stress the 2nd and 3rd, sometimes the 2nd and 4th, and sometimes just the 2nd? Depending on the sentence it appears in.
Yes; this is unsurprisingly called secondary stress.
From Teflpedia:
Secondary stress
Long words may have an extra stress, the second most stressed syllable in the word.
The secondary stress is marked with a small lowered vertical line preceding the stressed syllable: information /ˌɪnfərˈmeɪʃən/, understand /ˌʌndərˈstænd/, represent /ˌreprɪˈzent/.
Words with secondary stress are pronounced as if they were two different words, and one of them has the primary stress: infor-mation, under-stand, repre-sent. If a word has two secondary stresses it is pronounced as three small words: onomatopoeia /ˌɒnəˌmætəˈpiːə/ ono-mato-poeia; heterosexuality /ˌhetərəˌsekʃuːˈælətɪ/ hetero-sexu-ality.
Does the sentence change the position and number of stresses in a word?
Stress is primarily a function of the word. Specifically, the meaning of the word. The sentence simply helps us decode which meaning the word represents.
There are many two-syllable words in English whose meaning and class change with a change in stress. The word present, for example is a two-syllable word. If we stress the first syllable, it is a noun (gift) or an adjective (opposite of absent). But if we stress the second syllable, it becomes a verb (to offer). More examples: the words export, import, contract and object can all be nouns or verbs depending on whether the stress is on the first or second syllable.
Stress can also be a function of who is speaking.
For a few words, native English speakers don't always "agree" on where to put the stress. For example, some people say teleVIsion and others say TELevision. Another example is: CONtroversy and conTROversy.
Context can make a difference. Such as when you're stressing every syllable for someone who's having trouble hearing you.
Can we sometimes stress the 2nd and 3rd, sometimes the 2nd and 4th, and sometimes just the 2nd?
Depends what you mean by and. At the same time in the same word? No.
One word has only one stress. (One word cannot have two stresses. If you hear two stresses, you hear two words. Two stresses cannot be one word. It is true that there can be a "secondary" stress in some words. But a secondary stress is much smaller than the main [primary] stress, and is only used in long words.)
However, there is certainly no rule that says stress must always be on the 1st syllable.
And indeed, you can put the stress anywhere, just to be silly.
There are many two-syllable words stressed on the first syllable for a noun usage, or on the second syllable for the verb sense...
address noun – the location of a building
address verb – to write down an address OR to speak to a group of people
compound noun – something made of two or more parts
compound verb – to combine or add
contest noun – a game or event of competition
contest verb – to challenge or dispute
contract noun – a written agreement
contract verb – to make smaller in size
etc., etc.
I got that list from this Wordpress blog. I can think of one case where the shift is from noun (arithmetic) to adjective (arithmetic), and there's also unionized (labour relations; organised into a union) and unionized (chemistry; not ionised). Offhand though, I can't think of any word where the meaning changes according to the number of stressed syllables.
As @Peter points out below, there are cases such as Rainier (the mountain) with two syllables, where rainier (more rainy) has three syllables. But those are really two different words with different origins, rather that the same word with different meanings according to enunciation.
But I get the impression OP is actually asking if he can "creatively" vary stress patterns in order to effect a change in meaning. To a first approximation I'd have to say No, you can't do that!
Dictionary pronunciation guides excepted, we don't normally indicate the stress orthographically, so you'd need to be in a spoken medium anyway - and unless your audience were primed to expect "meaningfully non-standard delivery" (a poetry reading from a respected writer, perhaps), they'd probably just assume you weren't a very competent speaker.
