The second aspect of pronunciation that can help with listening, speaking, and language acquisition in general is rhythm. ‘Rhythm’ is the pattern of a language, including its stresses.
When discussing the rhythm of language, the terminology can be intimidating. Isochrony is the technical term for language that has a very clear pattern. Some linguists argue that every language has a pattern, and this is probably true. However, it is more important in some languages than it is in others. In English, isochrony is crucial to interpreting the meaning.
English is a stress-timed language, which is something that helps to explain the schwa. The schwa always occurs on an un-stressed syllable, which helps to create the small and empty sound that it needs. It also explains why so many words use the schwa: without it, it would take a very long time to say anything – there simply isn’t enough time in a stress-timed language to form many vowels.
The easiest way to visualise the pattern of a stress-timed language is by WRI-ting the LANG-uage like THIS. The STRON-ger SYLL-a-bles are STRESSED.
As you can see, it is not as easy as simply STRESS-sing EV-ery OTH-er SYLL-a-ble. Nor is it entirely a case of learning the correct stress pattern for every word: the stress depends upon many things, such as the position of a word in the sentence, and also the intended meaning. However, there are some fairly straightforward ways to practice, and the best place to start is by learning it exactly the same way that English children do: by using what the English call nursery rhymes.
Most nursery rhymes are funny, curious little poems. They have existed in English for hundreds of years, and it is thought that in the past they were the equivalent of pop songs. Indeed, because they were originally meant for grown-ups, some of them are quite dark. For instance, Ring-a-Ring-a-Roses is about the bubonic plague, whilst Humpty Dumpty is about a battle. You can find a good list of nursery rhymes here.
It is then a case of listening to audio versions until you get the hang of it. There is a You Tube series available. Although it is American English in terms of its pronunciation, it is nevertheless a good place to start in order to get the gist.
By training the ear to hear the correct rhythm of English, it becomes much easier to hear the schwa, and therefore to identify different tenses. It is particularly useful for learning to hear the present, past, and future perfect tenses.